U.S. patent application number 12/177269 was filed with the patent office on 2008-11-13 for methods and systems for forming concentrated consumable extracts.
This patent application is currently assigned to XCafe LLC. Invention is credited to Paul A. Kalenian.
Application Number | 20080280023 12/177269 |
Document ID | / |
Family ID | 22583659 |
Filed Date | 2008-11-13 |
United States Patent
Application |
20080280023 |
Kind Code |
A1 |
Kalenian; Paul A. |
November 13, 2008 |
METHODS AND SYSTEMS FOR FORMING CONCENTRATED CONSUMABLE
EXTRACTS
Abstract
Typical known methods for producing large quantities of
concentrated extracts from solid raw materials such as ground,
roasted coffee are not ideally suited to producing high quality
coffee extracts that are rich in flavor and fragrance, and which
maintain the varietal characteristics of the roasted coffee from
which they are produced. The current invention provides filtration
methods e.g. reverse osmosis or nanofiltration for producing such
high quality concentrated extracts from more dilute extracts via
solvent removal. The invention provides methods that have
sufficient flexibility and scalability to be used for a wide
variety of applications, including for producing industrial--scale
quantities of extracts for the food and beverage industry. The
invention provides methods and apparatus that can produce highly
concentrated, "gourmet quality" extracts for use as flavoring
agents, beverage concentrates, and fragrances. The
solvent--reduced, concentrated extracts produced according to the
inventive solvent removal methods can be advantageously used for
applications where high quality coffee extracts, with a high
concentration of soluble coffee solids, for example of at least 6
wt. %-40 wt. %, and a high level of retention of varietal flavor
and fragrance characteristics are desired.
Inventors: |
Kalenian; Paul A.;
(PrInceton, MA) |
Correspondence
Address: |
WOLF GREENFIELD & SACKS, P.C.
600 ATLANTIC AVENUE
BOSTON
MA
02210-2206
US
|
Assignee: |
XCafe LLC
Princeton
MA
|
Family ID: |
22583659 |
Appl. No.: |
12/177269 |
Filed: |
July 22, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10111791 |
Oct 16, 2002 |
7419692 |
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PCT/US00/29651 |
Oct 27, 2000 |
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12177269 |
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60161981 |
Oct 28, 1999 |
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Current U.S.
Class: |
426/655 |
Current CPC
Class: |
A23F 5/28 20130101; A23F
5/262 20130101 |
Class at
Publication: |
426/655 |
International
Class: |
A23F 5/24 20060101
A23F005/24 |
Claims
1-24. (canceled)
25. An aqueous coffee extract obtained by extraction of a quantity
of roasted coffee, said quantity including at least one chosen
variety of roasted coffee, said extract having at least about 15%
wt. dissolved coffee solids, and retaining an effective amount of
the varietal flavor and fragrance components characterizing said at
least one chosen variety of roasted coffee from other varieties of
roasted coffee.
26. The aqueous coffee extract as recited in claim 25, wherein the
extract contains at least about 20% wt. dissolved coffee
solids.
27. The aqueous coffee extract as recited in claim 26, wherein the
extract contains at least about 25% wt. dissolved coffee
solids.
28. The aqueous coffee extract as recited in claim 27, wherein the
extract contains at least about 30% wt. dissolved coffee
solids.
29. The aqueous coffee extract as recited in claim 28, wherein the
extract contains at least about 40% wt. dissolved coffee
solids.
30. A method for producing a blended coffee extract, the method
comprising: a. extracting a quantity of roasted coffee with a
quantity of aqueous solvent to form a first-pass coffee extract
having a concentration of dissolved coffee solids therein of a
first value; b. extracting the same quantity of roasted coffee
previously extracted in step (a) with an additional quantity of
aqueous solvent to form a second-pass coffee extract having a
concentration of dissolved coffee solids therein of a second value
less than first value; c. increasing the concentration of dissolved
coffee solids in the second-pass coffee extract by removing a
quantity of aqueous solvent therefrom; and d. mixing a quantity of
the first-pass extract with a quantity of the second-pass extract
concentrated in step (c) to form a blended extract.
31. The method as recited in claim 30, wherein in step (c) the
concentration of dissolved coffee solids in the second-pass coffee
extract is increased by removing by filtration a quantity of
aqueous solvent therefrom.
32. The method as recited in claim 30, wherein in step (d) the
quantity of the first-pass extract is greater than the quantity of
the second-pass concentrated in step (c).
33. The method as recited in claim 30, wherein in step (d) the
quantity of the first-pass extract is less than the quantity of the
second-pass concentrated in step (c).
34. The method as recited in claim 30, wherein in step (d) the
quantity of the first-pass extract and the quantity of the
second-pass concentrated in step (c) are essentially equal.
35. The method as recited in claim 30, wherein in step (c) the
concentration of dissolved coffee solids in the second-pass extract
is increased to about said first value.
36. The method as recited in claim 35, wherein in step (d) the
quantity of the first-pass extract and the quantity of the
second-pass concentrated in step (c) are essentially equal.
37. A blended coffee extract produced according to the method
recited in claim 30.
38. The method as recited in claim 30, wherein the blended extract
has a concentration of dissolved coffee solids of at least about 6%
wt.
39. A blended coffee extract produced according to the method
recited in claim 38.
40. The method as recited in claim 38, further comprising after
step (d): e. diluting the blended extract with aqueous solvent so
that the concentration of dissolved coffee solids is between about
1% wt. and about 4% wt.
41. (canceled)
Description
RELATED APPLICATIONS
[0001] This application is a national stage filing under 35 U.S.C.
.sctn.371 of International Application No. PCT/US00/29651 filed 27
Oct. 2000, which was published under PCT Article 21(2) in English.
This International application claims the benefit under 35 U.S.C.
.sctn. 119(e) of U.S. Provisional Application Ser. No. 60/161,981,
filed Oct. 28, 1999.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and systems for
producing a consumable aqueous extract from a solid raw material,
and, more specifically, to methods and systems for concentrating
such consumable extracts through the use of filtration. Specific
embodiments of the invention involve methods for forming
concentrated aqueous extracts of roasted coffee useful in food,
fragrance, and beverage products.
BACKGROUND OF THE INVENTION
[0003] A variety of solid raw materials are commonly extracted with
aqueous solvents, such as hot water, to form consumable aqueous
extracts for use in foods, fragrances, or beverages. Common
materials include roasted ground coffee, tea, and cocoa just to
name a few. Typical and representative of currently employed
methods and systems for performing such extractions are those used
for brewing and extracting roasted coffee. Generally the prior art
systems fall into two broad categories: small-scale home or
commercial brewing equipment for producing beverages; and
large-scale industrial extractors for producing concentrated
extracts for use as flavorings or as raw materials for the
production of instant coffee products. When used for the production
of instant coffee products, the aqueous solvent is typically
removed from the dissolved coffee solids by processes such as
freeze drying or spray drying.
[0004] Typical prior art large-scale coffee extractors and
associated extraction methods, especially when used to produce
coffee extracts for the subsequent production of instant coffee,
are designed to exhaustively extract a given quantity of ground
roasted coffee and hydrolyze the cellulose of the roasted coffee.
This is done for economic reasons: the more soluble coffee solids
extracted from a given quantity of roasted coffee raw material, the
greater the quantity of final instant coffee product derived upon
removal of the water by drying. To this end, typical prior art
large-scale coffee extractors are designed for the exhaustive
extraction and hydrolysis of typically low-grade ground coffee and
not for production of a high quality, flavorful, fragrant extract
or for the production of various grades of extract from a given
quantity of ground, roasted coffee. Many typical prior art
extractor systems of this type employ one or more columns having
fixed beds of ground roasted coffee. Representative of such a
system is the one described in U.S. Pat. No. 3,830,940 to Sivetz.
While such systems and methods are useful for exhaustive extraction
with hydrolysis, they are not ideally suited for producing high
quality coffee extracts with desirable sweetness and flavor
characteristics or for production of various grades of extracts
from a given choice of ground, roasted coffee. The relatively long
extraction times (for example greater than 1 hour), high water
temperatures, and levels of dilution used in certain prior art
extraction processes can result in extracts having poor flavor or
fragrance characteristics, which are often passed on to the dried
instant coffee products produced from such extracts. Furthermore,
the process of de-watering the extracts by typical prior art
methods, such as spray drying or freeze drying, in forming the
instant coffee products can result in the loss or degradation of
desirable varietal flavor and fragrance components of the ground,
roasted coffee. Many of the concentrated coffee extracts commonly
employed as flavor components in the food industry (e.g. as
flavorings for coffee ice cream, iced coffee beverages, and coffee
syrups) are produced by reconstituting such poor quality instant
coffee products with water or other materials.
[0005] It is understood that sweeter and more flavorful coffee
extract can be produced near the beginning of an extraction cycle,
when the fresh ground coffee has been in contact for a relatively
short period of time with only a relatively small quantity of
water, than can be produced later in the extraction process after
the coffee has been exposed to additional quantities of water and
more exhaustive extraction. Attempts have been made to improve upon
the quality and flavor of coffee extracts and instant coffee
products produced by large scale extraction processes. One such
method described in U.S. Pat. No. 4,534,985 to Gasau ('985)
discloses an industrial scale continuous extraction process and
apparatus for the extraction of coffee or tea. The apparatus
involves a complex system using a number of extractant beds and
extraction zones, where the beds are movable between zones by
rotation of the apparatus. The process reduces the total time of
the extraction process when compared to more conventional prior art
extraction methods. The '985 patent also discloses the use of
compressed air or an inert gas in a "recovery station" of the
apparatus to maximize recovery of the residual liquid present in
the spent grounds after extraction.
[0006] Various smaller scale brewing/extraction methods for home or
commercial use are known in the prior art for producing beverages
from solid raw materials such as coffee, tea and cocoa. Common
methods include steeping or infusion in a static volume of hot
water (i.e. steeping a tea bag in a cup of hot water), steam-driven
percolation, and extraction via a continuous flow of hot water
under the force of gravity through a bed of solid extractable
material, typically coffee. The latter method described is the one
typically employed in home "drip method" coffee makers. All of
these methods typically produce a relatively dilute
beverage-strength extract (typically, 1 lb of ground, roasted
coffee will yield about 320 oz. of beverage-strength extract). In
addition, because of the continuous addition of water used to drive
the flow of extract through the bed, the beverages produced can
contain flavor and/or fragrance undesirable quantities of certain
bitter components, which may be undesirable for certain
applications. Also, because these prior art methods brew in the
presence of oxygen, the flavor and fragrance of the resulting
extract can be degraded by undesirable oxidation.
[0007] An improvement to most of the above described methods for
applications where it is desired to produce a more concentrated
coffee beverage having a sweeter flavor and fragrance, is the
espresso method of coffee extraction. The espresso method of
extraction typically employs a small-scale home or commercial
brewing apparatus utilizing a less exhaustive extraction method to
produce a relatively sweet, more concentrated beverage. Typically,
a higher ratio of ground coffee to hot water is employed, for
example about 1 lb. of ground roasted coffee may typically yield
about 64-128 oz of coffee beverage. In order to allow sufficient
contact time between water and the ground coffee, the method
typically utilizes a finely ground coffee (e.g. 14 gram weight)
with hot water being forced through the bed of grounds contained in
the brew chamber by additional pressurized hot water. Most typical
currently employed espresso type extraction devices are capable of
producing only relatively small quantities of extract during each
extraction cycle. In addition the quality of the beverage can be
very dependant on the grind and packing of the coffee, which
dictates the back pressure developed by the flowing water during
the extraction, and the extraction time for a given total volume of
beverage. A lack of control over these variables can lead to a poor
or inconsistent quality of extract. Also, since hot water is
typically used to force extract from the bed of ground coffee
during the entire extraction process, a level of extraction that is
undesirable for certain applications may still occur, yielding an
extract which may be too dilute for certain applications, and may
not be ideally suited for use as a food or flavor additive.
[0008] A variety of small-scale espresso style coffee brewers have
been described which attempt to improve upon the performance of
conventional espresso brewers. U.S. Pat. No. 5,127,318 to Selby
('318) and U.S. Pat. No. 5,473,973 to Cortese ('973) both disclose
an apparatus and process for extracting espresso type coffee in
which the pressure within the extraction region is regulated by a
biased valving arrangement on the outlet line downstream of the
coffee bed. The valves are designed to remain closed during the
initial pressurization of the extraction chamber by hot water until
a preset pressure is reached that can overcome the bias of the
regulating valve. When such pressure is reached, the valve opens
for flow and maintains a relatively constant pressure in the
extraction chamber during the remainder of the extraction process
relatively independent of the grind or packing of the coffee. In
the disclosed systems, the pressure constantly rises until a
predetermined pressure is reached, at which point, flow immediately
commences.
[0009] U.S. Pat. No. 5,267,506 to Cai ('506) discloses an apparatus
for automatically brewing espresso coffee and includes one
embodiment where pressurized steam generated by a heating unit is
passed through the coffee grounds to purge liquid so that the
grounds will not drip when the brew chamber is removed.
[0010] U.S. Pat. No. 5,337,652 to Fischer et al. ('652) discloses
an espresso machine and method utilizing a biased pressure relief
valve down stream of the brewing chamber similar to U.S. Pat. No.
5,127,318 ('318) and U.S. Pat. No. 5,473,973 ('973) described
above. The biased valve prevents flow from leaving the discharge
line until the pressure within the chamber rises to a fixed
predetermined level; immediately thereafter, the valve opens and
maintains a relatively constant pressure within the brew chamber
during the remainder of the extraction. The '652 system also
includes an air pump with an outlet line in fluid communication
with the water heating chamber. The air pump is used at the end of
the brewing cycle to pump air through the coffee grounds in order
to dry the coffee and produce a foamy head. The air from the pump
is directed to the brewing chamber from the hot water compartment
via a relatively complex automated valving/switching mechanism on a
flow control manifold located within the water heating chamber. The
air supplied to the brewing chamber in the '652 system passes
through the water heating chamber before entering the brewing
chamber thus adding heat and moisture to the gas. While some of the
above cited systems and methods for producing consumable extracts
from solid raw materials represent, in some cases, useful
contributions to the art of producing consumable extracts, there
exists a need for improved methods and systems for producing
variable quantities, including large volumes, of consumable
extracts, including highly concentrated extracts, from solid raw
materials, the extracts having a desirable combination of
sweetness, flavor, and fragrance characteristics.
SUMMARY OF THE INVENTION
[0011] Accordingly, the present invention, in some embodiments, can
provide improved methods and apparatuses able to controllably
produce highly concentrated or less highly concentrated consumable
extracts having excellent and desirable sweetness, flavor, and
fragrance qualities from solid raw materials. In other embodiments,
methods and apparatuses are provided that utilize filtration
methods, such as reverse osmosis and/or nanofiltration, to remove
excess solvent from consumable extracts to produce more
concentrated extracts with minimal loss of desirable flavor and
fragrance characteristics.
[0012] In one aspect, a method is described for increasing the
concentration of a consumable material in a consumable extract. In
one embodiment, the method comprises supplying the extract to the
retentate side of a filter and passing at least a portion of the
solvent component of the extract through a filtration medium to
form a permeate on the permeate side of the filter while retaining
at least a portion of the consumable material on the retentate side
of the filter, thereby forming a solvent-reduced consumable
extract. This solvent-reduced consumable extract is more
concentrated in the consumable material and is collected from the
retentate side of the filter.
[0013] In another embodiment, a method for producing a blended
coffee extract is disclosed. The method comprises extracting a
quantity of roasted coffee with a quantity of aqueous solvent to
form a first-pass coffee extract having a concentration of
dissolved coffee solids of a first value. The method further
involves extracting the same quantity of roasted coffee previously
extracted in the above step with an additional quantity of aqueous
solvent to form a second-pass coffee extract having a concentration
of dissolved coffee solids therein of a second value that is less
than the first value. The method further comprises increasing the
concentration of dissolved coffee solids in the second-pass coffee
extract by removing a quantity of aqueous solvent from the
second-pass extract. The method further includes mixing a quantity
of the first-pass extract with a quantity of the second-pass
extract, concentrated in the above step, to form a blended
extract.
[0014] In another aspect, an aqueous coffee extract is disclosed.
The extract is obtained by extraction of a quantity of roasted
coffee that includes at least one chosen variety of roasted coffee.
The extract contains at least about 15% wt. dissolved coffee solids
and retains an effective amount of the varietal flavor and
fragrance components characterizing the at least one chosen variety
of roasted coffee from other varieties of roasted coffee.
[0015] Other advantages, novel features, and objects of the
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings, which are schematic and which are not
intended to be drawn to scale. In the Figures, each identical or
similar component that is illustrated in various Figures is
represented by a single numeral. For purposes of clarity, not every
component is labeled in every Figure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic illustration of an apparatus for
forming a consumable extract from a solid raw material according to
one embodiment of the invention;
[0017] FIG. 2 is a schematic illustration of the apparatus shown in
FIG. 1 as viewed from the top;
[0018] FIG. 3 shows a cross-section of the apparatus in FIG. 1 as
viewed from the top showing one embodiment of a filter element
comprising a porous screen;
[0019] FIG. 4 is a cross-section of the apparatus of FIG. 1 viewed
from the side showing the enclosed internal volume and internal
components of the vessel;
[0020] FIG. 5 is a schematic illustration of a portion of a filter
system for concentrating a consumable extract, according to some
embodiments of the invention; and
[0021] FIG. 6 is a schematic process flow diagram of a
filtration-based extract concentration system, according to one
embodiment of the invention
[0022] FIG. 7 is a schematic process flow diagram of a
filtration-based extract concentration system, according to another
embodiment of the invention
[0023] FIG. 8 is a schematic process flow diagram of a
filtration-based extract concentration system, according to another
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] The present invention involves methods for forming
consumable extracts containing a consumable material from a variety
of solid raw materials, which extracts can be of superior quality
with regard to flavor and fragrance compared to similar extracts
produced according to typical prior art extraction methods. Some
embodiments of the invention also involve novel methods for
removing excess solvent from consumable extracts to form a more
concentrated extract, without substantially degrading the flavor
and fragrance characteristics of the extract. The term "consumable
extract" as used herein, refers to a solution containing a
dissolved or suspended consumable material in a consumable solvent.
A "consumable solvent" refers to an essentially non-toxic,
ingestible liquid that has the ability to dissolve or suspend a
non-zero quantity of the consumable material. "Consumable material"
as used herein, refers to an extractable component of a solid raw
material that is extracted by, and can be dissolved or suspended
in, the consumable solvent. A "solid raw material" as used herein,
refers to a solid material including at least one solid component
that is insoluble in the consumable solvent and at least one other
component that is a consumable material. Preferred consumable
solvents for use in the invention are aqueous solvents. An "aqueous
solvent" according to the invention comprises water, and may
additionally include other components that are soluble or miscible
in the water, which components may be useful or desired for
particular applications. When an aqueous solvent is employed in the
invention, the consumable extracts produced will be aqueous
extracts.
[0025] The solid raw materials that may be advantageously employed
according to the invention can include a variety of organic solids
from which consumable materials can be extracted, for example, tea
leaves, cocoa, fruit, vanilla beans, and roasted coffee. While it
should be understood that the methods and apparatus described
herein in accordance with the invention can potentially be used for
any suitable solid raw material, including but not limited to those
listed above, to exemplify the method for the purpose of the
detailed description, specific reference will be made to roasted
coffee.
[0026] Unlike typical prior art methods and apparatus for producing
aqueous extracts from roasted coffee (i.e. coffee extracts), the
current invention enables the production of relatively concentrated
coffee extracts that exhibit a high level of sweetness and flavor
quality and retain the varietal characteristics specific to the
particular variety of coffee being extracted. Unlike typical prior
art methods for producing concentrated coffee extracts, for example
for use in producing instant coffee, the inventive methods, in some
embodiments, avoid exhaustive extraction of the roasted coffee with
high water temperatures that can lead to hydrolysis (typically
above the boiling point of water at atmospheric pressure), which
can lead to loss of fragrance and extraction of an undesirable
quantity of bitter components and acids that can adversely affect
the flavor and fragrance of the extract. In some embodiments, more
than one different grade of extract may be produced from a given
quantity of ground roasted coffee, with each extract produced at a
different level of exhaustion of the coffee. As described in more
detail below, these extracts can be concentrated and combined in a
variety of ways to yield combined extracts having a variety of
flavor/fragrance characteristics.
[0027] Coffee's sweetest flavors are typically produced during the
first part of any brewing (extraction) cycle for typical prior art
methods. Rich flavors, sugars, and aroma are extracted first. Oils,
acids, and more bitter flavor components brew out in the later
phase of brewing when more extensive extraction has occurred. This,
for example, is why some percolated coffee beverage and coffee
extract produced by exhaustive extraction is often bitter in
flavor, has weak aroma, and has oils on the surface.
[0028] For applications where coffee extracts having superior
fragrance and flavor are typically not considered crucial, for
example for production of instant coffee products, exhaustive
extraction with hydrolysis has been utilized in an attempt to
maximize the total yield of consumable material (i.e. soluble
coffee solids) that can be obtained from a given quantity of solid
raw material (i.e. roasted coffee). However, because of harsh
extraction conditions and solvent removal conditions often employed
in these prior art processes, when reconstituted with water or
another solvent to form a coffee beverage or coffee extract for use
as a food, flavoring, or fragrance component, such prior art
products typically do not provide the flavor and/or fragrance
characteristics demanded by consumers who appreciate superior
quality coffee. Specifically, these prior art exhaustive extraction
methods typically produce coffee extracts that do not retain the
desirable varietal flavor and fragrance components that can
distinguish extracts produced from coffee grown in one particular
region or country or blends of two or more such coffees over other,
different varieties. The extracts produced according to the present
invention can provide flavor and fragrance attributes that enable
them to be utilized in "specialty" coffee applications, and for
those embodiments designed for such specialty coffee applications,
retain an effective amount of the varietal flavor and fragrance
components characterizing the particular variety of roasted coffee
from which the extract was produced. The varietal flavor and
fragrance components, advantageously retained in coffee extracts
produced according to these embodiments of the invention, are
relatively volatile extractable chemical compounds, or combinations
of chemical compounds, present in the roasted coffee. Different
coffee varieties (e.g. Costa Rican Tarrazu vs. Sumatran
Mandheling), or defined mixtures or blends of such varieties, will
typically possess different relative amounts of and/or types of
these varietal flavor and fragrance components that distinguishes
the flavors and fragrances of the different brewed coffees. The
presence of these varietal flavor and fragrance components is
conventionally determined by cupping (taste and smell testing) by
those skilled in the art. Unlike typical prior art methods of
producing relatively concentrated coffee extracts, which do not
contain effective amounts of these varietal components, the present
invention can provide relatively concentrated coffee extracts that
do retain effective amounts.
[0029] "Relatively concentrated coffee extract" as used herein,
refers to a coffee extract that is more concentrated than coffee
beverage-strength extract (typically about 1-4% wt. dissolved
coffee solids) and contains at least about 6% wt. dissolved coffee
solids. An "effective amount" as used herein in reference to the
amount of varietal components retained in a coffee extract refers
to a concentration of such components in the extract sufficient to
be detected, in the concentrated extract itself or in a coffee
beverage obtained by diluting the extract to beverage strength with
additional water, by taste and/or smell by one of ordinary skill in
the art of cupping (taste-testing) coffee. "Detected" as used above
refers to the ability of such a taste tester to distinguish, due to
the presence of the varietal components, extracts produced by the
same method but from different varieties of roasted coffee.
Alternatively, the presence of an effective amount of varietal
components can be determined and defined by performing standard
chemical analysis on the coffee extracts. Such analysis can be
performed by a variety of methods apparent to one skilled in the
art, for example, gas chromatography, liquid chromatography, mass
spectrometry, etc. An "effective amount" of varietal components as
measured by such methods can be defined by comparing the analysis
of a beverage-strength extract produced by a typical prior art
beverage brewing method, such as the drip method or espresso
method, both discussed in more detail herein, with a concentrated
extract that has been diluted with additional water to have the
same total dissolved solids as the beverage-strength extract to
which it is being compared. A diluted concentrated extract so
analyzed with an "effective amount" of varietal components, will
contain about the same or greater concentration of such components
as the beverage-strength extract produced by the typical prior art
beverage brewing method.
[0030] In addition, because the inventive methods provide
flexibility to produce coffee extracts having a wide range of
solubles concentration, including highly concentrated extracts,
many of the extracts produced according to the invention can, in
some embodiments, be used directly for applications where highly
concentrated coffee extracts are desirable, without the need for
additional concentration by solvent removal. For example,
concentrated coffee extracts produced according to some embodiments
of the invention can be used for producing coffee syrups, coffee
ice creams, iced coffee beverages, coffee perfume, etc., all of
which can display excellent flavor, sweetness, and/or fragrance and
maintain the varietal characteristics of the coffee from which the
products were produced. For other embodiments where it may be
desirable to even further concentrate the extracts produced by
extraction of the ground, roasted coffee, the invention provides
novel filtration-based methods, for example reverse osmosis
methods, for removing excess solvent (e.g. de-watering) from the
extract, preferably without unduly degrading the flavor and
fragrance qualities of the dilute extract. Such solvent removal
methods can be especially useful for forming concentrated extracts
in embodiments involving exhaustive or relatively high levels of
extraction of the ground, roasted coffee with relatively large
quantities of extraction solvent.
[0031] The current invention also provides methods and apparatus
that are flexible enough to allow for production of a wide variety
of extracts having different concentrations and degrees of
extraction to suit a variety of purposes and applications. The
inventive methods and apparatus are also easily scalable to provide
a means for producing any desired quantity of extract. Small-scale
versions of the apparatus, according to the invention, could be
used for home or retail/commercial use, while larger scale
apparatus, more specifically described herein, may be used for
industrial production of coffee extracts.
[0032] The current methods for forming extracts and for de-watering
extracts, according to the invention, allow the level of
extraction, and concentration of coffee extract to be more
precisely controlled than with typical prior art devices and
methods. For example, typical drip-style coffee brewers, commonly
employed for home and commercial use, typically produce about 2.5
gallons of coffee beverage per 1 lb. of ground roasted coffee,
yielding a typical dissolved solids concentration of about 1-1.5%
wt. Another popular method of producing coffee beverage is the
"espresso method," which typically involves forcing hot water
through finely ground, roasted coffee under pressure (typically
about 120-140 psig depending on the fineness of the grind and the
water flow rate) over a short period of time to create an "espresso
beverage." Such methods typically create about 1 gallon of coffee
beverage from about 1 lb. of coffee and produce a beverage
containing up to about 4% wt. dissolved coffee solids. In general,
the "espresso method" typically produces a sweeter, more
concentrated beverage than the drip method because it utilizes a
greater ratio of coffee to water, while also reducing the level of
extraction of the raw material (ground coffee). Apparatus for
producing coffee beverage according to the espresso method is
typically limited to small scale devices having a maximum capacity
of about 14 grams of dry, ground roasted coffee. In contrast, the
present invention provides, in certain embodiments, methods and
apparatus for producing coffee extracts from large quantities, in
some embodiments 300-1300 lb., of roasted coffee. The invention
also allows for a variety of coffee extracts having a variety of
flavor/fragrance characteristics and/or concentrations to be
produced according to the needs of the user by allowing the user to
easily adjust the ratio of extract produced to roasted coffee
employed according to need. For example, the extracts produced
according to the invention can range from those of drip coffee
strength (1 lb. dry coffee per 2.5 gallons of extract) or less, to
highly concentrated extracts, for example using 2.5 lb., 5 lb, 7
lb., 10 lb., 15 lb., 20 lb., 25 lb., 30 lb., or 40 lb. of dry
coffee or even more, per 1 gallon of extract produced, yielding
concentrations of dissolved coffee solids that can be in excess of
10% wt., 15% wt., 20% wt., 25% wt., 30% wt., or 40% wt. The flavor
and fragrance quality of the extracts produced according to the
invention varies according to the degree of dilution and extraction
during the extraction process, with extracts produced at lower
levels of extraction of the roasted coffee typically having the
greatest sweetness, and extracts produced at higher levels of
extraction and greater solvent dilution, which extracts can
subsequently be concentrated by filtration/reverse osmosis as
described in more detail below, having more bitter and acidic
flavor components. As described in more detail below, for certain
applications, extracts produced at relatively low levels of
extraction can be selectively combined with extracts produced at
higher levels of extraction to produce combined extracts having a
desired level of balance of sweetness and flavor/fragrance
qualities. Such extracts can be selectively formulated to yield a
flavor/fragrance balance for particular applications; for example,
in one preferred embodiment, a quantity of high-sweetness extract
produced at a low level of extraction can be combined with an
extract produced at a higher level of extraction, and subsequently
de-watered to a solubles concentration level similar to that of the
high-sweetness extract, to produce a concentrated extract which
yields a well-balanced, flavorful coffee beverage upon
reconstitution of the extract with sufficient water to yield
beverage strength coffee.
[0033] The basic features of the inventive methods for producing
consumable extracts from solid raw materials will now be explained
in reference to the formation of coffee extracts. Following the
basic description, a more detailed description of each step will be
given with reference to one illustrative embodiment of an
extraction apparatus shown in FIGS. 1-4.
[0034] The inventive extraction methods, in some embodiments, are
similar, in some respects, to the "espresso method" of coffee
extraction previously described. The inventive method utilizes an
extraction vessel, chamber, or enclosure having an enclosed
internal volume sufficient to contain a desired quantity of solid
raw material, for example roasted coffee. A wide variety of
extraction vessel sizes and configurations can potentially be
employed for various applications as apparent to the skilled
artisan. The vessel should be sealable, so that the internal volume
can be pressurized to a desired level without undesirable leakage,
and have at least one inlet line and at least one outlet line for
fluid flow therethrough to enable a continuous flow of solvent
through the solid raw material (e.g. coffee) contained within the
internal volume of the vessel. The vessel should also have means
for filling the internal volume with roasted coffee; for example,
the vessel can comprise two or more separable parts that may be
separated to expose the internal volume for filling, and/or may
have one or more lines through a wall of the vessel and in
communication with the internal volume through which roasted coffee
may be inserted into the internal volume. The inlet and outlet
lines for fluid flow are preferably located on the vessel on
opposite sides of the internal volume containing the coffee so that
essentially all of the fluid flow entering the vessel through the
inlet line and leaving the vessel through the outlet line passes
through essentially the entire quantity of coffee as it flows
through the vessel. A preferred configuration of the vessel has one
or more inlet lines located at or near a top surface of the vessel
and one or more extract outlet lines located at or near a bottom
surface of the vessel, thus allowing, in preferred embodiments, a
flow of aqueous solvent through the coffee to proceed from above
the level of the coffee in the internal volume and through the
quantity of coffee in the internal volume in the direction of
gravity. Such flow through the coffee in the direction of gravity
acts to compress the coffee during flow-through extraction and
improve contact between the solvent and the coffee, thus improving
the extraction process performance as compared to a solvent flow
against the direction of gravity or perpendicular to the direction
of gravity.
[0035] One embodiment of a method for forming a coffee extract
according to the invention involves first at least partially, and
preferably essentially entirely, filling the internal volume of the
vessel with roasted coffee. With the certain lines closed and at
least one valve on a line in fluid communication with the internal
volume of the vessel open, the vessel is at least partially filled
with an aqueous solvent. The aqueous solvent can be filled, in some
embodiments, through inlet line(s) on the top of the vessel, or,
more preferably, at least a portion of the initial filling of the
vessel with aqueous solvent can be performed by flowing the aqueous
solvent into the vessel through one or more lines positioned near
the bottom of the vessel, for example below the filter screen used,
in other steps of the extraction process as extract outlet lines or
washout lines. This latter filling process can help reduce
potential clogging of the filter screen (see FIG. 3 and discussion
below) with fines of the roasted coffee by back-flushing the screen
during initial filling with aqueous solvent.
[0036] Preferably, enough aqueous solvent is added to fill the void
volume of the quantity of roasted coffee in the vessel and
completely cover and wet the roasted coffee. The outlet lines are
preferably closed through means of at least one controllable valve.
A "controllable valve" as used herein refers to a valve that may be
manually or automatically operated, for example by hand turning or
computer control and actuation, as desired by an operator to open,
close, and/or partially open or close the valve at any desired time
and under a variety of desired operating conditions. Such valves
may be gate valves, globe valves, ball valves, needle valves, etc.
as apparent to the skilled artisan and are distinguished from
valves which open and close at one preset condition without
operator control, such as, for example, a biased pressure relief
valve. In preferred embodiments, the temperature of the aqueous
solvent in contact with the coffee is above ambient temperature,
most preferably, it is between 190 and 212 degrees Fahrenheit.
[0037] Preferred embodiments of the extraction method, subsequent
to the filling steps outlined above, next subject the roasted
coffee to a novel "pressure-treat" step, which facilitates thorough
wetting of the coffee and the elimination of air pockets or
channels, as well as penetration of the aqueous solvent into the
coffee particles themselves to increase the efficiency of
extraction. The pressure-treat step is performed by increasing the
static pressure in the vessel containing the coffee and aqueous
solvent to a predetermined and controllable pressure above
atmospheric pressure while maintaining the outlet valves in a
closed configuration so as to prevent any flow of extract from the
vessel. The vessel can be pressurized by addition of additional
pressurized aqueous solvent, or alternatively by addition of a
pressurized gas to the vessel from an external source of
pressurized gas through an inlet line to the vessel. The pressure
is maintained for a desired period of time before flow of extract
is established. The optimal level of pressure for use in this
"pressure-treat" step depends on whether the roasted coffee is in
the form of whole beans or ground, the fineness of the grind (for
ground coffee), the type of coffee, the degree of roasting, etc.,
and should be determined by the operator, using routine
experimentation and/or optimization, for a given set of conditions
to produce an extract with desired characteristics. In general, the
coarser the grind of coffee, the higher the pressure should be to
yield maximum benefit from the pressure-treatment. It has been
found that for many types of ground coffee (e.g. roasted coffee
ground using a Bunn coffee grinder (HVG, Bunn-o-matic, Springfield,
Ill., on a setting of 4.0, or roasted coffee ground to a similar
average coarseness using a roller mill grinder) the pressure during
the pressure-treat step is preferably at least about 40-50 psig, in
some embodiments at least about 100 psig, and, in certain preferred
embodiments, between about 120 and 132 psig. For embodiments where
coarser ground coffee or whole bean coffee is used, the pressure is
preferably higher than this range, for example 150-1000 psig or
more. The pressure is maintained under non-flow conditions for a
predetermined and controllable period of time before the onset of
flow. The time of treatment can vary from several seconds to
several minutes, with a typical static pressure treatment time
being about 10-30 min.
[0038] Upon completion of the static pressure-treat step, an outlet
valve is at least partially opened to establish flow of extract
from the vessel, and, for some embodiments, additional aqueous
solvent is simultaneously fed to the vessel through an inlet line.
The valve on the outlet line can be controlled to maintain a
desired level of pressure within the vessel during the flow-through
extraction. Thus, the ability of the operator to select and control
the pressure in the vessel via control of an outlet valve allows
the pressure during extraction and to be adjusted and controlled
within the vessel independent of the fineness of the grind of
coffee or the inlet solvent and/or gas flow rate. For embodiments
where a very concentrated extract is desired, very little or no
additional aqueous solvent is supplied during flow of the extract
from the vessel. For other embodiments, a measured, desired
quantity of additional aqueous solvent is supplied to yield a
desired level of extraction and final extract concentration.
[0039] After a desired quantity of additional solvent has been
supplied, the flow of solvent is discontinued and extract is
collected through the outlet line, typically until the vessel is
equilibrated with atmospheric pressure. At this point, in preferred
embodiments of the method, residual extract present within the void
volume of the ground coffee is removed and recovered by supplying
the vessel with a flow of fluid that is a gas (at standard
temperature and pressure) through an inlet line to the vessel,
which is in direct fluid communication with the enclosed internal
volume, from a source of compressed gas external to the vessel. The
gas flow to the vessel displaces the extract from the wet coffee,
which extract is collected from the outlet line and added to the
extract collected during the previous step. Purging the wet coffee
with a gas allows the concentrated extract present within the void
volume, defined by interstices between and within the wet coffee
particles, to be recovered instead of wasted as in typical
espresso-type coffee extractors. It also allows for a given volume
of extract to be collected with less dilution and a lower degree of
extraction when compared to prior art methods where all of the
extract collected is forced from the coffee with additional
solvent. The gas used to purge the coffee, in preferred
embodiments, does not act as a solvent and, therefore, does not
further extract or dilute the coffee extract collected. Preferred
gases for use in the invention are relatively inert with respect to
the solvent, extract, and solid raw material. Compressed air may be
used in this context, but particularly preferred gases include
oxygen-free inert gases such as nitrogen, or noble gases such as
argon, helium, etc. "Inert gas" as used herein, refers to gases
that are not reactive with the solid raw material, aqueous solvent,
and aqueous extract and that do not significantly affect the flavor
or fragrance characteristics of the aqueous extract. Preferred
gases, so as not to adversely affect the flavor of the extract, are
also essentially insoluble, only sparingly soluble, or not very
soluble in the aqueous solvent. For example, gases such as carbon
dioxide, which is very soluble in the aqueous solvent and causes
"carbonation" thereof, are generally not preferred for use in the
invention. It is also preferable to supply the gas to the vessel at
ambient or sub-ambient temperature so as to beneficially cool the
solid raw material and prevent release of off-flavors/fragrances
into the extract.
[0040] The steps of the inventive method outlined above may be
modified, or certain steps may be deleted, or additional steps
added, according to the needs and desires of the operator. For
example, in some embodiments of the method, the static
pressure-treat step can be omitted. In such an embodiment, after
filling the internal volume of the vessel with dry roasted coffee,
a continuous flow of aqueous solvent can be established through the
coffee whose dynamic pressure drop is controllable by adjustment of
the controllable outlet valve on the outlet line through which
extract is collected, and/or by controlling the inlet flow rate of
aqueous solvent. Then, after supplying a desired predetermined
volume of aqueous solvent for extraction, the solvent flow is
discontinued and the extract remaining in the wet coffee is purged
with a gas as previously described. In some embodiments where a
particularly concentrated extract is desired, the predetermined
volume of aqueous solvent supplied as described above is
essentially equal to the void volume of the bed of the dry, roasted
coffee contained within the vessel.
[0041] The inventive methods outlined above are also flexible and
can be used to provide a variety of extracts of differing
concentration and degree of extraction from a single quantity of
solid raw material. For example, the same quantity of solid raw
material can be subjected to multiple, repetitive application of
the methods described above to produce a variety of extracts from
the same given quantity of solid raw material, each extract having
a different concentration and flavor/fragrance characteristics
indicative of the degree of extraction, with the extracts produced
by the first-pass extraction procedure being the most concentrated
and having the sweetest flavor/fragrance characteristics, and with
subsequent extracts being progressively weaker and including more
bitter and acidic taste/flavor components. Using such a multi-cycle
method to perform multiple extractions can allow for custom
production of a variety of extracts for a variety of purposes, with
even more extracts being obtainable by selective combinations of
two or more of the above extracts, while at the same time
increasing the utilization and yield from a given batch of raw
material. The modified, multi-cycle method here described can be
analogous, in some embodiments, to the production of various
quality olive oils (e.g. extra virgin, virgin, etc.) from multiple
pressings of the same olives. In the present case, various quality
coffee extracts can be produced from multiple cycles utilizing the
same batch of roasted coffee. In addition, if desired, the extract
produced from one cycle of the extraction can be recycled and used
as the aqueous solvent for a subsequent extraction cycle either
with the same charge of solid raw material or a fresh load of solid
raw material.
[0042] Also, as described in more detail below, the extracts
produced at higher levels of extraction of the roasted coffee,
which are typically more diluted with aqueous solvent, can, in some
embodiments, be advantageously concentrated in coffee solids by
removing a portion of the aqueous solvent from the extract as a
permeate using the inventive filtration methods, so that they have
a solids concentration similar to or exceeding that of the extract
produced by the first-pass extraction. Blended extracts, having
more balanced sweet/bitter flavor/fragrance characteristics, can
then be produced by selective mixing of first-pass extracts with
subsequent extracts that have been concentrated without any
dilution in the overall solids concentration. Alternatively, the
extracts may be mixed together after extraction and prior to
de-watering, and the combined extract then subjected to de-watering
to a desired final coffee solids concentration. Furthermore, the
aqueous solvent removed from the extracts by certain of the
inventive filtration methods, such as reverse osmosis or
nanofiltration, may contain substances (e.g. caffeine) that render
it commercially valuable as a product. The aqueous solvent removed
as permeate from the extracts by certain inventive filtration
methods, such as reverse osmosis, may also have enhanced salvation
power for performing subsequent coffee extractions owing to the
solvent having a lower level of mineral hardness. Such a permeate
can be re-used, in some embodiments, as the aqueous solvent, or a
component thereof, for performing subsequent extraction cycles on a
previously extracted quantity of roasted coffee, or can be used as
the aqueous solvent, or a component thereof, for performing a new,
first-pass extraction on a fresh charge of roasted coffee.
[0043] One embodiment of an industrial-scale extraction apparatus
and system 10 for performing the methods according to the invention
is shown schematically in FIGS. 1-4. It should be noted that some
components that would be apparent to the skilled artisan are not
necessarily shown in the figures, and that the particular
arrangement of components is only illustrative, which components
may be repositioned, or otherwise interconnected, substituted, or
combined as apparent to the skilled artisan. Referring first to
FIG. 1, the apparatus includes a cylindrical pressure vessel 11
having a removable top plate 12 and a removable bottom plate 13.
The apparatus can be disassembled to allow for inspection, clean
out, and/or replacement of internal components. In other
embodiments, especially for small-scale systems, the vessel may be
a single component that does not disassemble. Top plate 12 and
bottom plate 13 are attached to integral flanges on the main
cylindrical body 11 via a plurality of connectors 14, which may be
of the nut and bolt type. Typically, a sealing gasket or washer
will be included between the plates 12 or 14 and the flanges on the
body 11 to make a pressure-tight seal. While the top and bottom
plates in the illustrated embodiment have an essentially flat,
plate-like configuration, in other embodiments, especially for very
large capacity extractors, for example those able to hold 1000 lbs.
or more of solid raw material, one or both of the top and bottom
"plates" may have a dome-like, semi-hemispherical shape to enable
it to withstand higher pressures for a given cross-sectional
thickness. In some embodiments, where disassembly of the vessel is
not critical, the top and/or bottom plates may be integrally formed
with the main cylindrical body, or attached thereto with a
permanent attachment means, such as by welding, to increase the
leak resistance of the vessel and/or eliminate the need for gaskets
and connectors. The vessel, and other components in contact with
the aqueous extract or aqueous solvent, are preferably constructed
of a substance that is relatively inert and non-reactive, such as,
for example stainless steel. The pressure vessel 11 is constructed
and arranged to withstand maximum foreseeable operating pressures.
In one particular embodiment as shown, the vessel 11 can be sized
to hold about 300 lb. of roasted coffee. The internal volume 75 of
the vessel 11, shown in the cross-sectional view of FIG. 4, can
have an internal diameter of about 24 inches, a height of about 48
inches and a volumetric capacity of about 12.5 cubic feet (about 90
gallons). The vessel is supported on a firm, solid surface 16 by a
plurality of support legs 15. In another exemplary embodiment, the
vessel can be sized to hold about 1300 lbs. of roasted coffee, can
have an internal diameter of about 38 inches, a height of about 96
inches, and a volumetric capacity of about 62.5 cubic feet.
[0044] Referring to FIG. 1, coffee, or another solid raw material,
is inserted into the vessel 11 through one or both of raw material
lines 17 and 19 each in communication with an orifice through top
plate 12. Each raw material line includes a valve, 18 on line 17,
and 20 on line 19, that may be opened to insert coffee, and
subsequently closed to seal the vessel 11. Typically, when
inserting the coffee into the vessel 11, the coffee is inserted
through at least one valve, while at least one other valve on the
apparatus is open to the atmosphere to allow displaced air to
escape. In other embodiments, instead of the extractor being
provided with two raw material lines, a single raw material line,
preferably centered in the top plate, may be provided. In some
embodiments, especially for very large extractors, the roasted
coffee may be inserted into the vessel by feeding the roasted
coffee to the raw material line(s) with a screw auger, or other
type, feeder (not shown), which can be mounted to a valve (e.g. 18
and/or 20) included on the raw material feed line. In certain such
embodiments, the screw auger, or other type feeder can be operated
automatically to fill the vessel and discontinue feeding when the
vessel is filled to a desired, predetermined level. In such an
embodiment, the vessel can also include a level sensing probe (not
shown), such as those commonly employed in the food and dairy arts
for detecting the level of materials in tanks, which may be
electrically coupled to a controller that is programmed/configured
to shut off the feeder when a desired, preset level of material is
detected in the extractor.
[0045] The positioning of the raw material lines is more clearly
seen in the top view shown in FIG. 2. In other embodiments, the
lines may be positioned differently from that shown, or the
apparatus may have more, fewer, or no raw material inlet lines. For
example, for some very large extractors, it may be beneficial to
include four, or more, raw material inlet lines to decrease the
time required to fill the vessel. As previously discussed, for some
extractors, a single raw material inlet line may be provided, or,
for small scale extractors, the vessel may have no raw material
inlet lines, in which case, the vessel would need to be
disassembled to be filled with solid raw material.
[0046] While the vessel 11 is being filled with the solid raw
material, in some embodiments, the vessel can be agitated in order
to promote settling of the material within the internal volume 75
of the vessel. For the embodiment shown in FIG. 1, agitation is
provided by a gas-operated bin vibrator 70 connected to an external
supply 41 of gas via line 72 and valve 71. For embodiments
utilizing a bin agitator, it is preferred that the bin agitator is
located at a location positioned at a distance from the bottom
plate 13 about one third the height of the vessel. Other
embodiments of the apparatus 10 do not include the bin vibrator. In
such embodiments, agitation may be provided if desired, for
example, by striking the vessel 11 with a rubber or wooden mallet,
or by placing the apparatus on a vibrating platform. Alternatively,
instead of distributing and settling the solid raw material through
use of agitation, a distributor element could be included within
the internal volume 75 of the vessel 11 to accomplish the same
purpose.
[0047] As shown in FIGS. 1, 2 and 4, the apparatus 10 also includes
an aqueous solvent inlet line 46 (see FIGS. 2 and 4) in fluid
communication with an external source of hot water 32 via line 49
and valve 47. Included on line 46 is a temperature reading device
48 to measure the temperature of the fluid in line 46 and/or the
temperature of internal volume 75 of the vessel 11. In the
embodiment shown, the temperature of internal volume 75 of the
vessel 11 is controlled by controlling the temperature of the hot
water supply 32. In alternative embodiments, especially those
involving relatively small-scale extractors, vessel 11 may be
directly heated, for example by a steam jacket or hot water jacket,
or by integral electrical resistance heating or other heating
methods apparent to the skilled artisan. As shown in FIG. 4,
aqueous solvent inlet line 46 is in fluid communication with a
spray head 63 located within the internal volume 75 of the vessel
11. Spray head is constructed and arranged to relatively evenly
distribute the hot water over the top of the bed of solid raw
material formed in the internal volume 75. A variety of industrial
spray heads can be used for this purpose, such as a multiple stream
solid washing nozzle (Lechler, St. Charles, Ill.). The outlets of
the spray head will preferably be positioned above the typical fill
line 65 of the bed of solid raw material.
[0048] Also included on the top plate 12 of the vessel 11 is a gas
inlet/vent line 33 (see FIG. 1) including a tee connector 34. Tee
connector 34 is in fluid communication with an external source of
compressed gas 41 via lines 39 and 40 and valve 38, and also with
the atmosphere via valve 35 and vent line 36. In alternative
embodiments, instead of having a single inlet line in fluid
communication with both a source of compressed gas and a vent line
via a tee connector, the vessel could instead be provided with two
separate lines that communicate directly with the internal volume
75 of the vessel. Having a single inlet line in fluid communication
with two external lines that are not simultaneously used, as shown,
reduces the number of perforations that need to be made in the
plates 12 and 13 of the vessel 11. While filling the internal
volume 75 of the vessel 11 with aqueous solvent through line 46 in
top plate 12 and/or through line 23 in bottom plate 13, and/or
through tangentially directed line(s) 42 and/or 55, line 33 can be
used to vent or "burp" displaced air from the vessel by closing
valve 38 and opening valve 35. In embodiments including, as
mentioned above, automatic level detection within the vessel, a
level detection probe within the vessel can be configured to detect
the liquid level contained within the vessel, and to control burp
valve 35 and the valve(s) on the aqueous solvent feed line(s)
through which aqueous solvent is fed to the vessel to perform the
above-described fill/burp procedure under automatic control. While
pressurizing the internal volume 75 of the vessel during the
pressure-treat step or while purging residual extract from the bed
after extraction, line 33 can act as a gas inlet line by closing
valve 35 and opening valve 38. Line 39 includes a pressure
measuring device 37 that is used to measure the pressure of the
internal volume 75 of the vessel 11 during operation.
[0049] As shown in FIG. 1, included on bottom plate 13 is an
extract outlet line 23 in fluid communication with the internal
volume 75 of the vessel 11 via a drain hole in bottom plate 13.
Aqueous extract exits vessel 11 via line 23 passes through tee 24,
controllable valve 25, and line 27 to a chiller 28 that reduces the
temperature of the extract to a temperature below room temperature
to prevent degradation to the flavor and/or loss of fragrance. The
chilled extract exits chiller 28 via line 29 and can be collected
in a container 30. In preferred embodiments, container 30 is a
sealable container whose headspace is filled and/or flushed with an
inert gas, such as nitrogen, in order to prevent exposure of the
extract to atmospheric oxygen. As described in more detail below in
the context of FIGS. 6-8, container 30 can also serve as the feed
container to the inventive solvent-removal filtration system
utilized, in some embodiments, for concentrating the coffee
extract. Also in fluid communication with tee 24 and line 23 via
valve 26 and line 31 is hot water supply 32; hot water supply line
31 can be used, in certain embodiments, for filling the vessel with
aqueous solvent through line 23 after filling the vessel with
roasted coffee, as previously described, and, in addition, these
lines are used in connection with the novel spent material flush
out methods described in more detail below.
[0050] In order to prevent the solid raw material from exiting the
vessel via line 23 during flow-through extraction, a filter element
is included within vessel 11 upstream of line 23. A preferred
arrangement of filter element is shown in FIG. 3 and, in
cross-section, in FIG. 4. The preferred filter element includes of
a porous screen 58 having openings therein that are small enough to
retain essentially all of the solid raw material. In one preferred
embodiment, the porous screen comprises a commercially available
(e.g. U.S. Filter, Johnson Screen Division, St. Paul, Minn., Model
63V, having a slot size of 0.020'') wedge wire type screen, with a
surface oriented facing the bed of solid raw material, having about
25% open space. As shown more clearly in FIG. 4, porous screen 58
is supported by bottom plate 13, which plate includes a plurality
of channels and grooves 59 constructed and arranged to direct the
flow of aqueous extract that passes through porous screen 58 to
aqueous extract outlet line 23. Porous screen 58 provides a
support, and means of retention for the bed of solid raw material
and has a diameter that is preferably essentially equal to the
internal diameter of vessel 11. Porous screen 58 can be attached to
bottom plate 13 via screws 67, or any other appropriate connecting
means. In some other embodiments, the filter element may be
positioned elsewhere in the internal volume 75. In other
embodiments, the filter element could be a smaller screen or filter
positioned directly upstream of, or even within extract outlet line
23. A wide variety of arrangements of the filter element are
possible as would be apparent to the skilled artisan; all of which
are included within the scope of the invention.
[0051] As previously mentioned, extraction apparatus 10 also
includes a novel arrangement of components for flushing spent solid
raw material from the internal volume 75 of the vessel 11, and for
cleaning out the vessel after an extraction has been performed and
prior to a subsequent extraction. The arrangement of components
illustrated allows spent raw material to be flushed from extraction
apparatus 10, and allows for clean-out without the need for
disassembly of the apparatus. In the illustrated embodiment, as
shown in FIG. 1, the wash-out system includes spent material outlet
waste line 21, including valve 22, that is in fluid communication
with a waste collection system, such as a sewer. As shown in FIG.
4, outlet port 60, opening into the internal volume 75 of the
vessel 11 from line 21, is preferably positioned directly above
porous screen 58. In alternative embodiments, not shown, instead of
outlet port 60 comprising an orifice through the side wall of
vessel 11 positioned above the screen, the outlet port may instead
be located in the bottom plate and communicate with the internal
volume of the vessel, for the purposing of flushing out spent solid
raw material, through a hole in the porous screen positioned
adjacent to, and in fluid communication with, the outlet port in
the bottom plate. For such alternative embodiments, a gasket, or
other sealing means, can be included to fluidically isolate the
spent material outlet port from the downstream side of the porous
screen, where extract collects and flows from the extractor, in
order to prevent contamination of the collected extract with spent
solid raw material, as would be apparent to those of ordinary skill
in the art.
[0052] A preferred wash out configuration includes a fluid supply
line constructed and arranged to back-flush the filter element. In
the illustrated embodiment, the back flush is performed through
line 23 by first closing valve 25, and then opening valve 26 so
that a fluid, in the illustrated embodiment hot water from
pressurized hot water supply 32, will enter the vessel 11 via line
23, which now acts as an inlet flush line, and thereby back flush
the porous screen 58. Typically, valve 22 will be open during the
flush-out procedure to allow spent material to be removed from the
vessel 11; although, in some embodiments, valve 22 may be closed
during at least part of the flush-out procedure to allow the
internal volume 75 of the vessel 11 to at least partially fill with
liquid in order to disperse and fluidize the spent material. In
alternative embodiments, line 31 may also be in fluid communication
with a source of pressurized gas. In such embodiments, either gas,
liquid, or a two-phase gas-liquid fluid can be used to back flush
the filter element and wash out the spent solid raw material.
[0053] Also included in the preferred embodiment are additional
tangential flush lines 42 and 55 (see FIGS. 1 and 3) which are in
fluid communication with a source of pressurized cold water 45 via
valve 43 and line 44 for flush line 42, and valve 56 and line 57
for flush line 55, and with hot water supply 32 via connection to
lines 44 and 57, for example by connector line 44a and three-way
valve 43a. As previously discussed, these tangential flush lines
can also be advantageously used as hot aqueous solvent fill lines
during initial filling of the vessel with aqueous solvent after
filling with solid raw material at the beginning of the extraction
process. Both lines 42 and 55 are positioned to be roughly tangent
to the cylindrical wall of vessel 11 with openings (e.g. see FIG. 4
for opening 61 of line 55) into the internal volume 75 of the
vessel 11 positioned vertically above the porous screen 58 at about
the same height, in the illustrated embodiment, as the outlet port
60 to spent material outlet line waste 21. The tangential
orientation of the flush lines 42 and 55 with respect to the vessel
walls tends to create a swirling, vortex-like flow pattern of wash
fluid within the vessel, which assists in thoroughly removing the
spent material from the vessel 11 via line 21. In addition, at
least one of the tangential flush lines (line 55 in the illustrated
embodiment) is preferably positioned so that the opening 61 of the
line in the vessel wall directs a stream of flush fluid obliquely
incident upon the outlet port 60, through which spent material
exits the vessel 11, in order to drive the slurried material
through line 21 to waste and prevent plugging of outlet port 60. In
other embodiments, more than two tangential flush lines may be used
to improve removal of spent material, for example for very large
extractors, or alternatively only a single line may be used. For
small extractors, tangential flush lines are typically not required
to effectively remove the spent material from the vessel.
[0054] Also included, in the illustrated embodiment, and seen most
clearly in FIGS. 2 and 4, is an optional wash down line 62 through
top plate 12. Wash down line 62 is in fluid communication with a
supply of pressurized cold and hot water via tee 50, and valve 51
and line 53 (cold water), or valve 52 and line 54 (hot water). Wash
down line 62 is preferably connected to a rotating spray nozzle 64
that is positioned within internal volume 75 of the vessel 11.
Rotating spray nozzle 64, when supplied with pressurized fluid,
will rotate and spray fluid in order to effectively wash down the
walls and internal surface of the top plate 12 and the vessel 11. A
variety of commercially available rotating spray nozzles can be
used for this purpose. The illustrated embodiment employs a
whirling tank nozzle (Lechler, St. Charles, Ill.). Other
embodiments may include additional wash down lines and rotating
spray nozzles, while, in yet other embodiments, wash down line 62
may be eliminated, and wash down may be performed by utilizing line
46 and spray head 63 alone. In some embodiments, the water employed
for washing purposes may include one or more cleaning and/or
corrosion inhibiting agents as known in the art.
[0055] Operation of the Extraction Apparatus
[0056] With reference to the apparatus illustrated by FIGS. 1-4, an
exemplary coffee extraction procedure using the above described
apparatus can proceed as follows. At the start of the procedure,
all valves are in a closed position. The vessel 11 is then
preheated by opening valve 52 to establish a flow of pressurized
hot water into the vessel through rotating spray nozzle 64. When
the pressure within the vessel, as read by pressure measuring
device 37, is approximately equal to that of the hot water supply
pressure, valve 25 downstream of extract outlet line 23 is opened
to establish a flow of hot water to drain or chiller 28, and then
valve 52 is closed. Valve 38 is then opened to supply pressurized
gas, preferably an inert gas, such as nitrogen, to the vessel via
line 33. The gas flow is maintained until no more liquid is
observed leaving the vessel. The gas flow is then discontinued by
closing valve 38, and the vessel is equilibrated to atmospheric
pressure. Valve 25 downstream of extract outlet line 23 is left
open.
[0057] A desired quantity of dry coffee is next added to the vessel
by opening valves 18 and 20 on raw material lines 17 and 19 and
pouring or feeding coffee into the vessel through lines 17 and 19
until the vessel is essentially full. The dry coffee can then be
settled by opening valve 71 to supply gas flow to bin vibrator 70,
or alternatively, tapping the vessel with a mallet, if desired.
Alternatively, the coffee can be settled without agitation of the
vessel by briefly opening valve 52 and/or 47, and/or 26, and/or 43,
and/or 56 to apply hot water to the coffee at one or more intervals
during the addition of dry coffee, or after the coffee has been
added, to moisten and settle the coffee. If desired, more coffee
may now be added to more completely fill the vessel before closing
valves 18 and 20. Valve 47 is then partially opened to supply
pressurized hot water to the vessel via aqueous solvent inlet line
46. Upon the first sign of extract discharge from line 29, valve 25
downstream of extract outlet line 23 is closed and the vessel is
filled with a desired quantity of hot water. Valve 35 on vent line
36 is at least partially opened, either manually or via automatic
control, at some point during the process of filling the vessel
with water to "burp" out gas; the valve 35 is closed when extract
is observed to flow from line 36. The volume of hot water added to
the coffee is preferably equal to or greater than the void volume
of the bed of coffee so that all of the coffee is wetted. In some
embodiments, the volume is essentially equal to the void volume
present in the bed. As discussed above, the vessel can also be
filled with hot aqueous solvent at this stage through one or more
of lines 46, 23, 42, and 55. The vessel is then further
pressurized, either with pressurized hot water by opening valve 47,
or with pressurized gas by opening valve 38, to a desired pressure
(typically about 40-132 psig) for performing the static
pressure-treat step. The pressure is maintained in the vessel
without flow for a desired period of time (typically about 10-30
min.). Next, valve 25 downstream of the extract outlet line 23 is
controllably opened to initiate a desired flow rate of extract
through line 27 and chiller 28 and into collection container 30.
For some embodiments during this step, depending on the desired
strength of the extract and degree of extraction, valve 47 can be
opened and a measured quantity of hot water can be added to the
vessel to further extract the coffee within the vessel via a
flow-through extraction step. During such flow-through extraction,
the pressure within the vessel can be controlled by adjusting valve
25 on the extract outlet line 23, and/or valve 47 on the hot water
inlet line 46. For embodiments where additional hot water has been
added after the pressure treat step, after the desired quantity of
additional solvent water has been supplied during the flow-through
extraction, valve 47 is closed to discontinue flow from the hot
water supply. Valve 38 is then opened so that compressed gas enters
the vessel via line 33 in order to purge residual extract from the
void volume of the bed of coffee. Valve 47 is closed when gas flow
is observed from extract collection line 29. At this point,
extraction is complete and the vessel may be reused for a
subsequent extraction with the same charge of coffee to produce an
extract having more bitter/acidic flavor/fragrance characteristics
of a more exhaustively extracted roasted coffee, or the spent
coffee can be removed from the vessel. For embodiments where a
maximum-strength extract is desired, the extract can be purged from
the bed with the gas flow immediately after the pressure-treat step
without supplying additional hot solvent water for a flow-through
extraction step.
[0058] In order to remove the spent grounds from the vessel, valve
25 on the extract outlet line 23 is closed and valve 22 on spent
material waste line 21 is opened. Valve 26 is then opened to back
flush the porous screen 58 with pressurized water through line 23;
valves 43 and 56 are opened to supply pressurized water flow to
tangential flush lines 42 and 55 respectively, and valve 51 or 52
is opened to supply pressurized cold or hot water to rotating spray
nozzle 64 via line 62. After the flow of liquid exiting the waste
line 21 is observed to be clear and clean, the valves supplying
pressurized water to the various lines for flush out are closed;
valve 22 on waste line 21 is closed, and the process is complete.
The extract exit line 27, chiller 28, and extract collection line
29 can also be flushed by opening valve 25 followed by valve 26 to
direct pressurized water from source 32 through line 31, valve 26,
tee 24, valve 25, line 27, chiller 28, and line 29.
[0059] As discussed previously, the invention also provides methods
for removing excess solvent from consumable extracts in order to
concentrate the extracts with respect to a dissolved or suspended
consumable material. It should be understood that the inventive
filtration-based concentration methods described herein can be
utilized for concentrating a wide variety of consumable extracts
produced from extracting a wide variety of solid raw materials,
such as those discussed previously in the context of the inventive
extraction methods. It should also be understood that, while in
some preferred embodiments, the inventive concentration methods are
utilized for concentrating extracts produced using the
above-described inventive extraction methods and apparatuses, the
novel concentration methods described herein can also, in other
embodiments, be utilized for concentrating consumable extracts
produced by a wide variety of other extraction methods for forming
consumable extracts known in the prior art. As with the
above-discussed extraction methods, the inventive extract
concentration methods will be described below with reference to a
particular embodiment involving the concentration of an aqueous
extract of roasted coffee; however, it should be understood that
the methods and apparatuses described herein are not so limited and
that the methods and apparatuses may be employed with a wide
variety of other consumable extracts produced by a wide variety of
extraction methods within the scope of the present invention.
[0060] FIG. 5 is a conceptual diagram of a portion of
filtration-based system for concentrating a consumable extract, for
example a coffee extract as produced by the extraction methods
described above. FIG. 5 shows a section of a filter 100 including a
filter medium 102, which separates the filter into a retentate side
104 and a permeate side 106. The term "filter" as used herein
refers broadly to any apparatus or system containing a filtration
medium and able to perform filtration of a liquid. The term
"filtration medium" as used herein refers to any medium, material,
or object having sufficient hydraulic permeability to allow at
least one component, for example a solvent, of a liquid solution or
suspension, for example a coffee extract, to pass through the
medium, while, at the same time, retaining and preventing passage
of at least one other component of the solution or suspension, for
example a dissolved solute component. A wide variety of filters and
filter media may be used, according to the invention, for
concentrating consumable extracts, for example coffee extracts.
[0061] Filters that may be utilized according to the invention can
include a wide variety of configurations as known in the art, for
examples, gel permeation filters, and membrane-based filters in a
wide variety of configurations, such as flat sheet filters, hollow
fiber filters, spiral filters, tube membrane filters, and other
configurations as apparent to those of ordinary skill in the art.
Preferred filters employ a filtration medium comprising a
semipermeable membrane(s). Such membranes can be fabricated from a
wide variety of materials, such as ceramics and other inorganic
materials, or organic materials, such as polymers. Certain
preferred embodiments of the invention utilize a filtration medium
comprising a semipermeable polymeric membrane(s). Such polymeric
membranes can be fabricated from a wide variety of polymeric
materials and can be constructed to have a wide variety of porosity
and molecular size exclusion characteristics. Such membranes are
well known in the filtration arts, and are widely commercially
available. Polymeric membranes can potentially be constructed, for
example, from polymers including, but not limited to, polyamides,
cellulose and/or cellulose esters, polysulfone, polycarbonate,
polyesters, polyethylene oxide, polypropylene oxide, polyvinylidene
fluoride, poly(tetrafluoroethylene), poly(acrylates), others, and
in co-polymers and/or combinations as known in the filtration and
membrane separation arts.
[0062] Referring to FIG. 5, the basic steps of the inventive
concentration method can involve supplying an extract to be
concentrated to the retentate side 104 of filter 100, passing a
permeate comprising at least a portion of the solvent component of
the extract through filtration medium 102, as shown by arrow 108,
and collecting the concentrated and solvent-reduced extract from
the retentate side 104 of the filter, and, optionally, collecting
the permeate from the permeate side 106 of the filter. Filter 100
may, in some embodiments, be operated in a dead-end mode, with
essentially no flow or very little flow of retentate directed
tangential to filter medium 102, or, in more preferred embodiments,
the filter can be operated in a cross-flow mode as shown, with a
component of retentate flow (arrows 109) directed tangentially to
the filtration medium, in order to prevent fouling and increase the
filtration efficiency of the filter.
[0063] Filter medium 102 is preferably selected to have a porosity
and molecular weight cutoff able to allow passage of a solvent
component of the extract, for example water, while retaining on the
retentate side of the filter dissolved or suspended solutes which
form flavor and/or fragrance components of the extract. For
embodiments where the method is used for de-watering a coffee
extract, filter membrane 102 is preferably selected so that it is
able to freely pass water, while, at the same time, retaining, on
the retentate side, a substantial fraction of the dissolved coffee
solids in the extract. A "substantial fraction" as used herein in
the present context refers to a fraction of coffee solids that is
necessary to impart to the retained extract an "effective amount"
of varietal components, as defined previously. In some preferred
embodiments, at least 90% of the coffee solids are retained, and in
even more preferred embodiments, essentially all of the dissolved
solids comprising flavor and/or fragrance components are retained
on the retentate side of the filter by the filtration membrane. For
preferred embodiments involving de-watering of coffee extracts, the
filtration membrane 102 comprises a reverse osmosis membrane or a
nanofiltration membrane. A "reverse osmosis membrane" as used
herein refers to a membrane having an average pore size of less
than about 0.003 .mu.m and a molecular weight cutoff of less than
about 1,000 Da. A "nanofiltration membrane" as used herein refers
to a membrane having an average pore size within the range of
between about 0.001 .mu.m and about 0.01 .mu.m, with a molecular
weight cutoff within the range of between about 300 Da and about
20,000 Da. In one preferred embodiment, filter membrane 102
comprises a polyamide nanofiltration membrane, in another preferred
embodiment, the filter membrane comprises a spiral-wound,
multi-layer, thin film composite reverse osmosis membrane such as
FILMTEC.RTM. reverse osmosis membranes available from The Dow
Chemical Company.
[0064] The concentration method, according to the invention, for
forming a concentrated coffee extract via de-watering a more dilute
precursor extract can proceed by supplying the relatively dilute
coffee extract to the retentate side 104 of filter 100 at a
pressure P.sub.1 sufficiently in excess of pressure P.sub.2 on
permeate side 106 of the filter to force solvent through membrane
102 while retaining a substantial fraction of coffee solvents on
retentate side 104, and, thus, increasing the concentration c.sub.1
of dissolved coffee solids in the retentate above that of the
concentration in the precursor coffee extract. The filtration
process can be continued until a desired concentration c.sub.1 is
achieved. The system can be monitored by, for example, measuring
the volume of permeate collected from permeate side 106 of the
filter and comparing the volume of permeate collected to the
initial volume of coffee extract before commencement of the
filtration process and/or by measuring the conductivity of the
retentate and determining the dissolved solids concentration by
comparison with a calibration curve. For example, for embodiments
where it is desired to reduce the volume of solvent in the initial
coffee extract by a factor of 2, and thus increase the
concentration of coffee solids in the concentrated extract by
approximately a factor of 2, the filtration process can be
continued until a volume of permeate approximately equal to one
half the initial volume of extract supplied to the retentate side
of the filter is collected.
[0065] The filter size, for example as measured by the total area
of the planar surface 110 of membrane 102 available for filtration,
the applied differential pressure (P.sub.2-P.sub.1), flow rates,
and other operating parameters of the filter, as well as the
molecular weight cutoff and pore size of the filter membrane, must
be selected according to the needs of each particular desired
application. The selection of such operating parameters can be
based upon the total volume of extract desired to be concentrated
within a particular time period, the concentration and size of the
dissolved and/or suspended components in the extract which are
desired to be retained, the particular configuration of the filter,
and other factors as apparent to those of ordinary skill in the
filtration arts, and as described, for example in many standard
texts such as Perry's Chemical Engineers' Handbook (Sixth Edition,
Robert H. Perry, Don W. Green, and James O. Maloney, Eds., 1984,
Chapter 17), incorporated herein by reference. As described below
with reference to FIGS. 6-8, many filtration systems for performing
reverse osmosis or nanofiltration are commercially available and
are sized and designed for processing a wide variety and quantities
of liquid solutions/suspensions.
[0066] The particular selection of operating parameters must be
made, for a particular application, by routine experimentation and
optimization. For example, screening tests may be performed for
selecting appropriate types of filtration membranes and molecular
weight cutoffs by performing a trial filtration of a dilute, for
example beverage strength, coffee extract with a particular
membrane until a desired degree of de-watering is obtained,
followed by collecting the concentrated extract from the retentate
side of the filter, reconstituting the concentrated extract with a
volume of fresh solvent water equal to the volume of permeate
removed during filtration, and comparing the taste and/or flavor
characteristics of the reconstituted extract to that of the
initial, beverage-strength extract, for example by cupping as
described previously. Operating pressures, filter sizes, flow
rates, and other operating parameters may be selected on the basis
of well known principles of membrane filtration/separations,
described in many well known and readily available texts describing
filtration/reverse osmosis, for example in Perry's Chemical
Engineers' Handbook referenced above and McCabe, Smith, and
Harriott, Unit Operations of Chemical Engineering, Fourth Edition,
Kiran Verma and Madelaine Eichberg, Eds., 1985, incorporated herein
by reference, combined with routine experimentation and
optimization. Typically, for a given filtration membrane, having a
molecular weight cutoff and porosity selected as described above,
the total membrane area is selected to provide a desired range of
permeate throughput (i.e., volume filtered/time) within an
acceptable range of differential pressure, as dictated by the
material limitations of the filtration medium and filter system
components.
[0067] As shown in FIG. 5, upon filtration of a coffee extract to
form a more concentrated coffee extract, over time, a layer of
coffee solids 112 may have a tendency to build up on the retentate
side 110 of filter membrane 102. This can be undesirable from the
standpoint both of decreasing the filtration rate through membrane
102 at a given differential pressure, and from the standpoint of a
loss of coffee solid concentration c.sub.1 in the retentate
collected from retentate side 104 of the filter. In some preferred
embodiments, at one or more points during the filtration process,
membrane 102 can be back-flushed by supplying, for a brief period,
a relatively small volume of a back-flush solvent (which, in some
embodiments, may comprise permeate collected during the filtration
process) to the permeate side 114 of membrane 102, and forcing the
back-flush solvent through membrane 102 from permeate side 106 of
the filter to retentate side 104 of the filter, in the direction of
arrow 116, by creating a pressure P.sub.2 on the permeate side
exceeding pressure P.sub.1 on the retentate side of the filter. In
this way, coffee solids forming a layer 112 on membrane 102 can be
dislodged from the membrane to improve its overall filtration rate,
upon subsequent filtration, and also to re-suspend coffee solids
112 in the concentrated coffee extract present on retentate side
104 of the filter. Thus, using such a back-flush procedure can
increase the total recovery of, and concentration of, coffee solids
in the de-watered extract, which can lead to formation of a more
valuable de-watered extract product with enhanced retention of the
flavor/fragrance characteristics of the initial precursor coffee
extract before concentration. It is also contemplated that the
permeate collected from permeate side 106 of the filter during the
de-watering of coffee extract can, in certain embodiments, contain
commercially valuable components, for example caffeine. For such
embodiments, this permeate may be collected and utilized as a
component or ingredient in other food or pharmaceutical
products.
[0068] One illustrative embodiment of a filtration system for use,
according to the invention for de-watering and concentrating a
coffee extract is shown in FIG. 6. Filtration system 150, as shown,
is representative of a variety of commercially available reverse
osmosis/nanofiltration systems available, for example, from the
PROSYS Corporation (Chelmsford, Mass.). In one particular
embodiment of the invention, filtration system 150 comprises a
modified PROSYS Model No. 400 Series Reverse Osmosis System having
a nominal design permeate flow rate of 1 gal./min. The system, as
configured in the illustrated embodiment, is constructed from
food/pharmaceutical grade materials. The system may further
include, in some embodiments, a variety of additional valves,
switches, pressure gauges, transducers, temperature probes,
electronic/microprocessor-based monitoring/process control hardware
and software, etc., in addition to the particular components
illustrated, as would be apparent to those of ordinary skill in the
reverse osmosis/nanofiltration arts. System 150, as configured in
the illustrated embodiment, includes four filtration cartridges
152, 154, 156, and 158, which are arranged in a parallel
configuration. Each of the filter cartridges, as illustrated,
includes a Model No. TFC.RTM.-4921S Spiral-Wound Filter Cartridge
(Koch Membrane Systems, Wilmington, Mass.). The filtration
cartridges each include about 7.5 m.sup.2 of filter membrane area.
The filter membrane is configured in a spiral-wound fashion with a
fiberglass outerwrap, and the semi-permeable membrane comprises a
polyamide membrane of the nanofiltration type. The maximum
operating pressure for the membrane cartridges is about 350 psi
with a typical operating pressure of about 80 psi. System 150
further includes a 5 .mu.m cartridge prefilter 160 upstream of
filter cartridges 152, 154, 156, and 158. In the illustrated
embodiment, extract is pressurized and supplied to the filter
cartridges by means of a pump 162, which, in the illustrated
embodiment, comprises a multi-stage centrifugal pump with stainless
steel wetted components. In other embodiments, pump 162 may be
supplemented or replaced by a system for pressurizing the
container/vessel 30 holding extract 164 to be concentrated. In one
preferred embodiment, such an extract pressurization system can
comprise a source of compressed gas 166 coupled to container 30 via
line 168 and valve 170, which is configured to supply compressed
gas at a sufficient pressure for driving extract through filtration
system 150. For embodiments where extract 164 is pressurized with
an external source of pressurized gas, it is preferred that the
pressurized gas comprise an inert gas, for example nitrogen. In
preferred embodiments, extract 164 in container 30 is maintained in
contact with and blanketed by an inert gas supplied be source 166
during processing in order to minimize its exposure to oxygen. The
inert gas from source 166 can also, in some embodiments, be used at
the end of processing, after collection of the concentrated extract
product from the system, to "blow out" residual retentate from the
lines of the system and the filtration cartridges for
collection.
[0069] System 150 can operate as follows for de-watering and
concentrating a coffee extract, according to the invention.
Unconcentrated extract 164 in container 30 can be produced, for
example, as described above by utilizing the inventive extraction
methods and apparatuses. "Unconcentrated" extract as used herein
refers specifically to an extract forming a feed stream to the
retentate side of the filters contained within the system. It
should be understood that such "unconcentrated" extracts will, in
many cases, already, as produced from the inventive extraction
methods and apparatus, have a level of coffee solids concentration
exceeding that typical for typical beverage-strength extracts.
Conversely, a "concentrated" extract, as used in the following
description, refers to an extract comprising a water-reduced (i.e.
de-watered) retentate product recovered from the retentate side of
the filters contained within the system. As described previously,
in some preferred embodiments, unconcentrated extract 164 can
comprise an extract produced from a second or subsequent extraction
step of a given charge of roasted coffee. For embodiments where
extract 164 is produced from a second or subsequent extraction step
of a given charge of roasted coffee, typically, the concentration
of coffee solids in the extract will be lower, and the degree of
dilution with water will be higher, than for extracts produced
during the first-pass extraction of the roasted coffee. It is,
therefore, sometimes desirable to concentrate the second, or
subsequent pass extract so that it has a concentration of coffee
solids and degree of dilution that is similar to that of the
first-pass extract. In this way, as described in more detail below,
the extracts produced according to the invention during the
first-pass extraction may be blended with extracts produced during
a second or subsequent stage extraction, which have been de-watered
to have an overall concentration similar to that of the first-pass
extract, to form blended coffee extracts without substantially
diluting the overall concentration of coffee solids in the
first-pass extract.
[0070] Extract 164 can be fed, for example by gravity, through
valve 172 and line 176 to pump 162 where it is pressurized to the
operating pressure of filtration cartridges 152, 154, 156, and 158.
The extract then passes from pump 162 through line 178 and through
pre-filter 160 to manifold 180 including a pressure gauge or
transducer 182 thereon for monitoring the retentate side pressure
of filtration cartridges 152, 154, 156, and 158. In other
embodiments, additional pressure gauges/transducers may be located
directly on the individual filtration cartridges 152, 154, 156, and
158. In addition, while in the illustrated embodiment filtration
cartridges 152, 154, 156, and 158 are connected in parallel to a
manifold 180, in other embodiments, the filtration cartridges may
instead be connected in series with respect to each other. From
manifold 180, extract 164 passes through each of filtration
cartridges 152, 154, 156, and 158 via line 184 and valve 186, line
188 and valve 190, line 192 and valve 194, and line 196 and valve
198 respectively. Unconcentrated extract 164 is fed to the
retentate side of the filter cartridges. While flowing through the
retentate side of the filter cartridges, at least a portion of the
solvent component of the extract passes through the filtration
membrane to the permeate side of the filtration cartridges, thus
forming a more concentrated coffee extract on the retentate side of
the filter cartridges and a relatively dilute or coffee solid free
permeate on the permeate side of the filter cartridges. The
concentrated coffee extract retentate then flows out of the filter
cartridges and into a concentrated extract manifold 199 via line
200 and valve 202, line 204 and valve 206, line 208 and valve 210,
and line 212 and valve 214 for filtration cartridges 152, 154, 156,
and 158 respectively. Concentrated extract manifold 199 may include
a pressure gauge/transducer 216 thereon for monitoring the pressure
on the retentate sides of the filter cartridges. The concentrated
coffee extract in manifold 199 flows via line 218 and valve 220 to
collection container 222, for containing concentrated extract
224.
[0071] In some preferred embodiments for operating filtration
system 150, unconcentrated extract 164 passes through filtration
cartridges 152, 154, 156, and 158 only single time to form
concentrated extract 224 in a single-pass through the system. In
other embodiments, system 150 may be operated as a multi-pass
system, where, in such embodiments, the concentrated extract is
recycled back to container 30 via line 226 and valve 228. For such
embodiments, extract would continue to be pumped from container 30,
through the filter cartridges, and recycled to container 30 until a
desired quantity of solvent has been removed, as permeate, and a
desired level of concentration of the extract contained in
container 30 has been achieved.
[0072] Permeate is collected from the filter cartridges via lines
230, 232, 234, and 236 and flows into manifold 238, which can have
a pressure gauge/transducer 240 thereon, and into permeate
collection container 242. As previously discussed, permeate 244 may
be saved and utilized as an ingredient for additional
food/pharmaceutical products or, may be discarded. In another
preferred embodiment, especially where the solvent water comprising
permeate 244 has been substantially demineralized by passage
through filtration cartridges 152, 154, 156, and 158, aqueous
permeate 244 can be beneficially used as an extraction solvent for
performing an extraction of fresh, or previously extracted, roasted
coffee, and, for such purposes, may be recycled back to line 46 on
extraction system 10, as shown previously in FIGS. 1 and 2. The
amount of permeate removed form the extract during concentration
procedure depends, as previously discussed, on the desired final
concentration of the concentrated extract. For some preferred
embodiments involving a single-pass operating mode, and where a
highly concentrated extract is desired, at least about 50% of the
solvent component of the extract supplied to the retentate side of
the filter cartridges is passed to the permeate side of the filter
cartridges, or, for multipass/multicycle embodiments, at least 50%
of the solvent component of the initial precursor unconcentrated
extract is removed by the system during the multipass filtration
procedure. Also, as discussed previously, for some embodiments,
filtration cartridges 152, 154, 156, and 158 may be briefly
back-pulsed or back-flushed, for example by reversing pump 162
and/or supplying a pressurized quantity of permeate or other
back-flush solvent to manifold 238. For such embodiments, the
filtration media in the filtration cartridges may be at least
partially cleaned and regenerated, and additional coffee solids may
be collected from the retentate side of the filter cartridges for
addition to concentrated extract 224 during the back-flush
procedure.
[0073] A second illustrative embodiment of a filtration system for
use, according to the invention for de-watering and concentrating a
coffee extract is shown in FIG. 7. Filtration system 300, in one
particular embodiment of the invention, comprises a modified Fluid
Solutions Model No. 10037 Reverse Osmosis System (Fluid Solutions,
Inc. Lowell, Mass.) having a nominal design permeate flow rate of
about 12-15 gal./min. The system, as configured in the illustrated
embodiment, is constructed from food/pharmaceutical grade
materials. The system may further include, in some embodiments, a
variety of additional valves, switches, pressure gauges,
transducers, temperature probes, electronic/microprocessor-based
monitoring/process control hardware and software, etc., in addition
to the particular components illustrated, as would be apparent to
those of ordinary skill in the reverse osmosis/nanofiltration arts.
System 300, as configured in the illustrated embodiment, includes
five filtration cartridges 302, 304, 306, 308, and 310. Cartridges
302, 304, and 306 are arranged in parallel and are connected in
series with cartridges 308 and 310, which are connected in parallel
with each other. Each of the filter cartridges, as illustrated,
includes three FILMTEC.RTM. Model No. BW30-4040 spiral-wound filter
membrane elements. The filter membrane elements each include about
6.5 m.sup.2 of filter membrane area. The maximum operating pressure
for the filter membrane elements is about 600 psi with a typical
operating pressure of between about 250-400 psi. System 300 further
includes a 5 .mu.m cartridge prefilter 312 upstream of filter
cartridges 302-310. In the illustrated embodiment, extract is
pressurized and supplied to the filter cartridges by means of
booster pump 314 and R/O pump 316. In other embodiments, pump 314
and/or 316 may be supplemented or replaced by a system for
pressurizing the container/vessel 30 holding extract 164 to be
concentrated. In one preferred embodiment, such an extract
pressurization system can comprise a source of compressed gas 166
coupled to container 30 via line 168 and valve 170, which is
configured to supply compressed gas at a sufficient pressure for
driving extract through filtration system 300. For embodiments
where extract 164 is pressurized with an external source of
pressurized gas, it is preferred that the pressurized gas comprise
an inert gas, for example nitrogen. Container 30, as illustrated,
also includes an inlet line 318, connected to a city water supply
via valve 320 and an outlet line 322 for draining the container
through valve 324. In preferred embodiments, extract 164 in
container 30 is maintained in contact with and blanketed by an
inert gas supplied be source 166 during processing in order to
minimize its exposure to oxygen. The inert gas from source 166 can
also, in some embodiments, be used at the end of processing, after
collection of the concentrated extract product from the system, to
"blow out" residual retentate from the lines of the system and the
filtration cartridges for collection.
[0074] System 300 can operate as follows for de-watering and
concentrating a coffee extract, according to the invention.
Unconcentrated extract 164 in container 30 can be produced, for
example, as described above by utilizing the inventive extraction
methods and apparatuses. Extract 164 can be fed, for example by
gravity, through valve 326 and line 328 to booster pump 314.
Alternatively, or concurrently, extract can be fed to the system
directly from the outlet line of the extractor via line 330 and
valve 332. The extract is pressurized by booster pump to a
pressure, measured by pressure gauge 334, sufficient to pass the
extract through the prefilter 312. Pressure drop across the
prefilter can be determined by comparison of the pressure measured
downstream of the prefilter by pressure gauge 336 to that measured
upstream by gauge 334. A conductivity meter 338 is included to
enable the determination of the concentration of solids in the
extract prior to de-watering in cartridges 302, 304, 306, 308, and
310, as previously discussed.
[0075] The extract is then pressurized to the operating pressure of
filtration cartridges 302, 304, 306, 308, and 310 by R/O pump 316.
The extract then passes from pump 316 through line 340 and through
throttling valve 342, including located upstream and downstream
thereof pressure gauges 344 and 346 respectively, to manifold 348.
In other embodiments, pressure gauges/transducers may be located on
the manifold or directly on the individual filtration cartridges
302, 304, and 306. From manifold 348, extract 164 passes through
each of filtration cartridges 302, 304, and 306 via line 350, line
352, and line 354 respectively. Unconcentrated extract 164 is fed
to the retentate side of the filter cartridges. While flowing
through the retentate side of the filter cartridges, at least a
portion of the solvent component of the extract passes through the
filtration membrane to the permeate side of the filtration
cartridges, thus forming a more concentrated coffee extract on the
retentate side of the filter cartridges and a relatively dilute or
coffee solid free permeate on the permeate side of the filter
cartridges. The concentrated coffee extract retentate then flows
out of the filter cartridges and into a concentrated extract
manifold 356 via line 358, line 360, and line 362 for filtration
cartridges 302, 304, and 306 respectively. The concentrated coffee
extract in manifold 356 flows via line 364 to inlet manifold 366
which feeds filter cartridges 308 and 310 via lines 368 and 370
respectively. The extract is then further concentrated by filter
cartridges 308 and 310 to produce a concentrated a coffee extract
retentate which flows out of the filter cartridges 308 and 310 into
a concentrated extract manifold 372 via lines 374 and 376. The
concentrated extract then flows via line, including pressure gauge
380 thereon, through throttling valve 382 to chiller 384. Included
on line 378 downstream of throttling valve 382 is a flow meter 386
for measuring volumetric fluid flow of the retentate and a
conductivity meter 388 for determination of solids content of the
concentrated extract. If the solids concentration of the retentate
stream, as determined from the conductivity measurement or
otherwise, meets the desired product value, then the concentrated
extract can be collected as final product from line 390 by opening
valve 392; otherwise, the extract can be recycled to tank 30 via
opening valve 394 on line 396 for further processing.
[0076] Permeate is collected from the filter cartridges via lines
398, 400, 402, and 404 and flows into manifold 408. Manifold 408,
in turn, feeds permeate line 410, which has a flow meter 412
thereon. Permeate can either be sent to drain or collection via
opening valve 414 on line, or, if desired, recycled to tank 30 via
opening valve 418 on line 420. As discussed previously, for some
embodiments, filtration cartridges 302, 304, 304, 306, 308, 310 may
be briefly back-pulsed or back-flushed, for example by reversing
pump 316 and/or supplying a pressurized quantity of permeate or
other back-flush solvent to manifold 408. For such embodiments, the
filtration media in the filtration cartridges may be at least
partially cleaned and regenerated, and additional coffee solids may
be collected from the retentate side of the filter cartridges for
addition to the product concentrated extract during the back-flush
procedure.
[0077] A third illustrative embodiment of a filtration system for
use, according to the invention for de-watering and concentrating a
coffee extract is shown in FIG. 8. Filtration system 500, is
similar in construction and operation to system 300 illustrated
previously in FIG. 7, except for the size and capacity of the
system and the arrangement of the filter cartridges. Components of
system 500 that are similar in design and function to corresponding
components of system 300 discussed previously (although potentially
differing in size and design so as to accommodate the larger size
and capacity of system 500, as would be apparent to those of
ordinary skill in the art) are given the same figure labels as in
FIG. 7 and are not separately discussed herein. Filtration system
500 in one particular embodiment of the invention, comprises a
modified Fluid Solutions Model No. FSRO-600-10VS Reverse Osmosis
System (Fluid Solutions, Inc. Lowell, Mass.) having a nominal
design permeate flow rate of about 30-40 gal./min. The system, as
configured in the illustrated embodiment, is constructed from
food/pharmaceutical grade materials. The system may further
include, in some embodiments, a variety of additional valves,
switches, pressure gauges, transducers, temperature probes,
electronic/microprocessor-based monitoring/process control hardware
and software, etc., in addition to the particular components
illustrated, as would be apparent to those of ordinary skill in the
reverse osmosis/nanofiltration arts. System 500, as configured in
the illustrated embodiment, includes five filtration cartridges
502, 504, 506, 508, and 510. Cartridges 502, and 504 are arranged
in parallel and are connected in series with cartridges 506, 508
and 510, which are connected in series with each other. Parallel
cartridges 502 and 504 are fed by inlet manifold 512 connected to
cartridges 502 and 504 via lines 514 and 516 respectively.
Retentate output from cartridges 502 and 504 flows into outlet
manifold 518 via lines 520 and 522 respectively, and flows from
manifold 518 to cartridge 506 via line 524. Retentate output from
cartridge 506 is fed to cartridge 508 via line 526, and retentate
from cartridge 508 is fed to cartridge 510 via line 528. The
concentrated retentate, produced by final filtration cartridge 510
flows from the cartridge for collection or recycle via line 530.
Each of the filtration cartridges, 502, 504, 506, 508, and 510 as
illustrated, includes two FILMTEC.RTM. Model No. SW30-8040
spiral-wound filter membrane elements. The filter membrane elements
each include about 28 m.sup.2 of filter membrane area. The maximum
operating pressure for the filter membrane elements is about 1015
psi with a typical operating pressure of between about 600-900
psi.
[0078] As discussed previously, the inventive solvent reduction and
de-watering methods for forming concentrated consumable extracts,
for example coffee extracts, provide a variety of beneficial
features and advantages to the inventive extract producing methods
and systems. For example, in some embodiments involving the
production of coffee extracts, a de-watering process such as that
described above in reference to FIG. 6 can be used to concentrate
and de-water the coffee extracts produced by the inventive
extraction methods, previously described, to form even more highly
concentrated coffee extracts, for example containing at least about
6% wt. coffee solids, in some embodiments at least about 10% wt.
coffee solids, in some embodiments at least about 12% wt. coffee
solids, in some embodiments at least about 15% wt. coffee solids,
in some embodiments at least about 20% wt. coffee solids, in some
embodiments at least about 25% wt. coffee solids, in some
embodiments at least about 30% wt. coffee solids and in some
embodiments containing at least about 40% wt. coffee solids.
Furthermore, the highly concentrated extracts produced by the
inventive extraction and de-watering methods described herein can
advantageously retain an effective amount of the varietal flavor
and fragrance components of the roasted coffee from which they are
prepared. Such highly concentrated extracts can be advantageously
used for applications requiring low-water coffee flavoring
products. One such application involves the use of the inventive
highly concentrated coffee extracts as a flavoring ingredient for
the production of coffee ice cream, where excessive water can lead
to detrimental icing and texture degradation of the final ice cream
product. In addition, concentration and de-watering of coffee
extracts by the inventive concentration methods described herein
can advantageously provide concentrated coffee extract products
having a given quantity of coffee solids contained therein,
including an effective amount of varietal flavor and fragrance
components, which have a relatively low total product weight and
volume. For example, by increasing the concentration of an extract
by a factor of 2, for a given quantity of coffee fragrance and
flavor (proportional to the amount of coffee solids present) the
volume of a coffee extract product can similarly be reduced by a
factor of 2 and the weight of the product can be reduced by nearly
this amount, thus saving substantial shipping and packaging costs,
similarly for even higher levels of concentration able to be
obtained by practicing the current invention, for example increases
in concentration by a factor of 5, 10, 20, 30, 40, 50, or 60, even
greater reduction in shipping, packaging and storage costs can be
realized.
[0079] Also, as discussed above, the inventive extraction and
concentration methods allow for the formation of concentrated
coffee extracts having a variety of different fragrance and flavor
characteristics to be produced by extracting a given charge of
roasted coffee. The nature of the inventive extraction processes
described herein is that the less water that is used for a coffee
extraction, the higher will tend to be the concentration level of
coffee solids in the extract produced, but also, the more flavor
and extractable coffee solids will tend to be left behind in the
non-exhaustively extracted grinds remaining in the extractor. Using
the inventive concentration method, a first-pass, high
concentration coffee extract can be produced by extracting a fresh
charge of roasted coffee with a relatively small quantity of water
and set aside as an "extra virgin" coffee concentrate. The roasted
coffee in the extractor may then be subjected to one or more
additional extraction cycles utilizing an increased amount of water
during the extraction in order to more exhaustively extract the
roasted coffee and improve extraction efficiency. The extracts
obtained from these secondary and subsequent extraction cycles can
then be de-watered using the inventive concentration methods
described above to have, in some embodiments, an overall coffee
solids concentration similar to that of the "extra virgin"
concentrate. The "extra virgin" concentrate and the de-watered
concentrates produced from subsequent extraction cycles can then be
blended to form an extract having a balance of relatively sweet
flavor/fragrance attributes imparted by the "extra virgin" extract
and more bitter/acidic flavor/fragrance attributes imparted by the
extracts produced by secondary or subsequent extractions of the
roasted coffee. These blended extracts often have an overall
flavor/fragrance more typical of beverage quality coffee produced
by many prior art coffee beverage making methods. Such a combined
extract may then be used as a flavoring agent, or may be
reconstituted by dilution with water to a final dissolved coffee
solid concentration typical of a beverage strength extract, for
example containing between about 1% wt. dissolved coffee solids and
about 4% wt. coffee solids, to produce a flavorful and well
balanced coffee beverage therefrom. The particular balance between
sweetness and bitterness/acidity can be readily adjusted, as
desired, for example by adjusting the relative proportions of
"extra virgin" extract and extracts produced by subsequent
extraction and concentration in the blended extract. For
embodiments where the overall coffee solids concentration of the
"extra virgin" extracts and of the extracts produced by subsequent
extraction of the roasted coffee, followed by concentration of the
extract by de-watering, is about the same, where a richer, sweeter
extract/beverage is desired, the amount of the "extra virgin"
extract added to the blend should be greater than the amount of
extract produced by subsequent extraction and concentration, for
embodiments where a tarter, more bitter extract/beverage is
desired, the amount of the "extra virgin" extract added to the
blend should be less than the amount of extract produced by
subsequent extraction and concentration, and for embodiments where
a more evenly balanced extract/beverage is desired, the amount of
the "extra virgin" extract added to the blend should be about equal
to the amount of extract produced by subsequent extraction and
concentration.
[0080] In general, the inventive extraction and de-watering methods
provide a wide range of flexibility for producing "extra virgin"
extracts and other extracts produced by more thorough extraction of
a roasted coffee, each having a high level of concentration of
dissolved coffee solids, for example at least about 6% wt.
dissolved coffee solids, which may be combined in a variety of
proportions to produce extracts having customized flavor/fragrance
profiles, or which may be sold separately to different markets.
[0081] Alternatively, in other embodiments, a single charge of
roasted coffee can be exhaustively extracted in a single extraction
to produce a beverage strength or lower than beverage strength
extract having flavor characteristics typical of conventionally
brewed coffees, and this extract can subsequently be de-watered and
concentrated as described above to produce a concentrated extract
having reduced volume and weight, which can subsequently be
reconstituted with water to produce a coffee beverage having the
same flavor characteristics typical of conventionally brewed
coffees. Because the flavor, quality, and shelf-life of coffee
extracts can be reduced by prolonged exposure to oxygen, in
preferred embodiments of the invention, the exposure of the
extract, during extraction, de-watering, and any subsequent
handling, and packaging, to atmospheric air is minimized, for
example by utilizing inert gases, such as nitrogen, as
blanket/purge gases for contacting the extract during production
and processing, as described previously.
[0082] The function and advantage of the invention will be more
fully understood from the examples below. The following examples
are intended to illustrate the operation of the invention, but not
to exemplify the full scope of the invention.
EXAMPLE 1
One Pass Extraction Without Subsequent De-Watering
[0083] The industrial scale extractor described in connection with
FIGS. 1-4 was used to produce a coffee extract using the methods
described in the preceding sections with the modifications
indicated below. Approximately 265 lbs. of a blend of Costa Rican,
Colombian, and Sumatran coffee beans, roasted to a medium dark
finish, were ground using a Bunn coffee grinder (HVG, Bunn-o-matic,
Springfield, Ill.) on a setting of 4.0. A Rotap sieve analysis
indicated an 80% retention in Tyler sieves 12, 16, and 18, with the
remaining 20% distributed across sieves 20, 30, 40, 45, and the
bottom tray.
[0084] The vessel was filled with the dry ground coffee forming a
bed and the system was wetted with hot water, from a supply
maintained at 193 degrees F. and 90 psig, as described above. Valve
25 on the extract outlet line 23 was then closed and about 40
gallons of the hot water was added to the vessel via inlet line 46
yielding a final vessel pressure of about 90 psig. the vessel was
then "burped" to remove excess air as previously described and then
pressurized to about 120 psig with pressurized air. The coffee was
"pressure-treated" at this pressure without flow for about 10 min.,
at which time, valve 25 was opened to allow the extract to flow
from the vessel, through a stainless steel heat exchanger (chiller
28) operated to lower the temperature of the exiting extract from
about 165 degrees to about 55 degrees F. in approximately 2 min.,
and into a collection container. When the pressure in the vessel
dropped to about 90 psig, the hot water supply to the vessel was
reestablished by opening valve 47 on aqueous solvent inlet line 46.
An additional 90 gallons of hot water were then passed through the
bed of coffee before closing valve 47. When no more extract was
observed flowing from the vessel, pressurized air was supplied to
the vessel at 120 psig to purge residual extract from the bed for
collection. The total yield of extract was about 100 gallons from
the 265 lb of dry coffee.
[0085] The extract was judged by taste and smell testing to have
exceptional sweetness with a clear coffee flavor retaining the
varietal components, and substantially free of acidic off-flavors.
The extract had a Brix reading of about 8.0 (about 6.5% dissolved
solubles) and can be reconstituted with about 7 lbs. water per
pound of extract to yield a coffee beverage of normal drip brew
strength, but with superior sweetness and flavor.
EXAMPLE 2
Two Pass Extraction with Subsequent De-Watering of the Second-Pass
Extract and Formation of a Blended Coffee Extract
[0086] The industrial scale extractor described in connections with
FIGS. 1-4 was used to produce a coffee extract using the methods
described in the previous section with the modifications indicated
below. Approximately 200 lbs. of Sumatran coffee beans were roasted
and ground as described above in Example 1.
[0087] The extraction vessel was filled with the dry ground coffee
and about 60 gallons of a first-pass coffee extract was produced as
described previously for Example 1, except that in the present
example pressurized nitrogen was utilized in place of the
pressurized air in Example 1. Also, the step, in Example 1, of
passing additional hot water through the bed of coffee performed
immediately prior to the purging of residual extract from the bed
with gas was omitted in the present example. The total yield of the
first-pass extract was about 60 gallons from the 200 lbs. of dry
coffee. This extract was set aside.
[0088] A second-pass extract was prepared, as described above,
except using the same charge of ground coffee used previously for
producing the first-pass extract, and except that after extract was
collected from the vessel immediately subsequent to the pressure
treat step and before purging residual extract from the bed with
nitrogen, an additional of 60 gals. of hot water was passed through
the bed of coffee in a similar fashion as that described above in
Example 1. The total yield of second-pass extract was about 120
gals.
[0089] The second-pass extract was then de-watered using the PROSYS
Model No. 400 Series Reverse Osmosis System (configured with four
Model No. 4921S Koch nanofiltration membrane cartridges, arranged
in parallel) described above in the context of FIG. 6. The system
was operated in a multi-pass/recycle mode, as described above,
wherein the extract was pumped through the filter elements in a
cross-flow fashion, and the concentrated retentate was recycled to
the extract supply container. The system was operated in this
fashion until about 60 gals. of aqueous solvent was collected from
the system as permeate. The resulting concentrated extract was then
mixed in equal proportions with the first-pass extract produced
above to yield a blended, concentrated coffee extract.
[0090] The blended extract was judged by taste and smell testing to
have a clear coffee flavor that was well balanced with respect to
sweet and bitter/acidic flavor components. The extract also was
judged to retain the varietal components indicative of the Sumatran
roasted coffee from which it was prepared. The extract had a Brix
reading of about 8.0 (about 6.5% wt. dissolved solubles), and can
be reconstituted with about 7 lbs. water per pound of extract to
yield a coffee beverage of normal brew strength, and with
well-balanced coffee flavor including desirable varietal flavor and
fragrance components.
EXAMPLE 3
One Pass Extraction with Subsequent De-Watering to Produce a Highly
Concentrated Coffee Extract
[0091] An industrial scale extractor similar to that described in
connection with FIGS. 1-4, except having a dome-shaped upper plate
with a single, center-mounted raw material feed line and valve fed
by a mechanical auger feed system. The industrial extractor
utilized for the present example had an internal capacity of about
62.5 cubic feet, designed to extract about 1300 lbs. of ground,
roasted coffee. About 1300 lbs. of the ground coffee described in
example 2 was fed to the extractor, followed by closure of the
valve on the raw material feed line.
[0092] The vessel was filled with the dry ground coffee forming a
bed and the system was wetted with hot water, from a supply
maintained at 193 degrees F. and 90 psig, as described above,
except the first about 250 gallons of hot water added to the
extractor were added through the bottom screen via line 23 and
through tangential lines 42 and 55. At 250 gallons, the vent line
was closed, and an additional about 50 gallons of hot water was
added to the closed extractor via line 46 and water spray head 63,
raising the internal pressure of the extractor to about 40-50 psig.
The coffee was "pressure-treated" at this pressure without flow for
about 30 min., at which time, valve 25 was controllably opened to
allow the extract to flow from the vessel at a flow rate of about
6-8 gal./min., through a basket filter and stainless steel heat
exchanger (chiller 28), which cooled the extract to a temperature
of about 50 degrees F., and into a collection container. The hot
water supply to the vessel was then reestablished at a controlled
supply pressure of about 40 psig by opening valve 47 on aqueous
solvent inlet line 46 and pumping hot water to the extractor at the
above-mentioned pressure and at a controlled flow rate of about 6-8
gal./min., until an additional about 600 gallons of hot water were
passed through the bed of coffee, at which point the flow was
discontinued and valve 47 was closed. When no more extract was
observed flowing from the vessel, pressurized nitrogen was supplied
to the vessel to purge residual extract (about 100 gallons) from
the bed for collection. The total yield of extract was about 1000
gallons from the 1300 lbs. of dry coffee.
[0093] The 1000 gallons of the above extract was then de-watered
using the Fluid Solutions Model No. 10037 Reverse Osmosis System
(configured with 15 FILMTEC Model No. BW30-4040 reverse osmosis
membrane cartridges) described above in the context of FIG. 7. The
system was operated in a multi-pass/recycle mode, as described
above, wherein the extract was pumped through the filter elements
in a cross-flow fashion, and the concentrated retentate was
recycled to the extract supply container. The system was operated
in this fashion until about 850 gals. of aqueous solvent was
collected from the system as permeate.
[0094] The concentrated extract was judged by taste and smell
testing to have a clear coffee flavor that was well balanced with
respect to sweet and bitter/acidic flavor components. The extract
also was judged to retain the varietal components indicative of the
Sumatran roasted coffee from which it was prepared. The extract had
a Brix reading of about 30 (about 25% wt. dissolved solubles), and
can be reconstituted with about 30 lbs. water per pound of extract
to yield a coffee beverage of normal brew strength, and with
well-balanced coffee flavor including desirable varietal flavor and
fragrance components.
[0095] While the invention has been shown and described above with
reference to various embodiments and specific examples, it is to be
understood that the invention is not limited to the embodiments or
examples described and that the teachings of this invention may be
practiced by one skilled in the art in various additional ways and
for various additional purposes. Those skilled in the art would
readily appreciate that all parameters and configurations described
herein are meant to be exemplary and that actual parameters and
configurations will depend upon the specific application for which
the systems and methods of the present invention are used. Those
skilled in the art will recognize, or be able to ascertain using no
more than routine experimentation, many equivalents to the specific
embodiments of the invention described herein. It is, therefore, to
be understood that the foregoing embodiments are presented by way
of example only and that, within the scope of the appended claims
and equivalents thereto, the invention may be practiced otherwise
than as specifically described. The present invention is directed
to each individual feature, system, or method described herein. In
addition, any combination of two or more such features, systems, or
methods, provided that such features, systems, or methods are not
mutually inconsistent, is included within the scope of the present
invention.
* * * * *