U.S. patent application number 12/488591 was filed with the patent office on 2009-12-24 for process for making a shelf-stable milk based beverage concentrate.
Invention is credited to Charles E. Sizer.
Application Number | 20090317514 12/488591 |
Document ID | / |
Family ID | 41431545 |
Filed Date | 2009-12-24 |
United States Patent
Application |
20090317514 |
Kind Code |
A1 |
Sizer; Charles E. |
December 24, 2009 |
Process For Making A Shelf-Stable Milk Based Beverage
Concentrate
Abstract
A concentrate, system and low-temperature process for preparing
a shelf-stable milk concentrate that does not require ultra-high
temperature thermal processing for control of the microbiology of
the product is disclosed herein. The method preferably incorporates
aseptic technology and the enzymatic reduction of lactose to
control water activity. The method preferably includes the
enzymatic conversion of the lactose in the milk to its component
sugars glucose and galactose, which preferably changes the
colligative properties of the concentrate, decreases the amount of
free water, and reduces the osmolarity.
Inventors: |
Sizer; Charles E.;
(Westford, MA) |
Correspondence
Address: |
Clause Eight Intell. Prop. Service
P.O Box 131270
Carlsbad
CA
92013
US
|
Family ID: |
41431545 |
Appl. No.: |
12/488591 |
Filed: |
June 22, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61075015 |
Jun 24, 2008 |
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Current U.S.
Class: |
426/42 ;
99/454 |
Current CPC
Class: |
A23C 9/1206 20130101;
A23C 1/16 20130101; A23C 3/03 20130101; A23C 1/12 20130101; A23C
9/1307 20130101 |
Class at
Publication: |
426/42 ;
99/454 |
International
Class: |
A23C 1/16 20060101
A23C001/16; A23C 9/12 20060101 A23C009/12 |
Claims
1. A method for preparing a shelf-stable milk concentrate, the
method comprising: concentrating milk using low temperature, vacuum
evaporation to produce a milk concentrate; adding a lactase enzyme
and water to the milk concentrate to hydrolyze the milk concentrate
into a concentrate of glucose and galactose; and dissolving
anhydrous sugar into the concentrate of glucose and galactose to
form a shelf-stable milk concentrate with minimal water
activity.
2. A method for preparing a shelf-stable milk concentrate, the
method comprising: adding a lactase enzyme and water to a milk
concentrate to hydrolyze the milk concentrate into a hydrolyzed
milk concentrate comprising glucose and galactose, the hydrolyzed
milk concentrate having a minimal water activity.
3. The method according to claim wherein a minimal water activity
is less than 0.85.
4. The method according to claim 2 further comprising: adding a
milk powder to the hydrolyzed milk concentrate to create a second
milk concentrate having 4 times to 8 times concentration; adding
anhydrous sugar to the second milk concentrate with agitation and
shearing to create a first milk mixture, the anhydrous sugar added
in an amount ranging from 1 to 50 weight percent of the first milk
mixture; heating the first milk mixture to a temperature ranging
from 40.degree. C. to 80.degree. C.; holding the first milk mixture
until a water activity of the first milk mixture ranges from 0.8 to
0.9; adding at least one additional ingredient to the held first
milk mixture to create a second milk mixture; thermally treating
the second milk mixture to create a finished milk concentrate; and
packaging the finished milk concentrate.
5. The method according to claim 4 wherein the additional
ingredient comprises at least one of stabilizers, salt and
flavoring.
6. The method according to claim 4 wherein thermally treating the
second milk mixture comprises heating the second milk mixture to a
Pasteurization temperature ranging from 72.degree. C. to
125.degree. C.
7. The method according to claim 4 wherein the additional
ingredient comprises at least one of stabilizers, salt and
chocolate.
8. The method according to claim 2 further comprising: introducing
a milk product into a balance tank; heating the milk product in a
holding tube at a temperature ranging from 170.degree. F. to
240.degree. F. to create a heated milk product; introducing the
heated milk product into a pre-sterilized vacuum chamber as a
falling film to remove water from the heated milk product to create
a condensed milk product; and homogenizing the condensed milk
product in an aseptic homogenizer to create the milk
concentrate.
9. The method according to claim 2 further comprising: introducing
a raw milk product into a balance tank; heating the raw milk
product in a preheater to create a preheated milk product;
injecting the preheated milk product into a first effect wherein
the preheated milk product is heated at a temperature of about
70.degree. C. to evaporate water and increase a solids content of
the preheated milk product to create a first effect milk product
with a solids concentration of from 10% to 13%; injecting the first
effect milk product into a second effect wherein the first effect
milk product is heated at a temperature of about 65.degree. C. to
evaporate water and increase a solids content of the first effect
milk product to create a second effect milk product with a solids
concentration of from 13% to 18%; injecting the second effect milk
product into a third effect wherein the second effect milk product
is heated at a temperature of about 62.degree. C. to evaporate
water and increase a solids content of the second effect milk
product to create a third effect milk product with a solids
concentration of from 18% to 27%; injecting the third effect milk
product into a fourth effect wherein the third effect milk product
is heated at a temperature of about 60.degree. C. to evaporate
water and increase a solids content of the third effect milk
product to create the milk concentrate with a solids concentration
of from 28% to 34%; injecting the milk concentrate into a fifth
effect along with the a lactase enzyme, wherein the fifth effect is
heated at a temperature of about 48.degree. C. to evaporate water
and increase a solids content to create hydrolyzed milk concentrate
with a solid concentration of from 34% to 42%; injecting the
hydrolyzed milk concentrate into a sixth effect wherein the
hydrolyzed milk concentrate is heated at a temperature of about
43.degree. C. to evaporate water and increase a solids content of
hydrolyzed milk concentrate to create a final hydrolyzed milk
concentrate with a solids concentration of from 42% to 50%; holding
the final hydrolyzed milk concentrate in an aseptic tank at a
temperature of about 80.degree. F.; and packaging the final
hydrolyzed milk concentrate in an aseptic container using an
aseptic filling machine.
10. The method according to claim 9 wherein the raw milk product is
heated to a temperature of 100.degree. C. for a time period ranging
from 1 second to five minutes to inactive a plurality of
microorganisms and a plurality of enzymes.
11. The method according to claim 2 further comprising
reconstituting the hydrolyzed milk concentrate into a fresh-tasting
product.
12. The method according to claim 2 further comprising minimizing a
plurality of thermal reactions of the hydrolyzed milk concentrate
by incorporating a plurality of dry ingredients at an end of the
method and by chemically increasing the osmolality of the
hydrolyzed milk concentrate using the lactase enzyme.
13. A system for preparing a shelf-stable milk concentrate, the
system comprising: a source of a milk product; means for
concentrating the milk product using low temperature, vacuum
evaporation to produce a milk concentrate; and means for adding a
lactase enzyme and water to the milk concentrate to hydrolyze the
milk concentrate into a hydrolyzed milk concentrate comprising
glucose and galactose.
14. The system according to claim 13 further comprising means for
dissolving anhydrous sugar into the hydrolyzed milk concentrate to
form a shelf-stable milk concentrate with minimal water
activity.
15. The system according to claim 13 wherein the means for
concentrating the milk product comprises a plurality of
effects.
16. The system according to claim 13 wherein the means for
concentrating the milk product comprises an aseptic vacuum cooling
vessel.
17. The system according to claim 16 wherein the means for
concentrating the milk product further comprises an aseptic
homogenizer.
18. The system according to claim 14 further comprising means for
aseptically packaging the shelf-stable milk concentrate.
19. The system according to claim 14 wherein the shelf-stable milk
concentrate has a water activity value lower than 0.85.
20. The system according to claim 13 wherein the hydrolyzed milk
concentrate is from 70% to 99.5% hydrolyzed.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The Present Application claims priority to U.S. Provisional
Patent Application No. 61/075,015, filed on Jun. 24, 2008, which is
hereby incorporated by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to processes for making shelf
stable milk beverages.
[0005] 2. Description of the Related Art
[0006] For millennia man has tried unsuccessfully to devise a
method for preserving milk which would retain the nutrients and
qualities of fresh milk. Roman soldiers subsisted on rations made
from dried milk using primitive sun drying techniques. Later
technology developed by Gail Borden (1858) resulted in sweetened
condensed milk which could be preserved for years using simple
concentration methods utilizing water activity as the
microbiological control point. More modern milk processing and
packaging technologies combine Ultra-High Temperature Processing
with aseptic packaging to preserve the shelf-life of milk. The
foregoing technologies achieved the preservation aspects but failed
to preserve the fresh quality needed for ready to drink products.
Sweetened condensed milk is made by concentrating milk 2.5.times.
with added sucrose to control the water activity (.alpha.<0.85).
Water activity is a measure of food dryness.
.alpha..sub.w=p/p.sub.0, where .alpha..sub.w is water activity, p
is the vapor pressure of water in the substance, and p.sub.0 is the
vapor pressure of pure water at the same temperature. Water
activity as a value has no dimensions. Pure water has a water
activity of 1. The resulting product is tan in appearance, has a
distinct fat off-taste, coarse texture from lactose crystallization
and cannot be reconstituted to a single strength beverage.
Similarly, evaporated milk is a 2.1.times. concentrate which is
placed in a can and thermally treated to produce a commercially
sterile product (in compliance with 21 CFR113). The resulting milk
is tan in appearance and unacceptable when diluted to single
strength.
[0007] Fluid single-strength milk requires a thermal treatment to
control microbial growth, inactivate enzymes and stabilize the
milk. The Pasteurized Milk Ordinance requires specific
time-temperature combinations for the inactivation of infectious
pathogens such as Coxiell burnetti, Mycobacterium tuberculosis and
Salmonella spp. in refrigerated milk products. Shelf-stable, UHT
milk products require a thermal treatment which addresses not only
the infectious pathogens but also the toxin producing,
heat-resistant spore-formers like Clostridium botulinum or Bacillus
cereus. Typical processes for UHT milk require heating the milk to
286.degree. F. for 6 seconds (or the equivalent process). UHT milk
has a pronounced cooked taste and is not well accepted.
[0008] UHT/aseptic treatment of milk concentrates has been
demonstrated commercially but is technically very difficult due to
problems associated with the stability of the concentrated product.
Lactose precipitation results in a graininess of the product and
slows reconstitution. Hydrolysis of the milk sugar prior to UHT
treatment results in increased Maillard reaction browning with
noticeable changes in the color and flavor of the milk. Hydrolysis
prior to UHT also results in decreased shelf-life for the
product.
[0009] Hydrolysis of lactose prior to processing results in
significant increases in Maillard browning reaction products and
produces an unacceptable product. Dosing of lactase enzyme using
sterile filtration significantly reduces the browning and extends
the life of the product.
[0010] The prior art discloses ultra-high pasteurization of milk
such as disclosed in Reaves et al., U.S. Pat. No. 6,887,505, for
Ultra-High Temperature Pasteurized Milk Concentrate, Package,
Dispenser And Method Of Producing Same.
[0011] There is a need for a milk concentrate that upon rehydration
tastes fresh.
BRIEF SUMMARY OF THE INVENTION
[0012] The present invention is preferably a method for preserving
milk using a concentration method that incorporates aseptic
technology and the enzymatic reduction of lactose to control water
activity. The method includes the enzymatic conversion of the
lactose in the milk to its component sugars glucose and galactose.
This reaction changes the colligative properties of the
concentrate, decreases the amount of free water, and reduces the
osmolarity.
[0013] Milk (0.2-3.25% fat) is concentrated using low-temperature,
vacuum evaporation to produce a 3.0-4.2.times. concentrate. As the
concentration of the milk increases, so does the viscosity. At this
point, the addition of lactase enzyme at a rate of 0.01-5 ml per
liter results in very rapid decrease in the lactose concentration
resulting in significant changes in the colligative properties of
the concentrate. The viscosity decreases and the milks ability to
be further concentrated improves dramatically. Further
concentration can be accomplished by further treatment in
temperature controlled vacuum pans or by the addition of non-fat
dry milk solids using high shear.
[0014] The hydrolysis of lactose requires the incorporation of
equal moles of water and lactose to yield one mole each of glucose
and galactose. Neutral lactase enzyme (2600-4000 units per liter
(MaxiLact)) is injected into the milk concentrate to hydrolyze the
lactose sugar into glucose and galactose. Preferably, a minimum of
70% of the lactose must be hydrolyzed and the desired level is in
the 98% range. This process reduces water activity by decreasing
the amount of water and by increasing the number of moles of sugar
dissolved in the concentrate. Since lactose solubility is about
21.6%, a 4.times. concentration of milk is the practical limit of
concentration using conventional technology. Further concentration
results in graininess, crystallization and viscosity increases.
Furthermore, the insoluble lactose must be subtracted from the
water activity equation since it is no longer dissolved.
[0015] Anhydrous sugar(s) (75/25 w/w) are dissolved in the
evaporated milk to begin reducing the water activity. The mixture
is then heated to a temperature sufficient to inactivate vegetative
pathogens (160-260.degree. F.) and cooled using vacuum expansion in
an aseptic falling film evaporator. The vacuum expansion minimizes
the thermal effects of the process on the milk and simultaneously
decreases the water concentration by about 1% for every 10 degrees
F. of cooling. The product is further cooled to about
70-120.degree. F. in a tubular heat exchanger and placed in an
aseptic tank equipped with an agitator. Neutral lactase enzyme
(2600-4000 units per liter (MaxiLact)) is injected into the milk to
hydrolyze the lactose sugar into glucose and galactose. Preferably,
a minimum of 70% of the lactose must be hydrolyzed and the desired
level is in the 98% range.
[0016] The aseptic hydrolysis of lactose accomplishes many
purposes. The majority of humans in the world are lactose
intolerant. Hydrolysis of the lactose allows them to digest the
milk without suffering from gas and bloating. In addition to the
nutritional aspects, the hydrolysis reduces the water activity in
the product by increasing the molarity of the solutes by forming
two gram molecular weights of sugars from one. This essentially
doubles the osmolarity contribution of the milk component of the
formula which reduces the water activity for control of the
microorganisms. The hydrolysis of the lactose into glucose and
galactose uses one mole of H.sub.2O per mole weight of lactose
further reducing the water activity.
[0017] The thermal process addresses the health and safety aspects
of this product by inactivating vegetative pathogens which can
survive down to a water activity of 0.85. Toxin forming
sporeformers like C. botulinum are unable to grow at a water
activity of less than 0.93. The most resistant spore-forming toxin
form B. cereus bacteria are unable to grow at a water activity of
less than 0.915. Thus, the combination of concentration, thermal
treatment, enzymatic reduction of water activity and aseptic
processing-packaging results in a product which is
shelf-stable.
[0018] The typical application of this product would be for
confectionary use, un-refrigerated distribution of commodity milk,
production of whipped toppings, re-constitution of shakes, malts,
smoothies or for re-constitution as a single strength beverage.
[0019] The concentrate is not governed by the FDA under 21CFR113 or
21CFR108 and is thus exempt from the low-acid canned foods (LACF)
regulations. Similarly, condensed milk is not regulated by the
Pasteurized Milk Ordinance and is considered by the USDA to be a
Class II milk product.
[0020] A process for preparing a shelf-stable Pasteurized milk
concentrate which can be reconstituted to a fresh-tasting product
is disclosed herein. A low-temperature process for preparing a
shelf-stable milk concentrate that does not require ultra-high
temperature thermal processing for control of the microbiology of
the product is disclosed herein. A method for preserving milk
products which minimizes the thermal exposure of the protein
fractions to temperatures where they are denatured which minimizes
the thermal damage to the product is disclosed herein. A process
for reducing the water activity of the product enzymatically rather
than by thermal methods is disclosed herein. An enzymatic process
which changes the colligative properties of concentrated milk
making it possible to incorporate a higher concentration of solids
is disclosed herein. A method for minimizing the thermal reactions
of milk concentration by incorporating dry ingredients at the end
of the process and by chemically increasing the osmolality of the
product using lactase enzyme is disclosed herein. A method for
removing lactose sugar from milk beverages is disclosed herein. A
method for preserving a milk concentrate which can be reconstituted
and dispensed is disclosed herein. A process for enzymatically
removing sugars which promote product "graininess" is disclosed
herein. A method for preparing a commercially sterile product which
uses water activity to prevent the growth of spore-forming
pathogens and which utilizes thermal processing to address
vegetative spoilage organisms and pathogens is disclosed herein. A
method of enzymatically preserving a food product to make it
shelf-stable is disclosed herein. A method to control water
activity enzymatically is disclosed herein. A method to minimize
the browning of shelf-stable lactose reduced milk concentrates is
disclosed herein. A method for making a lactose-reduced milk
concentrate having active lactase enzyme is disclosed herein. A
method for making a lactose-reduced milk concentrate having active
lactase enzyme incorporating aseptic dosing of lactase enzyme into
the evaporator effect which maintains the optimum enzyme activity
is disclosed herein.
[0021] Having briefly described the present invention, the above
and further objects, features and advantages thereof will be
recognized by those skilled in the pertinent art from the following
detailed description of the invention when taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0022] FIG. 1 is a graph of the water activity of concentrated skim
milk and lactose reduced skim milk.
[0023] FIG. 2 is a block diagram of a system for a thermal process
incorporating a microbiological kill step, concentration step,
aseptic homogenization, aseptic dosing, an aseptic reaction vessel,
a cooler and aseptic packaging.
[0024] FIG. 3 is a graph of calculated water activity for
concentrated lactose reduced milk with different levels of
anhydrous fructose.
[0025] FIG. 4 is a block diagram of a system for an aseptic
multi-effect evaporator with aseptic filtered lactase enzyme
injection, a reactor vessel and aseptic packaging.
[0026] FIG. 5 is a graph of temperature (T) and dry matter content
(c) of skim milk as a function of time (t) for a multiple effect
evaporator illustrating the point of introduction of lactase enzyme
after effect 4 at a temperature of 46 degrees Centigrade.
DETAILED DESCRIPTION OF THE INVENTION
[0027] A process for preparing a shelf stable milk concentrate
which can be reconstituted into a fresh tasting product is
disclosed below.
[0028] The product is preferably made from conventional condensed
milk formulated with traditional amounts of stabilizers required to
maintain the suspension of milk proteins without precipitation.
Anhydrous sugars (sucrose, glucose or fructose) are preferably
incorporated (at 0-40% weight) into the pasteurized 4.times. milk
concentrate with agitation and shearing. The temperature during
this step is elevated to 40-80.degree. C. to aid in the
solublization of the sugars. The formed syrup is preferably free of
crystals to prevent future crystallization. The warm, sweetened
milk concentrate is preferably introduced at a pre-determined
temperature into a pre-sterilized vacuum chamber (500 mbar) to
decrease the temperature and evaporate additional water using
technology developed for UHT processing. The vacuum chamber is
preferably continuously evacuated using an aseptic pump to transfer
the material over to a sterile tank. Further cooling using
conventional aseptic tubular heat exchangers may be required to
reduce the temperature of the sweetened condensed milk to the
optimal temperature for lactose hydrolysis. The degree of
concentration is preferably regulated by the initial temperature of
the milk product as the milk product is introduced into the vacuum
chamber and the degree of vacuum in the chamber.
[0029] A sterile tank is preferably used for a mixing tank to
incorporate lactase enzyme into the milk. A solution of lactase
enzyme is sterile filtered using aseptic technology and transferred
into the sterile tank. The aseptic tank preferably has aseptic
agitation to thoroughly mix any components added to the tank. The
enzyme is a neutral lactase enzyme (2,600 to 4,000 lactase enzyme
units) at a concentration of between 0.1 and 0.0001%. The enzyme
acts in the following manner:
Lactose+water.fwdarw.glucose+galactose
[0030] The reaction preferably takes one mole of the disaccharide
lactose and creates two moles of the simple sugars glucose and
galactose. The reaction reduces the osmolarity of the condensed
milk by doubling the moles of sugar and by using one mole of water
for hydrolysis of the .alpha.-linkage between the sugar moieties.
The resulting product has received a thermal treatment adequate to
address infectious, vegetative pathogens and has a water activity
sufficiently low to prevent the growth of C. botulinum
(.alpha.<0.93) and B. cereus (.alpha.<0.915). The water
activity of the product is preferably 0.85 or below to address
spoilage microbes of concern. The product is preferably
commercially sterile.
[0031] Formulations for some preferred products are provided in
Tables One, Two and Three. Table One is for an unflavored milk
product. Table Two is for a vanilla flavored milk product and Table
Three is for a chocolate flavored milk product.
TABLE-US-00001 TABLE ONE Ingredient Weight % 4X concentrated
milk(3.25% fat ss, with 70.00% additives) Anhydrous Sugar (sucrose,
glucose or 29.99% fructose) Lactase enzyme .01%
[0032] Vanilla Milk
TABLE-US-00002 TABLE TWO Ingredient Weight % 3.75X concentrated
milk (2.0% fat ss, 79.754% with additives) Anhydrous Cane Sugar
20.00% Vanilla flavor (FONA KS06217wsi) .20% Salt .036% Lactase
enzyme .01%
[0033] Chocolate Milk
TABLE-US-00003 TABLE THREE Ingredient Weight % 4X Milk (3.25% fat
single strength) 69.00% Sugar 26.00% Cocoa powder 4.00% Vanilla
flavor (anhydrous, ethanol) .99% Lactase enzyme .01%
[0034] Mixing
[0035] The dry ingredients are preferably completely dissolved in a
warmed milk concentrate along with other ingredients including
flavors and stabilizers.
[0036] Processing The milk is preferably processed using a system
designed for UHT processing system that preheats the milk product
to 175.degree. F. using indirect heating and is capable of
injecting live steam into the product to bring it to a sterilizing
temperature in the range of 175.degree. F. -310.degree. F. The
system is preferably connected to an aseptic tank equipped with
agitation and a sterile filtration system. The sterile product is
preferably fed to an aseptic filler downstream of the sterile
tank.
[0037] The equipment is preferably first brought to a condition of
sterility by means of raising the temperature of the equipment to a
least 250.degree. F. for 30 minutes or the equivalent process. The
system preferably operates in a water production mode with the hold
tube at 280.degree. F. until the milk product is introduced into
the balance tank. As the milk product enters the system, the hold
tube temperature is preferably reduced so as to maintain the
integrity of the system and provide a minimal process for the
prevention of pathogens in the milk product. The temperature is
preferably brought down to the range of 170-240.degree. F. in the
holding tube. At the end of the holding tube, the milk concentrate
preferably exits through a pressure reduction valve entering a
pre-sterilized vacuum chamber. The concentrate preferably forms a
falling film which provides a maximum area for removal of water
from the product. The amount of water removed is dependent on the
initial temperature on introduction into the chamber and the vacuum
level maintained in the chamber. Typically, a vacuum of from7-30
inches of mercury is maintained in the vacuum vessel. The milk
product is preferably reduced in moisture by 1% for every
10.degree. F. of temperature decrease.
[0038] The final heating of the milk is preferably accomplished
with indirect heating such as plate heat exchangers or tubular heat
exchangers. Direct coupling of electrical energy with Ohmic
heating, direct heating or microwave accomplishes a rapid
temperature increase without the introduction of water.
[0039] The condensed milk is preferably removed from the vacuum
chamber using a positive pump such as a progressive cavity pump
made by Moyno. The milk is then preferably conveyed to an aseptic
homogenizer where it is homogenized at 2000/500 psi in two stage
aseptic homogenization. The condensed milk is preferably conveyed
to the final cooler where it is cooled to a temperature of less
than 100.degree. F. The milk is preferably conveyed to the aseptic
tank valve cluster for diversion into the aseptic tank.
[0040] An aseptic dosing unit, preferably having a filter pore size
of 0.2 microns, doses 0.1-0.0001% lactase enzyme into the milk
concentrate. The amount of enzyme incorporated is preferably
sufficient to quickly reduce the lactose concentration by at least
70% and most preferably by at least 97%. Other ingredients such as
salt (sodium chloride) can be simultaneously injected into the
product to reduce the water activity and minimize processing
equipment corrosion.
[0041] The lactose reduced milk is next packaged in a sterile
bag-in-box container to minimize water incorporation into the
product and to minimize the introduction of spoilage
microorganisms. The product preferably has a shelf-life of from 2
months to 12 months depending of the storage conditions.
[0042] FIG. 1 is graph of the water activity of concentrated skim
milk and lactose reduced skim milk showing data that the hydrolysis
of lactose can be used to reduce water activity. The addition of
lactase enzyme has a resultant decrease in water activity. The
results clearly demonstrate that water activity can be lowered by
enzymatic conversion of lactose to glucose and galactose. The drop
in water activity to 0.86 useful for preservation since bacterial
spores can grow down to a water activity of 0.915. FIG. 3 is graph
of calculated water activity for concentrated lactose reduced milk
with different levels of anhydrous fructose. The graph shows that a
milk concentrate with sucrose added decreases the water activity
(grams/100ml). By changing the sucrose to anhydrous fructose and
increasing the lactase enzyme, it is possible to get down to 0.71
preferably using a vacuum process. In an alternative embodiment,
additional lactase enzyme is added to get 100% hydrolysis of the
milk lactose. The formula is preferably underdosed by adding on a
volume basis rather than the moles of lactose basis. As can be seen
from the graph, lactose reduction decreases water activity to 0.87.
A vacuum removal of additional water is preferably used to decrease
water activity to below 0.85. 4-6% removal corresponds to a 40-60
degree temperature loss in the vacuum chamber. Lactase enzyme is
aseptically introduced into the product after cooling. Enzyme
hydrolysis provides a lowered water activity for a milk
concentrate.
[0043] Vanilla Milk Formula and Treatment.
[0044] A vanilla milk product is made from conventional condensed
milk (3.6-4.2.times. Grassland, Class II Condensed). Lactase enzyme
at 0.1-1 ml per liter is immediately added to the concentrate and
allowed to react until the lactose is 70-99.5% hydrolyzed. After
hydrolysis, milk powder (NFDM, Meijers) is added at a level to
bring the milk to the desired level of concentration. The milk can
be 4.times.-8.times. concentration as desired. The product is
formulated with much lower levels of the traditional amounts of
stabilizers required to maintain the suspension of milk proteins
without precipitation. Anhydrous sugars (sucrose, glucose or
fructose) are incorporated (at 0-50% weight (baker's percent)) into
the pasteurized 4-8.times. milk concentrate with agitation and
shearing. The temperature during this step will need to be elevated
to 40-80.degree. C. to aid in the solublization of the sugars and
yet not reduce the lactase enzyme activity. After incorporation of
the sugars, the mixture is held until the desired water activity is
reached (0.9-0.80). Additional ingredients such as stabilizers
(gums, CMC or emulsifiers), salt and flavor may be added at this
time. The water activity of each ingredient must be less than 0.85
to minimize adding more water. The formula for a five times
concentrate vanilla milk product is set forth in Table Four and a
formula for a six times concentrate vanilla milk product is set
forth in Table Five.
TABLE-US-00004 TABLE FOUR Ingredient Value Grassland Concentrate
1000 Fructose (anhydrous) 350 NFDM 112 Flavor 25 Salt 2.5
TABLE-US-00005 TABLE FIVE Ingredient Value Grassland Concentrate
1000 Fructose (anhydrous) 420 NFDM 208 Flavor 30 Salt 3
[0045] The mixture is then preferably thermally treated with a
process sufficient to inactivate the vegetative pathogenic
organisms. Spoilage organisms capable of growing in the product
under reduced must also be addressed by the final thermal process.
The thermal treatment of the lactose reduced milk concentrate is
preferably accomplished either by using aseptic processing and
packaging or by using hot-filling. The aseptic process uses a
presterilized aseptic processing system brought to the condition of
commercial sterility by the application of heat. As soon as the
system is sterilized, the milk product is preferably cooled
maintaining the hold tube temperature and positive pressure. The
milk product is preferably introduced and is used to push the water
out of the system. The interface of water and product results in a
mixture which has a water activity greater than the required limit.
This interfacial product must be completely pushed through the
system to prevent microbiological growth. As soon as the dissolved
solids or water activity limits are reached, the milk product is
packaged aseptically.
[0046] Alternatively, the milk product is heated to Pasteurization
temperature (72-125.degree. C.) and then hot-filled into a can,
bottle or plastic container. The container is immediately closed
and then cooled to ambient.
[0047] The processing step is preferably used as a final step to
reduce the water content. After delivering the thermal treatment
required for commercial sterility, the hot, lactose reduced milk
concentrate is introduced at a pre-determined temperature into a
pre-sterilized vacuum chamber (1-30 inches mercury vacuum) to
decrease the temperature and evaporate additional water using
aseptic originally technology developed for UHT processing. The
vacuum chamber is preferably continuously evacuated using an
aseptic pump to transfer the material over to a sterile tank.
Further cooling using conventional aseptic tubular heat exchangers
may be required to reduce the temperature of the sweetened
condensed milk to the optimal temperature for lactose hydrolysis.
The degree of concentration is preferably regulated by the initial
temperature of the milk as it is introduced into the vacuum chamber
and the degree of vacuum in the chamber. If additional enzyme is
required, the additional enzyme is introduced at this point prior
to the aseptic tank.
[0048] The sterile, aseptic tank is preferably used for a mixing
tank to incorporate lactase enzyme into the milk. A solution of
lactase enzyme is sterile filtered using aseptic technology and
transferred into the sterile tank. The aseptic tank preferably has
aseptic agitation to thoroughly mix any components added to the
tank. The enzyme is a neutral lactase enzyme (2,600 to 4,000
lactase enzyme units) at a concentration of between 0.1 and
0.0001%. The enzyme acts in the following manner:
Lactose+water.fwdarw.glucose+galactose
[0049] The reaction preferably takes one mole of the disaccharide
lactose and creates two moles of the simple sugars glucose and
galactose. The reaction preferably reduces the osmolarity of the
condensed milk by doubling the moles of sugar and by using one mole
of water for hydrolysis of the .alpha.-linkage between the sugar
moieties. The resulting product preferably has received a thermal
treatment adequate to address infectious, vegetative pathogens and
has a water activity sufficiently low to prevent the growth of C.
botulinum (.alpha.<0.93) and B. cereus (.alpha.<0.915). The
water activity of the product is preferably 0.85 or below to
address spoilage microbes of concern. The product is preferably
commercially sterile.
[0050] The addition of sugars for sweetening also reduces the water
activity. Monosaccharide sugars like fructose, glucose and
galactose have twice the water activity reducing power as
disaccharides like glucose or galactose. Typically, flavored milks
have between 5-8% sugar (single strength) added to increase the
sweetness. Fructose or glucose is/are preferably used alone or in
combination to sweeten and reduce water activity. FIG. 3 shows the
calculated water activity of lactose reduced milk (95% reduced)
concentrates with varying levels of monosaccharide.
TABLE-US-00006 TABLE SIX Ingredient Value Grassland Concentrate
1000 Fructose (anhydrous) 420 NFDM 208 Bakers Chocolate 120 Salt
3
[0051] A formula for chocolate milk is set forth in Table Six. The
chocolate milk is made in the same fashion as the vanilla milk with
the exception of the addition of the baker's chocolate. The
chocolate is melted and incorporated into the lactose reduced milk
concentrate with high shear. The lactose reduced milk concentrate
is preferably then homogenized to fully incorporate the chocolate
into a stable emulsion capable of extended storage. Emulsifiers and
stabilizers may be added to enhance stability. The chocolate milk
is preferably then thermally treated and packaged aseptically or
hot-filled. Chocolate withstands the hot-fill process since color
changes are not apparent after hot-filling.
[0052] Processing System for Processing Milk with Incorporated Dry
Milk Solids.
[0053] A processing system 40 for processing a milk product is
shown in FIG. 2. The equipment is preferably first brought to a
condition of sterility by means of raising the temperature of the
equipment to a least 250.degree. F. for 30 minutes or the
equivalent process. The system 40 operates in water production with
the hold tube at 280.degree. F. until a milk product is introduced
into a balance tank 51. As the milk product enters the system 40, a
temperature of a hold tube 54 is reduced so as to maintain the
integrity of the system 40 and provide a minimal process for the
prevention of pathogens in the milk product. The components of the
system 40 are in flow communication through aseptic tubing 50. The
temperature can be brought down to the range of 170-240.degree. F.
in the holding tube 54. At the end of the hold tube 54, the milk
product exits through a pressure reduction valve entering a
pre-sterilized vacuum vessel 55. The milk product preferably forms
a falling film which provides maximum area for removal of water
from the milk product. The amount of water removed is dependent on
the initial temperature on introduction into the chamber and the
vacuum level maintained in the chamber. Typically, a vacuum of from
7-30'' of mercury is maintained in the vacuum vessel 55. The milk
product is preferably reduced in moisture by 1% for every
10.degree. F. of temperature decrease. The final heating of the
milk is accomplished with indirect heating such as plate heat
exchangers or tubular heat exchangers. Although steam injection
(provided by an optional steam injector 53) is commonly used for
milk products, preferably in this system 40 a steam injector is not
utilized to avoid the introduction of additional water which must
be subsequently removed. Alternatively, direct coupling of
electrical energy with Ohmic heating, direct heating or microwave
accomplishes a rapid temperature increase without the introduction
of additional water into the milk product.
[0054] A condensed milk is removed from the vacuum vessel 55,
preferably using a centrifugal or positive pump such as a
progressive cavity pump made by Moyno. The condensed milk is
conveyed to an aseptic homogenizer 56 where the condensed milk is
homogenized, preferably at 2000/500 psi in a two stage aseptic
homogenization. The homogenized condensed milk is preferably
conveyed to a cooler where the homogenized condensed milk is
preferably cooled to a temperature of less than 100.degree. F. The
cooled, homogenized condensed milk is preferably conveyed to an
aseptic tank valve cluster for diversion into an aseptic reactor
tank 59.
[0055] An aseptic dosing unit 58, preferably having a filter pore
size of 0.2 microns, doses 0.1-0.0001% lactase enzyme from a
balance tank 57 into the aseptic reactor tank 59 having the cooled,
homogenized condensed milk to create a lactose reduced milk
product. The amount of enzyme incorporated is preferably sufficient
to quickly reduce the lactose concentration by at least 70% and
most preferably by at least 97%. Other ingredients such as salt
(sodium chloride) are simultaneously injected into the aseptic
reactor tank 59 to preferably reduce the water activity and
minimize processing equipment corrosion.
[0056] The lactose reduced milk product is preferably next cooled
at a cooler 60, and packaged, using an aseptic filling machine 61,
in a sterile bag-in-box container 65 to minimize water
incorporation into the product and to minimize the introduction of
spoilage microorganisms. The product preferably has a shelf-life of
from 2 months to 12 months depending on the storage conditions.
Since the microbiology is water activity controlled, there is no
need of micro testing to assure the commercial sterility of the
product and thus the final product can be immediately released for
distribution.
[0057] Processing System for Making a High-Solids, Liquid, Lactose
Reduced, Milk Concentrate.
[0058] Multi-effect effect evaporators are preferably used to
remove water from milk to make milk concentrates. A typical
evaporator uses 6-effects for sequential water removal. One such
multi-effect evaporator is an ANHYDRO Evaporation System available
from Anhydro A/S of Copenhagen, Denmark (see www.anhydro.com). Each
successive step operates at a lower pressure and subsequently at a
lower temperature as well.
[0059] FIG. 4 is a block diagram of a system 100 for an aseptic
multi-effect evaporator with aseptic filtered lactase enzyme
injection, a reactor vessel and aseptic packaging.
[0060] At the first effect 103a, raw milk in a single strength
balance tank 101 is heated with an indirect heater 102 to
100.degree. C. for 0.0001-5 minutes to inactivate target
microorganisms and inactivate enzymes. After the hold time, it is
injected into the first effect where water is flashed off rapidly
reducing the temperature as the moisture is removed. The typical
temperature profile for the milk undergoing the evaporation process
is illustrated FIG. 5. As the milk resides in the pan of the first
effect, additional heat is added to provide the energy to evaporate
the water. The temperature of the first effect is about 70.degree.
C. The solids content increases from 10% to 13% in the first
effect.
[0061] At the second effect 103b, the milk is pumped from the first
effect into the second effect which is maintained at a slightly
lower pressure. The pressure in the second effect also dictates the
temperature which is usually about 5.degree. C. lower than the
first effect. The milk solids increase from 13 to 18% as water is
removed.
[0062] At the third effect 103c, the milk is pumped from the second
effect into the third effect which is maintained at a slightly
lower temperature about 3.degree. C. lower than the previous
effect. The solids content increases from 18% to 27%.
[0063] At the third effect 103d, the milk is pumped from third
effect into the fourth effect which is maintained at a slightly
lower pressure about 2.degree. C. than effect three. Effect 4 is at
60.degree. C. This temperature is a legal pasteurization
temperature but also can reduce the activity of lactase enzyme. The
solids content increase from 28% to 34% in this effect.
[0064] At the fifth effect 107a, the milk from effect 4 is pumped
into the vacuum vessel of effect 5 at a temperature of 60.degree.
C. At this point, while the milk is at 60.degree. C., the lactase
enzyme is introduced into the milk. As the enzyme is added, it is
simultaneously flashed into fifth effect 107a reducing the
temperature to 48.degree. C. Lactase enzyme has its highest
activity at 47.degree. C. and thus this is the optimum location for
introduction of the enzyme. The security of the dosing valve is
maintained by the temperature and the activity of the enzyme is
optimal. As the enzyme resides in the pan of fifth effect 107a, the
enzyme rapidly hydrolyzes the lactose and changes the colligative
properties making it easier to handle by reducing viscosity. The
solids content of the concentrate increase from 34% to 42% as water
is evaporated. Additional water is used from the hydrolysis
reaction further increasing the solids content.
[0065] At the sixth effect 107b, the milk from fifth effect 107a is
pumped into the final vacuum vessel of the sixth effect 107b which
is at a temperature of 43.degree. C. Additional water is removed in
this section increasing the solids concentration from 42% to 50%.
Enzyme added in the fifth effect 107a remains active in this effect
and all subsequent process. The milk from sixth effect 107b is a
1+4 concentrate or a 5.times. milk. Further concentration can be
achieved on the same equipment by increasing the residence time and
increasing temperatures to accomplish a higher reduction. The
product is then pumped to aseptic tank 108 and stored at 80.degree.
F. Then the product is preferably pumped to aseptic filling machine
109 for packaging into an aspectic container 120.
[0066] Table Seven set forth the contents of an example pre and
post hydrolysis to a 7.2 times concentration.
TABLE-US-00007 TABLE SEVEN Post-hydrolyzation and Proximates
Pre-hydrolyzation 7.2 X conc. Water (g) 90.84 34.08 Energy (kcal)
34 Energy (kj) 143 Protein (g) 3.37 3.37 Total lipid (fat) (g) 0.08
0.08 Ash (g) 0.75 0.75 Glucose (g) 0 2.4175 Fructose (g) 0 Lactose
(g) 5.09 0.2545 Galactose (g) 0 2.4175 Water activity 0.99 0.85
[0067] From the foregoing it is believed that those skilled in the
pertinent art will recognize the meritorious advancement of this
invention and will readily understand that while the present
invention has been described in association with a preferred
embodiment thereof, and other embodiments illustrated in the
accompanying drawings, numerous changes modification and
substitutions of equivalents may be made therein without departing
from the spirit and scope of this invention which is intended to be
unlimited by the foregoing except as may appear in the following
appended claim. Therefore, the embodiments of the invention in
which an exclusive property or privilege is claimed are defined in
the following appended claims.
* * * * *
References