U.S. patent application number 09/963360 was filed with the patent office on 2002-04-11 for desiccation apparatus and method.
Invention is credited to Ware, Gerald J..
Application Number | 20020040643 09/963360 |
Document ID | / |
Family ID | 26928551 |
Filed Date | 2002-04-11 |
United States Patent
Application |
20020040643 |
Kind Code |
A1 |
Ware, Gerald J. |
April 11, 2002 |
Desiccation apparatus and method
Abstract
A desiccating device and method providing variable drying
conditions allowing the desiccated material to substantially
maintain its natural characteristics upon rehydration as well as
have a low microbial content. The method provides a process of
subjecting the material to ultrasound and flowing hot air or gas
for a defined period of time. The ultrasonic frequency,
temperature, air flow and time of exposure can be varied to produce
the most efficient drying conditions depending on the material to
be dried. The apparatus has plurality of drying chambers with
forced heated air or gas input and output ducts and ultrasonic
emitter. The material passes through each chamber at a
pre-determined rate on a perforated conveyor belt in one embodiment
of the invention. Optionally, the material may be placed on a
drying bed or substrate comprising a number of spheres.
Inventors: |
Ware, Gerald J.; (Vacaville,
CA) |
Correspondence
Address: |
John P. O'Banion
O'BANION & RITCHEY LLP
Suite 1550
400 Capitol Mall
Sacramento
CA
95814
US
|
Family ID: |
26928551 |
Appl. No.: |
09/963360 |
Filed: |
September 24, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60235066 |
Sep 25, 2000 |
|
|
|
Current U.S.
Class: |
99/467 ; 99/451;
99/483 |
Current CPC
Class: |
A23L 3/3418 20130101;
A23L 3/30 20130101; A23L 3/40 20130101; A23L 3/50 20130101; A23L
3/54 20130101; A23B 7/0205 20130101 |
Class at
Publication: |
99/467 ; 99/483;
99/451 |
International
Class: |
A23C 003/07; A23C
003/02 |
Claims
What is claimed is:
1. A method for producing dried foods, comprising: circulating a
heated gas around said food product until said food product has a
moisture content within the range of approximately zero to five
percent.
2. A method as recited in claim 1, further comprising
simultaneously exposing said food product to ultrasonic waves and
circulating said heated gas around said food product.
3. A method as recited in claim 2, wherein said food product is
exposed to ultrasonic wavelengths within the range of approximately
20 KHz to approximately 100 KHz for approximately fifteen to ninety
minutes.
4. A method as recited in claim 1, said method further comprising
placing said food product on a support substrate.
5. A method as recited in claim 1, wherein said circulated heated
gas comprises nitrogen.
6. A method as recited in claim 2, further comprising exposing said
food product to a second ultrasonic frequency and circulating
heated gas at a second temperature for a second period of time.
7. A method as recited in claim 6, further comprising exposing said
food product to a third ultrasonic frequency and circulating heated
gas at a third temperature for a third period of time.
8. A method for producing dried foods, comprising: exposing a food
product to ultrasonic waves; and circulating a heated gas around
said food product until said food product has a moisture content
within the range of approximately zero to five percent.
9. A method as recited in claim 8, wherein said steps of exposing
said food product to ultrasonic waves and circulating a heated gas
around said food product are performed simultaneously.
10. A method as recited in claim 8, wherein said food product is
exposed to ultrasonic wavelengths within the range of approximately
20 KHz to approximately 100 KHz for approximately fifteen to ninety
minutes.
11. A method as recited in claim 8, said method further comprising
placing said food product on a support substrate.
12. A method as recited in claim 8, wherein said circulated heated
gas is nitrogen.
13. A method as recited in claim 8, further comprising exposing
said food product to a second ultrasonic frequency and circulating
heated gas at a second temperature for a second period of time.
14. A method as recited in claim 13, further comprising exposing
said food product to a third ultrasonic frequency and circulating
heated gas at a third temperature for a third period of time.
15. A process for desiccating a material containing moisture,
comprising: placing said material onto a supporting substrate;
exposing said object to sound waves having a first ultrasonic
wavelength for a first period of time; simultaneously circulating a
heated gas at a first temperature around said material for said
first period of time; exposing said prepared and sized material to
sound waves having a second ultrasonic wavelength for a second
period of time; simultaneously circulating a heated gas at a second
temperature around said material for said second period of time;
exposing said prepared and sized material to sound waves having a
third ultrasonic wavelength for said third period of time;
simultaneously circulating a heated gas at a third temperature
around said material for third period of time; and separating said
material from said substrate.
16. A method of desiccating a material containing moisture
according to claim 15, wherein said heated gas is circulated around
said material and said support substrate at a rate between
approximately 150 cubic feet per minute per square foot and
approximately 450 cubic feet per minute per square foot.
17. A method of desiccating vegetables, comprising: preparing and
sizing the vegetables and placing the vegetables on a support
substrate; subjecting said vegetables to ultrasonic waves;
circulating air heated to a temperature of approximately
190.degree. F. to approximately 210.degree. F. around the
vegetables for approximately fifteen minutes; circulating heated
air at a temperature of approximately 170.degree. F. to
approximately 190.degree. F. around the vegetables for
approximately 15 minutes; circulating heated air at a temperature
of approximately 150.degree. F. to approximately 170.degree. F.
around the vegetables for about one hour until said vegetables have
a moisture content of approximately 5%; and removing the dehydrated
vegetables from said support substrate.
18. A method of desiccating vegetables according to claim 17,
wherein said heated air is circulated around said vegetables and
said support substrate at a rate between approximately 150 cubic
feet per minute per square foot and approximately 450 cubic feet
per minute per square foot.
19. An apparatus for producing dried foods, comprising: a housing
having a drying chamber; and means for circulating a heated gas
around said food product until said food product has a moisture
content within the range of approximately zero to five percent.
20. An apparatus as recited in claim 12, further comprising means
for exposing said food product to ultrasonic waves.
21. An apparatus as recited in claim 20, wherein said means for
circulating a heated gas around said food product and said means
for exposing said food product to ultrasonic waves are configured
to simultaneously expose said food product to said ultrasonic waves
and said heated gas.
22. An apparatus as recited in claim 20, wherein said means for
exposing said food product to ultrasonic waves is configured for
exposure at wavelengths within the range of approximately 20 KHz to
approximately 100 KHz for approximately fifteen to ninety
minutes.
23. An apparatus as recited in claim 19, further comprising a
support substrate configured for carrying said food product.
24. An apparatus as recited in claim 19, wherein said circulated
heated gas comprises nitrogen.
25. An apparatus for producing dried foods, comprising: a housing
having a drying chamber; means for exposing a food product to
ultrasonic waves; and means for circulating a heated gas around
said food product until said food product has a moisture content
within the range of approximately zero to five percent.
26. An apparatus as recited in claim 25, wherein said means for
circulating a heated gas around said food product and said means
for exposing said food product to ultrasonic waves are configured
to simultaneously expose said food product to said ultrasonic waves
and said heated gas.
27. An apparatus as recited in claim 25, wherein said means for
exposing said food product to ultrasonic waves is configured for
exposure at wavelengths within the range of approximately 20 KHz to
approximately 100 KHz for approximately fifteen to ninety
minutes.
28. An apparatus as recited in claim 25, further comprising a
support substrate configured for carrying said food product.
29. An apparatus as recited in claim 25, wherein said circulated
heated gas comprises nitrogen.
30. An apparatus for reducing the moisture content in a food
product, comprising: a housing; said housing having a first drying
zone and a second drying zone; a conveyor; said conveyor configured
to move said food product through said first and second drying
zones; a first heat source; said first heat source configured to
circulate heated gas through said first drying zone at a first
temperature; and a second heat source; said second heat source
configured to circulate heated gas through said second drying zone
at a second temperature.
31. An apparatus as recited in claim 30, further comprising: an
ultrasound source; said ultrasound source configured to expose said
food product in at least one of said drying zones to ultrasonic
waves.
32. An apparatus as recited in claim 30: wherein said first heat
source is configured to circulate said gas through said housing at
a rate of between approximately 150 cubic feet per minute per
square foot and approximately 450 cubic feet per minute per square
foot; and wherein said second heat source are configured to
circulate said gas through said housing at a rate of between
approximately 150 cubic feet per minute per square foot and
approximately 450 cubic feet per minute per square foot.
33. An apparatus as recited in claim 30: wherein said first heat
source is configured to circulate gas through said first drying
zone at a rate of rate of between approximately 150 cubic feet per
minute per square foot and approximately 450 cubic feet per minute
per square foot; and wherein said second heat source is configured
to circulate gas through said second drying zone at a rate of rate
of between approximately 150 cubic feet per minute per square foot
and approximately 450 cubic feet per minute per square foot.
34. An apparatus as recited in claim 30, further comprising: a
support substrate; said support substrate configured to carry said
food product.
35. An apparatus as recited in claim 34, wherein said support
substrate comprises a plurality of spheres.
36. An apparatus as recited in claim 35, wherein said conveyor
includes a plurality of vanes having an intermediate area
containing said spheres.
37. An apparatus as recited in claim 35, wherein said spheres are
held in a container placed on said conveyor.
38. An apparatus as recited in claim 31, wherein said ultrasonic
source and at least one said heat source are configured to
simultaneously expose said food product to said ultrasonic waves
and said heated gas.
39. An apparatus as recited in claim 38, wherein said ultrasonic
source is configured for exposure at wavelengths within the range
of approximately 20 KHz to approximately 100 KHz for approximately
fifteen to ninety minutes.
40. An apparatus for reducing the moisture content in a food
product, comprising: a housing; said housing having a first drying
zone and a second drying zone; a conveyor; said conveyor configured
to move said food product through said first and second drying
zones; a first heat source; said first heat source configured to
circulate heated gas through said first drying zone at a first
temperature; a second heat source; said second heat source
configured to circulate heated gas through said second drying zone
at a second temperature; and an ultrasound source; said ultrasound
source configured to expose said food product in at least one of
said drying zones to ultrasonic waves.
41. An apparatus as recited in claim 40: wherein said first heat
source is configured to circulate said gas through said housing at
a rate of between approximately 150 cubic feet per minute per
square foot and approximately 450 cubic feet per minute per square
foot; and wherein said second heat source are configured to
circulate said gas through said housing at a rate of between
approximately 150 cubic feet per minute per square foot and
approximately 450 cubic feet per minute per square foot.
42. An apparatus as recited in claim 40: wherein said first heat
source is configured to circulate gas through said first drying
zone at a rate of rate of between approximately 150 cubic feet per
minute per square foot and approximately 450 cubic feet per minute
per square foot; and wherein said second heat source circulates gas
through said second drying zone at a rate of rate of between
approximately 150 cubic feet per minute per square foot and
approximately 450 cubic feet per minute per square foot.
43. An apparatus as recited in claim 40, further comprising: a
support substrate; said support substrate configured to carry said
food product.
44. An apparatus as recited in claim 43, wherein said support
substrate comprises a plurality of spheres.
45. An apparatus as recited in claim 44, wherein said conveyor
includes a plurality of vanes having an intermediate area
containing said spheres.
46. An apparatus as recited in claim 44, wherein said spheres are
held in a container placed on said conveyor.
47. An apparatus as recited in claim 40, wherein said ultrasonic
source and at least one said heat source are configured to
simultaneously expose said food product to said ultrasonic waves
and said heated gas.
48. An apparatus as recited in claim 47, wherein said ultrasonic
source is configured for exposure at wavelengths within the range
of approximately 20 KHz to approximately 100 KHz for approximately
fifteen to ninety minutes.
49. An apparatus for reducing the moisture content in a food
product, comprising: a housing; said housing having first, second
and third drying zones; a conveyor; said conveyor configured to
move said food product through said drying zones; a first heat
source; said first heat source configured to circulate heated gas
through said first drying zone at a first temperature; a second
heat source; said second heat source configured to circulate heated
gas through said second drying zone at a second temperature; a
third heat source; said third heat source configured to circulate
heated gas through said third drying zone at a third temperature;
and an ultrasound source; said ultrasound source configured to
expose said food product in at least one of said drying zones to
ultrasonic waves.
50. An apparatus as recited in claim 49: wherein said first, second
and third heat sources are configured to circulate said gas through
said housing at a rate of between approximately 150 cubic feet per
minute per square foot and approximately 450 cubic feet per minute
per square foot.
51. An apparatus as recited in claim 49: wherein said first heat
source is configured to circulate gas through said first drying
zone at a rate of rate of between approximately 150 cubic feet per
minute per square foot and approximately 450 cubic feet per minute
per square foot; wherein said second heat source is configured to
circulate gas through said second drying zone at a rate of rate of
between approximately 150 cubic feet per minute per square foot and
approximately 450 cubic feet per minute square foot; and wherein
said third heat source is configured to circulate gas through said
third drying zone at a rate of rate of between approximately 150
cubic feet per minute per square foot and approximately 450 cubic
feet per minute per square foot.
52. An apparatus as recited in claim 49, further comprising: a
support substrate; said support substrate configured to carry said
food product.
53. An apparatus as recited in claim 52, wherein said support
substrate comprises a plurality of spheres.
54. An apparatus as recited in claim 53, wherein said conveyor
includes a plurality of vanes having an intermediate area
containing said spheres.
55. An apparatus as recited in claim 53, wherein said spheres are
held in a container placed on said conveyor.
56. An apparatus as recited in claim 49, wherein said ultrasonic
source and at least one said heat source are configured to
simultaneously expose said food product to said ultrasonic waves
and said heated gas.
57. An apparatus as recited in claim 56, wherein said ultrasonic
source is configured for exposure at wavelengths within the range
of approximately 20 KHZ to approximately 100 KHz for approximately
fifteen to ninety minutes.
58. An apparatus for reducing the moisture content in food
material, comprising: a housing; said housing having at least one
drying chamber; means for exposing said food material to sound
waves having a first ultrasonic wavelength for a first period of
time and simultaneously circulating a heated gas at a first
temperature around said material for said first period of time;
means for exposing said food material to sound waves having a
second ultrasonic wavelength for a second period of time and
simultaneously circulating a heated gas at a second temperature
around said material for said second period of time; means for
exposing said food material to sound waves having a third
ultrasonic wavelength for said third period of time and
simultaneously circulating a heated gas at a third temperature
around said material for third period of time; and means for
separating said material from said substrate.
59. An apparatus for desiccating a food product, comprising: an
ultrasound source; said ultrasound source configured to subject a
food product to ultrasonic waves; a first source of air heated to a
temperature of approximately 190.degree. F. to approximately
210.degree. F. and configured to circulate heated air around the
food product for approximately fifteen minutes; a second source of
air heated to a temperature of approximately 170.degree. F. to
approximately 190.degree. F. and configured to circulate heated air
around the food product for approximately fifteen minutes; and a
third source of air heated to a temperature of approximately
150.degree. F. to approximately 170.degree. F. and configured to
circulate heated air around the vegetables for approximately one
hour.
60. An apparatus as recited in claim 59, wherein said first, second
and third sources of heated air are configured to said head air
through said housing at a rate of between approximately 150 cubic
feet per minute per square foot and approximately 450 cubic feet
per minute per square foot.
61. An apparatus as recited in claim 59: wherein said first source
or air is configured to circulate heated air at a rate of rate of
between approximately 150 cubic feet per minute per square foot and
approximately 450 cubic feet per minute per square foot; and
wherein said second source of air is configured to circulate heated
air a rate of rate of between approximately 150 cubic feet per
minute per square foot and approximately 450 cubic feet per minute
per square foot; and wherein said third source of air is configured
to circulate heated air at a rate of rate of between approximately
150 cubic feet per minute per square foot and approximately 450
cubic feet per minute per square foot.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. provisional
application serial No. 60/235,066 filed on Sep. 25, 2000.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
REFERENCE TO A COMPUTER PROGRAM APPENDIX
[0003] Not Applicable
BACKGROUND OF THE INVENTION
[0004] 1. Field of the Invention
[0005] This invention pertains generally to dehydration devices and
methods, and more particularly to a desiccation method and
apparatus with multiple dehydration zones utilizing ultrasound,
heated circulating air and a substrate matrix.
[0006] 2. Description of the Background Art
[0007] The preservation of food and other organic and inorganic
material by the evaporation of water from the material is well
known in the art. Dehydration allows food to be kept for longer
periods of time without refrigeration. The size and weight of the
food is reduced by dehydration and the cost of transportation and
storage of the food is therefore minimized.
[0008] Early methods of dehydration consisted of placing whole or
diced food articles on trays and setting the trays in the sun for
several days to allow the food to dry. This method proved to be
undesirable on a commercial level because of the accumulation of
dust, molds and other air-borne particles on the food as well as
the discoloration of the food that often occurs upon exposure of
food to ultra-violet light. Furthermore, microbial levels in
sun-dehydrated foods were often unpredictable and unacceptable with
these early methods.
[0009] Mechanical kiln type dehydrating devices that isolated the
food from sunlight and outside air were then developed. These
devices passed heated air through perforated trays until the water
content of the food particles was reduced to a desired level.
However, these methods did not appreciably change the presence of
microbiological contaminants in many dehydrated foods, particularly
those that were dried at relatively low temperatures for
comparatively long periods of time. Although an improvement over
sun dehydration, the kiln type dehydration devices still produce
discolored foods in many instances due in part to the length of
time required to dry the foods.
[0010] In order to preserve the natural color and texture, many
dehydrated fruits were treated with sulfur dioxide, sulfites or
other chemical preservatives. For many people, the taste of the
preservatives made the treated foods undesirable. For others, the
preservatives posed a health risk leading to legislation limiting
the amount and types of preservatives that could be present in
various dehydrated foods.
[0011] Later methods sought to eliminate enzyme activity and reduce
the levels of bacteria and the like by blanching the food with
steam or hot water and then drying the food at high temperature.
Unfortunately, blanching may alter the flavor and texture of some
foods and may make other foods difficult to dehydrate because the
food absorbs water during the blanching process. Likewise, some
foods are sensitive to exposure to heat. High drying temperatures
may also adversely affect the color and flavor of dehydrated foods.
Furthermore, blanching methods are not always effective in
consistently reducing the microbial levels to acceptable
levels.
[0012] Recently developed methods of dehydration include treating
the food with an osmotic agent and then dehydrating the food with
heated air. Still other methods use heated vegetable oil and
treatment in reduced pressure environments. These methods are
unsatisfactory due to the residues left by the treating agents as
well as the expense of production.
[0013] Substantially microbe free dehydrated foods have been
produced by "freeze-drying" methods known in the art. Fruit and
vegetable products are typically frozen and the water removed by
sublimation in a low-pressure environment with these methods. The
cost of high capacity refrigeration systems and low-pressure
systems, as well as the cost of energy and maintenance, makes the
resulting food product expensive to manufacture using these
methods.
[0014] Some seasonal vegetables, such as onions and bell peppers
have a limited market life. For example, onions that are beyond
certain size limits are often tilled under in the field or
composted because the onions cannot be brought to market during the
season. As much as twenty-five percent of the yearly onion crop may
be wasted in this manner.
[0015] Only a small percentage of onions are currently dehydrated
because of the difficulty experienced dehydrating onions using
current methods. Presently, yellow onions may be frozen to preserve
the onion until the onions can be processed. In addition, diced
pieces of onion do not dry well because the pieces tend to stick
together due to the sugar content of the onion thereby creating
pockets of moisture. Bacteria are found in such moisture pockets
requiring the destruction of the onion pieces resulting in
additional waste and expense.
[0016] Materials other than food, such as medicinal herbs, may be
prepared using dehydration to provide material for encapsulation or
the like. Dehydration may also be used in the processing of sludge
or other organic matter as well as inorganic matter.
[0017] Accordingly, the principal challenge to current desiccation
methods is to generate a dehydrated product with natural colors,
textures and flavors that is free from microbiological
contamination and noxious residues. Thus, there is a need for an
effective and cost efficient desiccating apparatus and method that
can maintain the natural color, flavor and texture of the food
while keeping the microbial level within acceptable limits without
using additives or preservatives or costly desiccation machinery
and methods. The present invention satisfies these needs, as well
as others, and generally overcomes the deficiencies found in
existing equipment and methods.
BRIEF SUMMARY OF THE INVENTION
[0018] The present invention is a material desiccation apparatus
and associated method for producing dehydrated vegetables and the
like, that are substantially free of microbiological contaminants
and retain the natural color, flavor and texture of the vegetable
upon rehydration. The apparatus and method are particularly suited
for dehydrating vegetables such as onions that discolor using
current methods known in the art. However, the apparatus and method
may also be used to dehydrate non-food materials such as sludge as
well as inorganic materials.
[0019] By way of example, and not of limitation, the inventive
method comprises circulating a heated gas, such as air, over
prepared and sized food material, and optionally subjecting the
material to ultrasonic sound waves, until the moisture content of
the material is preferably reduced to approximately 5% to 10% of
its original content. The time of exposure, the ultrasonic
wavelength, the volume of gas, rate of gas flow, and the
temperature of the circulating gas can be varied in single or
multiple stages to control the overall rate of desiccation of the
material. In this way, the conditions and rate of desiccation and
can be tailored to the characteristics and type of food or other
material to be dehydrated. The exposure of the material to
ultrasound and the exposure to circulating gas are preferably done
simultaneously. However, the exposures may also be done in close
succession.
[0020] The preferred method of using the apparatus of the present
invention, applied to onions for example, will have at least one
stage and preferably three dehydration stages. While the preferred
method has three stages, it will be seen that any number of stages
can be utilized.
[0021] In the preferred first stage, the prepared and sized onions
are simultaneously subjected to ultrasound, preferably at
frequencies within the range of approximately 20 KHz to
approximately 100 KHz, and circulating heated air at a temperature
within the range of approximately 190.degree. F. to approximately
200.degree. F. for a period of approximately 13 to approximately 15
minutes. The flow of air is preferably approximately 240 cubic feet
per minute per square foot of drying bed in the first stage. The
ultrasonic emissions may be continuous or pulsed.
[0022] During the second stage, the onions are exposed to
ultrasound at frequencies within the range of approximately 20 KHz
to approximately 100 KHz and circulating heated air at a
temperature within the range of approximately 170.degree. F. to
approximately 180.degree. F. for a period of approximately 13 to
approximately 15 minutes. The flow of air is preferably
approximately 180 cubic feet per minute per square foot of drying
bed in the second stage.
[0023] In the third and final stage, the onions are subjected to
ultrasound at frequencies within the range of approximately 20 KHz
and approximately 100 KHz and circulating heated air at a
temperature within the range of approximately 150.degree. F. to
approximately 160.degree. F. for a period of about 60 minutes or as
needed to bring the water content of the onion pieces to
approximately 5% by weight. The preferred airflow is around 150
cubic feet per minute per square foot of drying bed in this
example.
[0024] While the method is tailored for onions as an example, it
will be understood that the temperature, ultrasonic frequencies,
number of stages, volume of circulating gas and time of exposure
may be varied in each stage depending on the type of material to be
dehydrated. Additionally, the use of ultrasound is optional and its
use, as well as the stages in connection with which ultrasound is
used, can vary depending on the particular product being dried.
[0025] According, the apparatus of the present invention generally
comprises a drying chamber having an optional ultrasound generator
along with intake and output ducts to allow heated air to circulate
in and through the chamber and out of the chamber. The food
material is preferably placed on a substrate comprising a plurality
of spheres. Although the spherical shape is preferred, it will be
understood that any shape substrate may be used.
[0026] The preferred embodiment has an elongate enclosure with a
number of vertical partitions defining three drying chambers. Each
drying chamber has an ultrasound emitter and air intake and output
ductwork. A horizontal, perforated conveyor belt, preferably with a
number of vertical vanes, runs longitudinally through the enclosure
and partitions. The endless conveyor belt is preferably
motorized.
[0027] The spheres and food material are placed between the
vertical vanes of the conveyor belt to a depth of about 24 inches
or less. Alternatively, the spheres and food material may be placed
in a perforated container. The ultrasound emitter and intake duct
in each drying chamber are preferably positioned below the
perforated conveyor belt and the output duct above the
conveyor.
[0028] In use, the spheres with the food material advance along the
perforated conveyor to the enclosure and the first drying chamber.
Heated air is brought through the intake duct and forced through
the perforated belt, around the spheres and the food particles to
the upper section of the chamber and out through the output duct.
After a defined period of time, the belt advances through a
partition into the second drying chamber. The second and third
drying chambers are preferably configured in the same manner as the
first drying chamber. However, the temperature of the input air and
the frequency of the ultrasound and the time of exposure may be
different from chamber to chamber. Optionally, the air intake of
the second drying chamber may be joined to the intake duct of the
third drying chamber, and so on, to conserve the heat.
[0029] After exiting the enclosure, the spheres are removed from
the conveyor belt and the desiccated food material is separated
from the spheres and thereafter prepared for packaging. In one
embodiment, the spheres and dried food particles are placed on a
vibrating perforated table to separate the spheres from the
dehydrated material.
[0030] An object of the invention is to provide an apparatus and
method to efficiently dehydrate material without being required to
blanch, freeze or treat the material with preservatives.
[0031] Another object of the invention is to provide a modular,
multi-stage desiccating apparatus that can efficiently and
economically dehydrate material by subjecting the material to
ultrasound and a circulating heated gas in each stage.
[0032] A further object of the present invention is to provide a
desiccating apparatus and method that will greatly reduce bacteria
and other microbial levels without significantly affecting the
flavor, texture and other characteristics of the dehydrated
materials upon rehydration.
[0033] Another object of the invention is to provide a device that
has variable desiccating conditions that can be adapted to provide
a range of dehydration rates allowing the efficient dehydration of
a variety of foods and other materials.
[0034] Yet another object of the invention is to provide a support
substrate that supports the material to be dehydrated to allow
faster and more efficient dehydration than found in conventional
dehydration devices.
[0035] Further objects and advantages of the invention will be
brought out in the following portions of the specification, wherein
the detailed description is for the purpose of fully disclosing
preferred embodiments of the invention without placing limitations
thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The invention will be more fully understood by reference to
the following drawings, which are for illustrative purposes
only:
[0037] FIG. 1 is a perspective view of an embodiment of a
desiccating apparatus according to the present invention having
three stages.
[0038] FIG. 2 is a side view of the desiccating apparatus of FIG. 1
showing the vaned conveyor belt configuration.
[0039] FIG. 3 is a side view of the desiccating apparatus of FIG. 1
with intake ducts, ultrasound emitters and belt portions depicted
in dashed lines.
[0040] FIG. 4 is a detailed partial interior side view of the first
stage of the desiccation apparatus of FIG. 1 shown with the support
substrate in one section of the drying bed.
[0041] FIG. 5 is a detailed side view of one section of the drying
bed shown in FIG. 4.
[0042] FIG. 6 is a side view of the separator portion of the
apparatus shown in FIG. 1 showing the separation of the dehydrated
material from the support substrate.
[0043] FIG. 7 is a side view of an alternative embodiment of the
present invention showing the ductwork connecting the output duct
of one drying chamber with the input duct of the subsequent chamber
allowing heat to be conserved.
DETAILED DESCRIPTION OF THE INVENTION
[0044] Referring more specifically to the drawings, for
illustrative purposes the present invention is embodied in the
apparatus generally shown in FIG. 1 through FIG. 7, where like
reference numbers denote like parts. It will be appreciated that
the apparatus may vary as to configuration and as to details of the
parts, and that the method may vary as to the specific steps and
sequence, without departing from the basic inventive concepts
disclosed herein.
[0045] Referring first to FIG. 1, the desiccation apparatus 10
according to the present invention preferably comprises multiple
linearly arranged drying chambers through which an endless
horizontal conveyor belt 12 generally moves in one direction. These
drying chambers are essentially stages or zones in an enclosure 14
through which the material to be dried can pass. Three stages are
provided in the embodiment shown in FIG. 1.
[0046] Conveyor belt 12 may optionally have vertical vanes 16 that
are generally perpendicular to the horizontal plane of the belt 12.
A motor 18 is mounted to enclosure 14 and provides motion to the
conveyor belt 12 at variable speeds as needed. Motor 18 may have
step down gearing with a first sprocket 20 and a second sprocket 22
to regulate the rate of advancement of conveyor belt 12 through the
enclosure 14. The conveyor belt 12 may quickly advance through each
stage at designated time points or may alternatively move very
slowly through the stages when the desired time of exposure of the
material in each stage is essentially the same.
[0047] Enclosure 14 has a front entry panel 24 and a rear exit
panel 26. The front and rear panels 24, 26 extend vertically from
the top of the enclosure to just above the tip of the vanes 16 of
the conveyor belt 12 so as not to interfere with the passage of the
belt 12 through the interior of enclosure 14. The front and rear
panels 24, 26 may be made of rigid steel or, alternatively,
flexible plastic and are configured to reduce the flow of air into
or out of the enclosure 14 through the place of entry or exit of
conveyor belt 12 from the enclosure 14.
[0048] Referring also to FIG. 2 and FIG. 3, it can be seen that
enclosure 14 has a top wall 28, and a bottom or floor 30 that is
supported by a left sidewall 32, and a right side wall 34. The
enclosure 14 and conveyor belt 12 are preferably supported by a
plurality of support legs 36 to position belt 12 at a level that
will allow a worker to place materials on conveyor belt 12 without
bending over.
[0049] Referring particularly to FIG. 2, in the embodiment shown
the interior of enclosure 14 is divided by inner vertical
partitions 38 and 40 to define discrete drying chambers. Partition
38 forms a first drying chamber 42. Partition 40 forms a second
drying chamber 44 and a third drying chamber 46 within enclosure
14. Both partitions 38 and 40 have an opening to allow conveyor
belt 12 and vanes 16 to move freely through drying chambers 42, 44
and 46. Conveyor belt 12 advances horizontally through enclosure
14, around a powered roller 48, below floor 30 and between the
support legs 36 to trailing roller 50. Alternatively, a perforated
container or platform (not shown) may be used instead of the vanes
16 of perforated conveyor 12 to hold the material to be
dehydrated.
[0050] Drying chamber 42 has an ultrasound emitter 52 preferably
positioned below conveyor belt 12 at or near bottom wall 30 of
enclosure 14. Likewise, the second and third drying chambers 44, 46
have ultrasound emitters 54 and 56 respectively positioned below
belt 12 within enclosure 14.
[0051] Each drying chamber preferably has discreet intake and
output ducts that allow heated air or gas to be directed through
each drying chamber. The volume and rate of flow of gas through
each of the input ducts for each chamber can be varied.
[0052] Intake duct 58 is positioned below conveyor belt 12 in the
first drying chamber 42. Conveyor belt 12 is preferably perforated
to allow air to flow through the belt. Output duct 60 is preferably
positioned at the top of wall 28 of the enclosure and first drying
chamber 42. Likewise, the second drying chamber 44 has input duct
62 and output duct 64 and the third drying chamber 46 has input
duct 66 and output duct 68 in similar configuration to the ducts of
the first drying chamber 42. While the input ducts and ultrasound
emitters are preferably placed below the perforated conveyor belt
12, it will be understood that the ultrasound emitters 52, 54, and
56 can be placed above the conveyor belt 12 and the air flow can
come from either above, below or to the side of belt 12 depending
on the placement of input ducts 58, 60 and 62.
[0053] It can be seen that enclosure 14 is modular. One or more
drying chambers can be sequentially added as needed to the first
drying chamber, each chamber having input and output ducts and,
optionally, an ultrasound emitter. The chambers may be contiguous
as in the embodiment shown or independent of the other
chambers.
[0054] The temperature of the air or gas that enters each drying
chamber 42, 44, 46 can be raised by heating the intake air or gas
using a furnace or other methods known in the art and commercially
available. The gas or air is forced through the furnace elements
and heated in this embodiment. The air then proceeds into the first
drying chamber 42 and is then preferably drawn out of the chamber
by a number of fans known in the art. The fans should be capable of
moving volumes of air from approximately 150 to approximately 450
cubic feet per minute per square foot through the drying chambers
42, 44 and 46. The volume of air directed through each drying
chamber can be increased or decreased to influence the overall rate
of dehydration by the apparatus.
[0055] For drying certain materials, it may be desirable to use a
heated inert gas such as Nitrogen as a medium rather than heated
air to reduce the amount of oxidization of the material.
Accordingly, the system could be closed and the inert gas recycled
without departing from the scope of the invention.
[0056] To conserve heat, a heat exchanger known in the art (not
shown) may be associated with output duct 60, as well as associated
air ducts, to transfer heat from the air exiting the first drying
chamber 42 to the incoming air of the second drying chamber 44
through intake duct 62. Heat exchangers may also be associated with
each output duct from each drying chamber to heat the air or gas
entering the input ductwork of each drying chamber.
[0057] Referring also to FIG. 4 and FIG. 5, the invention
preferably includes a drying bed that utilizes a support substrate.
The support substrate preferably comprises a plurality of spheres
70 held within vertical vanes 16 of conveyor belt 12 to form the
drying bed. Each area between each of the vanes 16 is filled with
spheres 70 and food particles 72. For clarity, FIG. 4 and FIG. 5
show only a single space filled between vanes 16. Alternatively,
the spheres 70 and food particles 72 may be placed in an open
container with perforated walls and bottom to support the drying
bed that is placed on a perforated conveyor or other support
structure.
[0058] Spheres 70 are preferably approximately 3/4 of an inch in
diameter and are made of heat resistant plastic or similar
material. The size of the spheres may be increased or decreased
depending on the type of material that is to be desiccated and the
size of the particles that are introduced into the apparatus. Food
particles, or other material 72 and spheres 70 can form a drying
bed of varying depths, but the bed preferably has a depth of
approximately twenty-four inches or less in the embodiment shown. A
drying bed of this type facilitates faster drying because the
spheres separate the product and increase the exposed surface area
of the product. While the drying bed is preferably composed of
spheres, it will be understood that the drying bed could be
composed of solids of virtually any shape. The use of spheres or
balls in connection with drying materials is described in more
detail in my prior patent, U.S. Pat. No. 5,522,156 issued on Jun.
4, 1996, incorporated herein by reference.
[0059] In use, food particles 72 or other items to be desiccated
are mixed with spheres 70 and placed on a loading section of
perforated conveyor belt 12 within sectioned areas formed by
vertical vanes 16 and left and right loading area sidewalls 74, 76.
In the embodiment shown, belt 12 and the material to be dehydrated
advance through the front entry panel 24 and into the first drying
chamber 42. Heated air is brought into chamber 42 through intake
duct 58 and forced through the perforations of conveyor belt 12.
The air then circulates through the spaces between spheres 70 and
food particles 72 and is drawn out of the chamber through output
duct 60. At the same time the food particles 72 are preferably
subject to pulsed or constant ultrasonic emissions from ultrasound
emitter 52.
[0060] At the appropriate time, the food or other matter is
conveyed from the first drying chamber 42 to the second drying
chamber 44 through an access way through partition 38. Air or other
heated gas enters chamber 44 through intake duct 62 and is forced
through the perforated conveyor belt 12 and around spheres 70 and
food particles 72 and out of the chamber through output duct 64. At
the same time, the food particles 72 are exposed to ultrasonic
emissions from ultrasound emitter 54. Emitter 54 may be set to emit
ultrasonic waves at a different frequency from emitter 52 in the
first drying chamber or may be set at the same frequency depending
on the type of food material 72 to be dehydrated. The temperature
and volume of the heated air or gas entering chamber 44 may also be
variable.
[0061] The material then enters the third drying chamber 46 through
an access way through partition 40. Heated air or gas enters the
third drying chamber 46 though intake duct 66 and is forced through
belt 12 around spheres 70 and food particles 72 and out through
output duct 68. Emitter 56 provides pulsed or constant ultrasonic
emissions to the third drying chamber 46 at desired
frequencies.
[0062] Finally, the materials exit the third drying chamber 46 and
enclosure 14 through rear exit panel 26. Referring to FIG. 6, the
dehydrated food particles 72 are separated from spheres 70 using a
vibrating table 78 or other commercial separator. Spheres 70 are
returned to a staging area for cleaning and mixing with new food
material in the embodiment shown. The separated dehydrated food
particles 72 are taken by conveyor 80 to be inspected and
packaged.
[0063] Turning now to FIG. 7, a heat conserving alternative
embodiment of the present invention is shown. In this
configuration, the air from the output duct of the previous drying
chamber is attached to the input duct of the subsequent chamber to
conserve heat. For example, output duct 64 of the second drying
chamber 44 may be connected to input duct 66 of the third drying
chamber 46 by a connecting pipe 82 with an optional fan. The heated
air from the second drying chamber 44 is recycled through the third
15 drying chamber 46 thereby conserving heat. However, the water
content of the air exiting the first drying chamber may often be
too high to effectively recycle the air from the first drying
chamber 42. If this is the case, the heat must be transferred
through the use of a heat exchanger.
[0064] It will be understood by one skilled in the art that the
drying chambers could be separate rather than contiguous as shown
in FIG.1 through FIG. 7. For example, the time of exposure of the
food particles may need to be different for each drying chamber
requiring different rates of advancement for the conveyor belt.
Therefore, separate belts and separate drying chambers would be
used without departing from the scope of the invention.
[0065] In practicing the methods of the invention, the matter to be
desiccated is initially prepared. The methods of the present
invention are particularly suited for desiccation of fruits and
vegetables and other plants as well as shrimp and certain cut
meats. Accordingly, preparation may include washing, peeling,
cutting, dicing, and precooking and the like depending on the
material to be dehydrated.
[0066] The prepared particulate food matter is then loaded into an
apparatus that is capable of providing variable temperature, gas or
airflow and pulsed or constant ultrasonic emissions over time. The
temperature, rate of airflow and the frequency of ultrasonic
emission and the sequence of exposures may vary depending on the
type of material that is to be dehydrated. The inventive methods
also contemplate that the ultrasonic frequency could be zero when
the spherical support substrate 72 is utilized in appropriate
circumstances. It will be seen that the variation of temperature,
airflow, time of exposure as well as the frequency of the
ultrasonic emissions may regulate the overall rate of
desiccation.
[0067] In order to further illustrate the inventive methods of the
present invention, the following non-limiting example is provided.
In this example, onions are washed, peeled and diced. The prepared
diced onions are preferably mixed with spheres 70 and loaded onto a
perforated conveyor 12. In phase one (drying chamber 42), the
onions are exposed to continuous ultrasound at a frequency of
approximately 20 KHz, and to circulating heated air at a
temperature between approximately 190.degree. F. and approximately
210.degree. F., preferably approximately 200.degree. F. at a rate
of approximately 240 cubic feet per minute per square foot of
drying bed for approximately fifteen minutes. As much as 70% of the
water content of the onion is removed in this phase as a result of
the spherical support substrate and the ultrasound exciting the
water molecules and the movement of water to the outer surface of
the onion.
[0068] In phase two (drying chamber 44), the diced onion is
subjected to continuous ultrasound at a frequency of approximately
20 KHz, and to circulating heated air at a temperature between
approximately 170.degree. F. and approximately 190.degree. F.,
preferably approximately 180.degree. F. at a rate of approximately
180 cubic feet per minute per square foot for approximately fifteen
minutes.
[0069] Finally, In phase three (drying chamber 46), the diced onion
is then subjected to continuous ultrasound at a frequency of
approximately 20 KHz, and to circulating heated air at a
temperature between approximately 150.degree. F. and approximately
170.degree. F., preferably 160.degree. F., at a rate of
approximately 150 cubic feet per minute per square foot of surface
area for approximately one hour until the moisture content of the
onion is approximately 5%. This level of moisture content makes the
product shelf stable; that is, it will have an indefinite shelf
life. The onion is then inspected and packaged.
[0070] By staging the drying process as described, the expulsion of
moisture is maximized without damaging the food. As the amount of
solids increases due to a reduction in moisture, the sensitivity of
the food product to temperature increases. Accordingly, the drying
temperature may be dropped in successive drying zones. Furthermore,
by subjecting the material to ultrasonic sound waves, the water
molecules in the material are excited and move to the outer surface
of the material, thus allowing for more efficient drying by the
circulating heated gas.
[0071] Current permissible bacterial counts in onions dehydrated
using conventional means have a standard total plate count of
approximately 300,000. Plate counts of 10,000, which are well below
permissible levels, have been observed in onions using the
apparatus and methods of the present invention.
[0072] Accordingly, it will be seen that the methods and apparatus
of this invention can efficiently and swiftly desiccate food
particles which are substantially free of microbial content without
the need for blanching, freezing, dehydrating at low pressures,
chemical treatments or other activities that may affect the color,
flavor and texture of the food upon rehydration.
[0073] Although the description above contains many specificities,
these should not be construed as limiting the scope of the
invention but as merely providing illustrations of some of the
presently preferred embodiments of this invention. Therefore, it
will be appreciated that the scope of the present invention fully
encompasses other embodiments which may become obvious to those
skilled in the art, and that the scope of the present invention is
accordingly to be limited by nothing other than the appended
claims, in which reference to an element in the singular is not
intended to mean "one and only one" unless explicitly so stated,
but rather "one or more." All structural, chemical, and functional
equivalents to the elements of the above-described preferred
embodiment that are known to those of ordinary skill in the art are
expressly incorporated herein by reference and are intended to be
encompassed by the present claims. Moreover, it is not necessary
for a device or method to address each and every problem sought to
be solved by the present invention, for it to be encompassed by the
present claims. Furthermore, no element, component, or method step
in the present disclosure is intended to be dedicated to the public
regardless of whether the element, component, or method step is
explicitly recited in the claims. No claim element herein is to be
construed under the provisions of 35 U.S.C. 112, sixth paragraph,
unless the element is expressly recited using the phrase "means
for."
* * * * *