U.S. patent application number 13/368195 was filed with the patent office on 2012-08-09 for counter-top produce refrigeration and ozonation system and method.
Invention is credited to Vincent M. ARRIGO.
Application Number | 20120198862 13/368195 |
Document ID | / |
Family ID | 46599730 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120198862 |
Kind Code |
A1 |
ARRIGO; Vincent M. |
August 9, 2012 |
COUNTER-TOP PRODUCE REFRIGERATION AND OZONATION SYSTEM AND
METHOD
Abstract
A produce storage chamber comprising a chamber capable of
encasing produce, a refrigeration system, at least one ozone
generation units, and at least one ethylene scrubbers. The chamber
is capable of delaying postharvest produce deterioration using at
least one of temperature control, ozone generation, and ethylene
scrubbing.
Inventors: |
ARRIGO; Vincent M.;
(Sarasota, FL) |
Family ID: |
46599730 |
Appl. No.: |
13/368195 |
Filed: |
February 7, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13013327 |
Jan 25, 2011 |
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13368195 |
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Current U.S.
Class: |
62/78 ;
62/457.9 |
Current CPC
Class: |
F25D 17/042 20130101;
F25D 2317/0416 20130101; F24F 2003/165 20130101; A23B 7/148
20130101; F24F 5/0042 20130101 |
Class at
Publication: |
62/78 ;
62/457.9 |
International
Class: |
F25D 3/00 20060101
F25D003/00; F24F 3/16 20060101 F24F003/16 |
Claims
1. A portable produce chamber of a sufficient size and dimension to
fit on a kitchen counter top surface, comprising: An outer shell
that substantially defines the size and shape of the produce
chamber; an inner chamber within the outer shell, the inner chamber
being of a sufficient size and dimension for the storage of
produce; a refrigeration system separated from the inner chamber by
an isolation plate; at least one ozone generation unit; at least
one ethylene scrubber; and a means with the chamber for controlling
temperature, ozone levels, and ethylene levels so to delay
postharvest produce deterioration.
2. The produce chamber of claim 1, further comprising means to
stack a portable produce chambers on another portable produce
chamber having a substantially similar construction.
3. The produce chamber of claim 1, wherein the produce chamber is a
first produce chamber having a size and dimension to be stacked on
a second produce chamber, the second produce chamber having
substantially the same size and dimension as the first produce
chamber.
4. The produce chamber of claim 1, wherein at least one ethylene
scrubber comprises potassium permanganate.
5. The produce chamber of claim 1, wherein at least one ethylene
scrubber comprises a titanium oxide photocatalyst.
6. The produce chamber of claim 1, wherein the ozone generator is a
high frequency coronal discharge ozone generator.
7. The produce chamber of claim 1, wherein the ozone generator
generates ozone with ultraviolet light.
8. The produce chamber of claim 1, wherein the refrigeration system
maintains chamber temperature from approximately 10.degree. C. to
20.degree. C.
9. The produce chamber of claim 1, the refrigeration system
maintains chamber temperature from approximately 12.degree. C. to
14.degree. C.
10. The produce chamber of claim 1, wherein the ozone generator
maintains the chamber ozone concentration from approximately 0.05
ppm to 0.1 ppm.
11. The produce chamber of claim 1, wherein the ozone generator
maintains the chamber ozone concentration from approximately 0.075
ppm to 0.095 ppm.
12. The produce chamber of claim 1, wherein chamber relative
humidity is maintained from approximately 80% to 100%.
13. The produce chamber of claim 1, wherein chamber ethylene
concentration is maintained at less than 0.015 ppm.
14. A portable produce chamber comprising: a housing having a size
and dimension to fit on a kitchen countertop, the housing
comprising an interior chamber capable of encasing produce; at
least one ethylene scrubbers within the interior chamber capable of
reducing chamber ethylene gas concentrations from the interior
chamber to delay postharvest produce deterioration; a refrigeration
system in communication with the interior chamber for the purpose
of maintaining an chamber temperature that delays postharvest
produce deterioration and for the purpose of maintaining a relative
humidity in the interior chamber that delays postharvest produce
deterioration; an isolation plate to separate components of the
refrigeration system from the interior chamber; and an ozone
generator in communication with the interior chamber for the
purpose of maintaining a chamber ozone concentration that delays
postharvest produce deterioration.
15. The produce chamber of claim 13, wherein at least one ethylene
scrubber comprises potassium permanganate.
16. The produce chamber of claim 13, wherein at least one ethylene
scrubber comprises a titanium oxide photocatalyst.
17. The produce chamber of claim 13, wherein the ozone generator is
a high frequency corona discharge ozone generator.
18. The produce chamber of claim 13, wherein the ozone generator
generates ozone with ultraviolet light.
19. The produce chamber of claim 13, wherein the refrigeration
system maintains chamber temperature from approximately 10.degree.
C. to 20.degree. C.
20. The produce chamber of claim 13, wherein chamber temperature is
maintained from 12.degree. C. to 14.degree. C.
21. The produce chamber of claim 13, wherein the ozone generator
maintains the chamber ozone concentration from approximately 0.05
ppm to 0.1 ppm.
22. The produce chamber of claim 13, wherein the ozone generator
maintains the chamber ozone concentration from approximately 0.075
ppm to 0.095 ppm.
23. The produce chamber of claim 13, wherein chamber relative
humidity is maintained from approximately 80% to 100%.
24. The produce chamber of claim 13, wherein chamber ethylene
concentration is maintained at less than 0.015 ppm.
25. A method of reducing postharvest produce deterioration
comprising the steps of: encasing the produce within an interior of
a portable produce chamber; separating a cooling system from the
interior of the produce chamber with an isolation plate; cooling
the interior of the produce chamber to a temperature from about
10.degree. C. to 20.degree. C.; introducing gaseous ozone into the
interior of a chamber to maintain a chamber ozone concentration
between about 0.05 ppm and 0.15 ppm; and maintaining a relative
humidity within the interior of the chamber ranging from about 80%
to 100% relative humidity.
26. The method of claim 24, further comprising the step of
scrubbing ethylene from the chamber.
27. The method of claim 24, wherein potassium permanganate is
introduced into the chamber for the purpose of ethylene
scrubbing.
28. The method of claim 24, wherein a titanium oxide photocatalyst
is used to scrub ethylene from the chamber.
29. The method of claim 24, wherein the ozone is generated by an
ozone generator in communication with the chamber.
30. The method of claim 24, further comprising the step of placing
the chamber on a counter top surface.
31. The method of claim 24, further comprising the step of stacking
the chamber on a second produce chamber.
32. The method of claim 24, wherein the chamber temperature is
maintained from 12.degree. C. to 14.degree. C.
33. The method of claim 24, wherein the chamber ozone concentration
is maintained from 0.075 ppm to 0.095 ppm.
34. The method of claim 24, wherein the chamber relative humidity
is maintained from 80% to 100%.
35. The method of claim 24, wherein ethylene concentration in the
chamber is maintained at less than 0.015 ppm.
36. A method of reducing postharvest produce deterioration
comprising the steps of: encasing produce within a portable,
stackable, counter top, produce chamber comprising a cooling
system, ozone generator, and ethylene scrubber; separating the
cooling system from the produce chamber using an isolation plate;
maintaining the chamber at a temperature from about 10.degree. C.
to 20.degree. C.; introducing gaseous ozone into the chamber to
maintain a chamber ozone concentration between about 0.05 ppm and
0.1 ppm; maintaining a relative humidity within the chamber ranging
from about 70% to 100% relative humidity; scrubbing ethylene from
the chamber with at least one potassium permanganate sachet; and
maintaining the chamber ethylene concentration at a level less than
about 0.015 ppm.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a Continuation in Part claiming priority
to U.S. patent application Ser. No. 13/013,327 filed on Jan. 25,
2011 entitled "Produce Refrigeration Chamber," the contents of
which are incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates to the field produce storage
chamber to reduce spoilage. More specifically, to a construction
designed to fit on a counter top.
BACKGROUND OF INVENTION
[0003] Due to various nutrient and antioxidant profiles,
consumption of fresh produce is generally accepted as essential to
a healthy diet. Regular consumption of fruit is associated with
reduced risks of cancer, cardiovascular disease (especially
coronary heart disease), stroke, Alzheimer's disease, cataracts,
and some of the general functional declines associated with aging.
Diets that include a sufficient amount of fruits and vegetables
also help reduce the chance of developing kidney stones and may
help reduce the effects of bone loss. Fruits are also low in
calories and are often integral to weight loss plans and generally
healthy, balanced diets.
[0004] Most fruits and vegetables ripen after they are removed from
their associated plants and stalks. Such ripening often changes the
characteristics of the produce, including altering sweetness
levels, texture, and firmness. Consumption of fruits and vegetables
at the optimal point in the ripening process helps maximize not
only taste and enjoyment of these foods, but may also maximize
their health benefits.
[0005] Ripening is a natural process which is primarily a result of
the production of ripening enzymes, many of which are triggered by
the release of ethylene by the produce. Ethylene is a simple
hydrocarbon gas produced when a fruit ripens, and is known to
promote the upregulation of genes that cause the expression of
enzymes that foster ripening. These enzymes may change the color of
the skin as chlorophyll is degraded, aid in the production of new
pigments, foster the breakdown of acids that make fruit taste sour,
convert starches into sweet sugars, and soften pectin.
[0006] Maintaining most fruits and vegetables in a sufficiently
cold state after harvest helps extend and ensure shelf life, most
notably by reducing the release of ethylene. However, storage of
produce in an isolated area without refrigeration causes a build up
of ethylene and results in faster ripening (and rotting) of fruits
and vegetable.
[0007] Due to the costs and life spans of harvested fruits and
vegetables, there have been many techniques developed to address
storage to maintain this cold chain. One such example is U.S. Pat.
No. 4,845,958 entitled "Method of and Apparatus for Preserving
Perishable Goods" to Senda. The apparatus taught by Senda relates
to a refrigerated housing that includes a humidifier and a
compression system to cool the housing. The device also uses an
ethyl alcohol spray to help odorize the ripening produce.
[0008] A second concept for preserving ripening produce is
introduced by U.S. Pat. No. 5,661,979 entitled "Self-contained
Refrigeration Device for Fruit" to Deboer. The Deboer patent
teaches a self contained refrigeration unit that uses
thermo-electric Peltier cooler, as well as a heat sink to dissipate
the heat generated by the cooler so to maintain a cooled container
to maintain produce. A double-headed fan facilitates airflow
throughout the assembly to aid in the removal of ethylene through a
vent tower.
[0009] Yet a third example of a system for preserving fruit and
vegetables is found in U.S. Pat. No. 5,782,094 entitled
"Refrigerated Countertop Snack Container" to Freeman. Akin to
Daboer, Freeman uses a Peltier thermoelectric element (instead of a
compressor) to cool a refrigeration container. Such container is
insulated and includes a series of air outlet and intake vents to
aide in circulating air about the produce in order to reduce
ethylene build up. The device further uses a series of fins and
baffles to aid in circulation.
[0010] Ozone is a pungent, naturally-occurring gas possessing
strong oxidizing properties, and has a long history of safe use in
the disinfection of water sources. Ozone rapidly attacks bacterial
cell walls and is generally thought to be a more effective
anti-pathogenic agent against plant spores and mammalian parasites
than chlorine. Ozone is reported to have 1.5 times the oxidizing
potential of chlorine, yet contact times for this antimicrobial
action are typically 4-5 times less than that of chlorine, all
without the unwanted byproducts associated with chlorine. Ozone is
also known to degrade ethylene.
[0011] As shown by the foregoing references, there are certain
limitations in current counter-top style devices used to maintain
fruits and vegetables. First, these devices are limited to using
the Peltier effect (or traditional vapor compression systems) in
combination with airflow to ward off the effects of ethylene build
up. Second, current designs are largely inefficient and consume
large levels of energy. Third, most of these designs fail to
provide effective treatment of the ethylene which is the root of
rotting and spoilage of the produce. Fourth, there are no
counter-top applications of produce storage that introduce ozone as
a means of preventing produce spoilage. Accordingly, there is a
need in the art of produce storage for an energy efficient and
robust chamber for use with fresh fruits and vegetables.
SUMMARY OF THE INVENTION
[0012] In view of the foregoing background, it is therefore an
object of the present invention to provide a table top, stackable,
produce chamber comprising a chamber capable of encasing produce,
having a refrigeration system, at least one ozone generation unit,
and at least one ethylene scrubbers. The chamber is therefore
capable of delaying postharvest produce deterioration using of
temperature control, ozone generation, and ethylene scrubbing.
[0013] In one embodiment, the present invention contemplates a
portable produce chamber comprising a housing having a size and
dimension to fit on a kitchen countertop, the housing comprising a
chamber capable of encasing produce. In one embodiment, the chamber
is shaped so that one chamber will securely stack on another
chamber of the same type. At least one ethylene scrubber is fitted
within the chamber capable of reducing chamber ethylene gas
concentrations to delay postharvest produce deterioration. The
chamber is in communication with a refrigeration system for the
purpose of maintaining a chamber temperature that delays
postharvest produce deterioration. Additionally, the refrigeration
system maintains a chamber relative humidity that delays
postharvest produce deterioration. Lastly, an ozone generator in
communication with the chamber maintains a chamber ozone
concentration for the purpose of delaying postharvest produce
deterioration.
[0014] The invention also contemplates a method of reducing
postharvest produce deterioration comprising the steps of: placing
produce in a chamber; encasing the produce within the chamber;
cooling the chamber to a temperature from about 10.degree. C. to
20.degree. C.; introducing gaseous ozone into the chamber to
maintain a chamber ozone concentration between about 0.05 ppm and
0.1 ppm; and maintaining a relative humidity within the chamber
ranging from about 70% to 100% relative humidity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] For a fuller understanding of the invention, reference is
made to the following detailed description, taken in connection
with the accompanying drawings illustrating various embodiments of
the present invention, in which:
[0016] FIG. 1 is a perspective view of the produce chamber;
[0017] FIG. 2 is a right side view of the produce chamber;
[0018] FIG. 3 is a left side view of the produce chamber;
[0019] FIG. 4 is front view of the produce chamber;
[0020] FIG. 5 is an exploded view of the components of the produce
chamber;
[0021] FIG. 6 is a perspective view of the refrigeration system
within the produce chamber; and
[0022] FIG. 7 illustrates the preferred thermoelectric plate (TE)
used within the produce chamber.
[0023] FIG. 8 is a diagram of one embodiment of an ozone generator
circuit.
DETAILED DESCRIPTION OF THE INVENTION
[0024] In the Summary of the Invention above and in the Detailed
Description of the Invention and in the accompanying drawings,
reference is made to particular features (including method steps)
of the invention. It is to be understood that the disclosure of the
invention in this specification includes all possible combinations
of such particular features. For example, where a particular
feature is disclosed in the context of a particular aspect or
embodiment of the invention, that feature can also be used, to the
extent possible, in combination with and/or in the context of other
particular aspects and embodiments of the invention, and in the
invention generally.
[0025] The term "comprises" is used herein to mean that other
elements, steps, etc. are optionally present. When reference is
made herein to a method comprising two or more defined steps, the
steps can be carried in any order or simultaneously (except where
the context excludes that possibility), and the method can include
at least one steps which are carried out before any of the defined
steps, between two of the defined steps, or after all of the
defined steps (except where the context excludes that
possibility).
[0026] In this section, the present invention will be described
more fully with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will convey the scope of the invention
to those skilled in the art.
[0027] As illustrated in FIGS. 1 through 6, the invention is
directed to a produce chamber 100 used to store fruits, vegetables
other related perishable foods to ensure ripeness. The produce
chamber 100 helps regulate the temperature and humidity of fruits
and vegetables and to ensure regulated and reduced levels of
ethylene. In doing so, the produce chamber 100 helps maintain the
proper ripeness of produce stored within its confines. While the
invention contemplates a design for use on a kitchen countertop,
the underlying technology can be used in related units, including
produce chambers 100 that are stackable (i.e., for use as displays
at grocers to maintain fruits and vegetables), and produce chamber
100 that are equal in size to current grocery store refrigeration
units.
[0028] As shown in FIG. 1-5, the components 101 of the produce
chamber 100 comprises an outer housing 200, a door 300 maintained
by the outer housing 200, a refrigeration system 400 and a
controller 500 to help regulate temperature, humidity, ozone, and
ethylene concentration. In addition, the invention contemplates
placement of a series of perforated trays 600 and a produce hook
630 within the outer housing 200 which help hold and maintain the
stored produce. Other additional and related components will be
known and understood by those of ordinary skill in the art upon
review of the figures and this disclosure.
The Outer Housing
[0029] FIGS. 1 through 5 illustrate, by way of example, one
embodiment contemplated by the invention for the outer housing 200.
First turning to FIG. 1, the outer housing 200 may include a first
side panel 210, a second side panel 220 and a base plate 230 (shown
in greater detail in FIG. 5). The side panels 210 and 220 are
essentially parallel to one another in order to form two respective
ends of the produce chamber 100. The base plate 230 is
inter-dispersed between both side panels 210 and 220. Combination
of these panels 210 and 220, as well as the base plate 230 function
as the outer casing of the outer housing 200. This provides a rigid
shell for the outer housing 200 in order to protect the integrity
of the stored fruits and vegetables. What is more, such rigid shell
further serves as a platform in which the various interior
components 101 (shown in FIG. 5) are maintained and held within the
produce chamber 100.
[0030] FIG. 2 further illustrates one preferred shape, structure,
and configuration for the first side panel 210. The first side
panel 210 not only functions as part of the rigid outer housing
200, but also maintains two primary components of the produce
chamber 100. As shown in FIG. 2 (as well as FIG. 5), the first side
panel 210 has a sufficient shape to house both the refrigeration
system 400 and the controller 500. The first panel 210 further
allows for the separation of the cold and hot sides of the
refrigeration system 400 as well as to cool the various components
housed by the first panel 210. Moreover, this allows circulation of
cooled, ozonated, and humidity controlled air inside the produce
chamber 100 for purposes of removing ethylene and inhibiting
microbe proliferation.
[0031] As shown in both FIG. 1 and FIG. 2, the first panel 210 is
preferably a circular disk 211 having an essentially flat bottom
portion 212. The bottom portion 212 illustrated in FIG. 2 mirrors
the width of the base plate 230 (shown in FIG. 4). As also shown in
FIG. 5, the base plate 230 perpendicularly engages the first flat
wall 213 of the first side panel 210. This allows the bottom
portion 212, and accordingly the entire produce chamber 100, to
rest on a flat surface like a kitchen countertop--or alternatively
a display counter (such as in a grocery store). Of course, other
shapes, such as a substantially rectangular produce chamber 100 are
also contemplated by this disclosure.
[0032] Turning back to FIG. 1 (and also to FIG. 4), the structure
of the first panel 210 also includes an isolation plate 214 (in
addition to the first flat wall 213 and the bottom portion 212).
The isolation plate 214 is essentially circular, conforming to the
shape of the bottom portion 212. Moreover, the isolation plate 214
has a sufficient wall thickness so as to house and maintain the
various components 101--which may include both the refrigeration
system 400 and the controller 500 in a separate compartment from
the main produce-storing chamber of the produce chamber 100.
[0033] As shown in both FIG. 1 and FIG. 2, both the first flat wall
213 and the isolation plate 214 may include a series of vents 216.
As shown, these vents 216 preferably include a side vent 217, a
panel vent 218 and a fan vent 219. As shown in greater detail in
FIG. 5, the primary function of the side vent 217 and the panel
vent 218 is to allow the hot side heat sink fan 482 (shown in FIG.
7) to pull ambient air in through the side vent 217 and the panel
vent 218, move it across the hot side heat sink 481 and then push
the now hot air out through fan vent 219 so as to remove heat from
the refrigeration system 400. The secondary purpose is to pull
ambient air in through the side vent 217 and panel vent 218 to cool
the controller 500.
[0034] Both FIG. 3 and FIG. 5 illustrate, by way of example, the
structure, positioning and features of the second panel 220. As
shown, the second panel 220 mirrors the size and dimension of the
first panel 210. Furthermore, the second panel 220 comprises a
circular disk 221 having a second flat wall 223, a second flat
bottom portion 222, and a second ring 224 of similar construction
compared to the first panel 210. Such bottom portion 222 mirrors
the width of the base plate 230 (again shown in FIG. 1 and FIG.
5).
[0035] FIG. 5 illustrates, by way of example, the structure and
features of the base plate 230. As shown, the base plate 230
preferably includes a front raised edge 231, a bottom panel 232, a
back raised edge 233 and a divider groove 234. The front raised
edge helps engage and creating a sealing relationship with the door
300. Similarly, the back raised edge 233 both meets and connects to
the back panel 350. The divider groove 235 is a slit that has a
sufficient length and depth so as to engage and maintain at least
one perforated trays 600.
The Door and Back Panel
[0036] Both FIG. 4 and FIG. 5 illustrate, by way of example, the
structure and characteristics of both the door 300 (which
optionally may be translucent) and the back panel 350 which, along
with the outer housing 200, form the exterior of the produce
chamber 100. First turning to FIG. 4, the door 300 includes a first
edge 301, a corresponding second edge 302, a top edge 303 and a
corresponding bottom edge 304. Moreover, at least a portion of the
door 300 is preferably transparent and accordingly "see
through"--such that a user may be able to view the condition and
quantity of fruits and vegetables within the produce chamber 100.
Preferably, a handle 340 is positioned proximate the bottom edge
304 of the door 300. The handle 340 helps make it easier to lift up
and open the door 300 to retrieve (or alternatively store)
produce.
[0037] As shown in FIG. 5, the first edge 301 of the door 300 is
preferably arced. This curvature should be substantially the same
as that of the isolation plate 214 of the first panel 210.
Likewise, the second edge 302 should have curve that mirrors that
of the second ring 224 of the second panel 220. Accordingly, when
the door 300 is shut, a seal 310 forms between the first edge 301
and the isolation plate 214 (and correspondingly, the second edge
302 and the second ring 224). In addition, the bottom edge 304
forms a bottom seal 320 with the front raised edge 231 of the base
plate 230.
[0038] FIG. 1-5 further illustrates, by way of example, the salient
components 101 of the back panel 350. As shown, the back panel 350
includes a first edge 351, a corresponding second edge 352, a top
edge 353, and a bottom edge 354. The first edge 351 is sufficiently
curved to match the shape of the first panel 210, while the second
edge 352 is likewise arced to mirror the diameter of the second
panel 220. As further shown, the bottom edge 354 forms a bottom
seal 360 with the back raised edge 233 of the bottom plate 230.
[0039] A top hinge 390 connects the top edge 301 of the door 300
with the top edge 351 of the back panel 350. As shown, the top
hinge 390 allows the door 300 to swivel open and allow access the
various fruits and vegetables within the produce chamber 100.
Optionally, the back panel 350 may include an insulating layer 380.
This insulating layer can be sandwiched between the back panel 350
and an interior panel 385. Such insulating layer 380 increases the
efficiency of the system and reduces the need for the refrigeration
system 400 to constantly run to provide cooled air within the
produce chamber 100.
Perforated Trays
[0040] FIG. 5 further illustrates, by way of example, the
positioning and orientation of the perforated trays 600 within the
produce chamber 100. As shown, the perforated trays 600 preferably
include a horizontal tray 610 and a corresponding vertical tray
620. Both trays 610 and 620 include a plurality of holes 601 to
allow air to circulate. This helps ensure the reduction of ethylene
within the produce chamber 100, as well as regulated internal
temperature monitored by the controller 500.
[0041] As further shown in FIG. 5, the horizontal tray 610 is
maintained through a slit 611 found within the second panel 220. In
contrast, the vertical tray 620 is maintained by both the
horizontal tray 610 as well as the divider groove 234 located on
the base plate 230. Optionally, a hook 630 can be affixed to the
top hinge 390 sufficient to hold and maintain bananas and similar
fruits within the produce chamber 100.
The Refrigeration System
[0042] Both FIG. 5 and FIG. 6 illustrate, by way of example, one
embodiment of the refrigeration system 400. While several
refrigeration systems 400 are capable of being used within the
produce chamber 100, the invention contemplates utilization of a
cooling means, comprising at least one of an ammonium absorption
(AAF) system 410, a Peltier effect thermoelectric (TE) cooling
system 450, or a vapor-compression refrigeration (VCR) system (not
shown). While FIG. 5 illustrates this two-part refrigeration system
400, the invention also teaches use of just a single AAF system 410
without need for the TE system 450 or use of a single TE system 450
without the need for an AAF system 410, or the use or a single VCR
system, or the use of a VCR system combined with a TE 450 or an AAF
410 system.
[0043] Both FIG. 5 and FIG. 7 illustrate a TE system 450 generally
comprised of a thermoelectric (TE) module 460 which is comprised of
a cold side plate 470 and a hot side plate 480 and corresponding
cold side heat sink 471 and cold side heat sink fan 472 and hot
side heat sink 481 and hot side heat sink fan 482. When electricity
is applied to the TE module 460 the cold side plate 470 cools down
and the hot side plate 480 heats up. A cold side heat sink 471 is
thermally coupled to the cold side plate 470 which allows heat to
be efficiently transferred from the inside of the produce chamber
100 to the cold side plate 470. A cold side heat sink fan 472
increases the efficiency of the entire system. The cold side heat
sink fan 472 also works to keep the air within the produce chamber
100 moving through the zeolite filter 491.
[0044] As further illustrated by FIG. 7, heat absorbed by the cold
side plate 470 is transferred to the hot side plate 480. This heat
is transferred through the thermally coupled hot side heat sink 481
which located outside of the produce chamber 100. The hot side heat
sink fan 482 is used to efficiently remove the heat from the hot
side heat sink 481. This heat is vented out through the fan vent
219.
[0045] FIG. 5 illustrates an AAF system 410 comprised of a boiler
420, ammonia 421, a condenser 422, an evaporator 423, a storage
tank 424, and an absorber 425. A concentrated ammonia solution 421
is heated in the boiler 420 and driven off as vapor. The
pressurized ammonia 421 gas is then liquefied in a condenser 422.
Supplied with hydrogen, it evaporates in the evaporator 423 and
extracts heat from the storage container 424. The ammonia 421 gas
then enters the absorber 425 where it is reabsorbed in a weak
solution of ammonia 421. Finally, the saturated solution flows back
to the boiler 420 where the whole cycle starts again.
[0046] FIG. 6 illustrates one arrangement for the various
components 101 of the two-part refrigeration system. Since the TE
system 450 cools the produce chamber 100 by extracting heat from
it. This heat must ultimately be removed from the entire produce
chamber 100. In turn, the AAF system 410 starts by heating ammonia
421 in the boiler 420. The boiler 420 can be heated by any number
of means; all that matters is that heat is provided to the boiler
420. The invention specifically contemplates combination of both a
TE system 450 and an AAF system 410, wherein the heat from the TE
system 450 hot side heat sink 481, (which is normally wasted energy
that must be removed from the produce chamber 100), be used to heat
the AAF system 410 boiler 420. By using what would normally be
wasted heat from the TE system 450 to drive the AAF system 410, the
overall efficiency of the produce chamber 100 is dramatically
increased.
The Controller and Scrubber
[0047] The controller 500 is best illustrated in FIG. 5. There are
three primary functions of the controller 500 contemplated by the
invention. First, the controller 500 constantly monitors the
temperature and humidity within the produce chamber 100. Such
information may be displayed by a digital readout 510 positioned
and located on the first panel 210. Second, the controller 500
operates the refrigeration system 400. Such operation may include
determining when to turn on the AAF system 410 and/or the TE system
450.
[0048] As a third duty, the controller 500 can also opt to
circulate already cooled air within the produce chamber through a
scrubber 490--for purposes of removing toxins such as ethylene
which may lead to premature ripening of the fruits and vegetables
contained within the produce chamber 100.
Ethylene Scrubbing
[0049] To foster ethylene removal from the produce chamber 100,
media for the purpose of scrubbing ethylene from the air is present
in the produce chamber 100. The media is at least one of activated
alumina, vermiculite, zeolite, and silica gel. The media is
impregnated with potassium permanganate (KMnO.sub.4). The mass of
media utilized is tailored to the size of the produce chamber 100.
Media pore size, pore volume, surface area, and bulk density is
also tailored to the size of the produce chamber 100. Media with
lower bulk density is desired over the same mass of media
possessing a higher bulk density, due to the greater surface area
of the lower bulk density media providing greater availability of
KMnO.sub.4 to ethylene gas. The mass, pore size, pore volume,
surface area, and bulk density required for the produce chamber 100
will be readily apparent to those skilled in the art. The media
performs two primary functions: 1) to provide an absorptive surface
to trap ethylene gas molecules, and 2) to provide a substrate on
which KMnO.sub.4 is carried. KMnO.sub.4 is an oxidizing agent that
reacts with ethylene, oxidizing it to ethylene glycol which does
not markedly affect produce ripening. The produce chamber 100, in a
preferred embodiment, comprises at least one sachet containing 5 mg
KMnO.sub.4 impregnated zeolite. Besides or in conjunction with
sachets, KMnO.sub.4 impregnated filters and pellets may be used in
the chamber 100. In another embodiment, ultraviolet light mediated
photcatalysis of titanium oxide reduces ethylene levels in the
produce chamber 100 (the ultraviolet light source is optically
sequestered from the produce). In one embodiment of the produce
chamber 100, at least one dedicated pocket, bag, shelf, hook, or
net provides a location for at least one sachet containing ethylene
scrubbing media.
[0050] Titanium dioxide is known to be a photocatalyst under
ultraviolet (UV) light. When Titanium dioxide is spiked with
nitrogen ions or doped with metal oxide like tungsten trioxide, it
is also a photocatalyst under either visible or UV light. The
titanium dioxide photocatalytic reaction breaks down ethylene gas
into carbon dioxide and water vapor. Additionally, photocatalytic
oxidation provides the added benefit of reducing bacteria, molds,
and odors. In one embodiment of the invention, a titanium dioxide
photocatalyst is in communication with the produce chamber 100 for
the purpose of scrubbing ethylene gas and preventing the premature
ripening and spoiling of the fruits and vegetables contained within
the produce chamber 100.
Ozone Generation
[0051] Ozone cannot be stored and transported like most other
industrial gases, so must therefore be locally produced. Ozone can
be produced in a number of ways known in the art. The most common
methods are by the use of ultraviolet light and coronal
discharge.
[0052] In one embodiment of the invention ozone is generated with
an ultraviolet (UV) lamp. A UV lamp emitting light at approximately
185 nm in the presences of air (which is approximately 21% oxygen)
will cause some diatomic oxygen (O.sub.2) molecules to split,
resulting in single oxygen atoms (O.sup.-) that bind to other
diatomic oxygen molecules to form ozone (O.sub.3). UV mediated
ozone generation is advantageous in the current invention, for it
is not susceptible to nitric oxide formation, as are some corona
discharge-based devices operating in a humid environment.
[0053] The coronal discharge method of ozone is employed for many
industrial and personal uses. While multiple variations of the "hot
spark" coronal discharge method of ozone production exist, these
units usually work by means of a coronal discharge tube. Coronal
discharge tubes are typically cost-effective and do not require an
oxygen source other than the ambient air to produce ozone. In one
embodiment of the invention, ozone is generated with a corona
discharge device. In such a device, air passes through an
electrical field wherein ozone is generated. The preferred
embodiment of an ozone generator is a variation of the coronal
discharge method.
[0054] FIG. 8 illustrates one embodiment of a circuit 80 used to
drive the generation of ozone via coronal discharge. This circuit
80 comprises a silicon controlled rectifier Q1, which is a PNPN
four-layer semiconductor device that normally acts as an open
circuit, but switches rapidly to a conducting state when an
appropriate gate signal is applied to the gate terminal. In this
application, it operates as a full wave rectified high voltage
on-off generator to drive the primary winding of step up
transformer T001. As the forward voltage across the anode and
cathode is adjusted by the potentiometer R5, the amount of current
into the transformer and the rate of oscillation is controlled.
[0055] A suppression ("snubber") circuit comprising a resister R4
and capacitor C2 protect the silicon controlled rectifier Q1 from
overvoltage damage. Gate turn-on current is supplied by resister
R2. Diodes D2 and D3 complete the full wave circuit. Capacitor C1
provides alternating current isolation as well as adequate current
to drive the circuit 80.
[0056] A glass electrode 82 in communication with the circuit 80 of
is ultimately responsible for the production of ozone. As the
primary winding of the transformer T001 is excited, the secondary
winding of the transformer T001 drives a high voltage potential
into a coiled metal element inside the electrode 82 that exceeds
the dielectric breakdown of dry air, which in turn excites
electrons to produce a positive corona that is initiated by an
exogenous ionization event in a region of high potential gradient.
The electrons resulting from the ionization are attracted toward
the coiled electrode, and the positive ions repelled from it. By
undergoing inelastic collisions closer and closer to the curved
electrode, additional molecules are ionized in an electron cascade.
The electron collisions excite the positive ions so that photons of
short wavelength light are emitted. It is this that gives a
blue-purple corona discharge its characteristic glow. These photons
play an important part in producing the new seed electrons which
are required to sustain the corona and for ozone to be continuously
produced. The levels of ozone produced by this circuit and
electrode combination, when installed in the produce chamber are
between 0.05 ppm and 0.1 ppm ozone, and preferable at around 0.09
ppm. Because of the high reactivity of ozone, materials employed in
electrode construction include stainless steel (quality 316L),
titanium, aluminum (as long as no moisture is present), glass,
polytetrafluorethylene, or polyvinylidene fluoride. Silicone
rubbers may also be employed since ozone concentrations in the
present invention are relatively low.
Method of Reducing Postharvest Produce Deterioration
[0057] The present invention contemplates a method of reducing the
severity of postharvest produce deterioration. The method
preferably utilizes the produce chamber 100 described herein. The
method includes the step of placing of produce in a chamber of a
suitable size and dimension to encase the produce. The produce
chamber 100 is capable of being substantially sealed. The chamber
is cooled to a temperature ranging from 10.degree. C. to 20.degree.
C., with the preferred temperature being 13.degree. C.
Additionally, ozone is introduced into the chamber so that a
chamber ozone concentration is maintained from 0.05 ppm to 0.1 ppm,
with a preferred concentration range between 0.075 ppm and 0.95
ppm. In a preferred embodiment, a high cutoff point of
approximately 0.09 ppm ozone is maintained to ensure that ozone
levels remain below permissible levels as established by
Occupational Health and Safety Administration (OSHA) regulations.
In a preferred embodiment, the ozone is introduced into the chamber
100 by an ozone generator that is installed within the chamber. In
one embodiment, ethylene is scrubbed from the chamber environment.
In a preferred embodiment, ethylene concentrations within the
chamber remain below 0.015 ppm. Preferably, 5-gram sachets of
potassium permanganate are placed within the chamber 100 for the
purpose of ethylene scrubbing, though other methods of ethylene
scrubbing will be clear to those skilled in the art. The step of
maintaining a relative humidity from 70% to 100% within the chamber
is also contemplated with a preferred relative humidity level being
about 95%. The chamber 100 is placed on a counter top surface, such
that as found in a residential or commercial kitchen environment.
In an alternative embodiment, one chamber 100 is stacked on another
chamber 100 so that multiple chambers form a stacked chamber
array.
Examples and Experimental Data
[0058] The following experimental data compared the post-harvest
degradation of bananas and tomatoes in various conditions. The
control ("room condition") temperatures ranged from approximately
22.degree. C. to 25.degree. C., while experimental refrigerated
temperatures ranged from approximately 12.degree. C. to 15.degree.
C. Relative humidity for control groups was maintained at
approximately 25% RH to 50% RH, while experimental groups were
maintained between approximately 85% RH to 100% RH. Ethylene gas
concentrations were maintained in control groups between
approximately 0.02 ppm and 0.035 ppm, while some experimental
groups were maintained between approximately 0.0 ppm and 0.01 ppm.
Ozone was not introduced in control groups, while some experimental
groups were maintained between approximately 0.08 ppm and 0.095 ppm
ozone, which is within the acceptable level range allowed by the
Occupational Safety and Health Administration (OSHA) regulations
for such an application.
TABLE-US-00001 TABLE 1 Moisture Loss per Banana/Tomato (after 21
Days) BANANA TOMATO % Moisture % Moisture STORAGE CONDITION Mass
Loss Mass Loss OZONE TREATED 18.1 g 10.5% 3.4 g 2.6% (13.degree.
C.) OZONE + ETHYLENE 12.1 g 5.3% 2.1 g 1.6% SCRUBBING (13.degree.
C.) AMBIENT/ROOM 86.2 g 38.4% 7.2 g 5.5% TEMPERATURE *Note: The
standard error of the mean between treatments for bananas is 27.8 g
and for tomatoes is 1.5 g
[0059] Bananas and tomatoes were generally weighed every 2 days to
track moisture loss. Table 1 summarizes the amount of moisture lost
per individual banana or tomato for each storage condition. There
was only a minimal discrepancy between the amount of moisture lost
in the two 13.degree. C. storage treatments. Moisture loss was
lower in the treatment with additional ethylene scrubbing for both
bananas and tomatoes, but the difference was within the standard
error and thus was not statistically significant. However, fruit
left exposed to the ambient/room temperature conditions were found
to lose much more moisture. From these results, it can be concluded
that lower temperatures with higher RH result in improved water
retention in these fruit. Furthermore, it is possible that the
removal of additional ethylene using ethylene scrubbing sachets may
improve the water retention.
TABLE-US-00002 TABLE 2 Banana Firmness Evaluated at 6 mm
Deformation (Force in kg) OZONE & ETHYLNE OZONE SCRUBBING CONT
(ROOM (13.degree. C.) (13.degree. C.) TEMPERATURE) DAY 0 4.226
4.159 4.191 DAY 6 3.522 3.772 1.973 DAY 12 3.031 3.438 1.052 DAY 14
2.869 3.381 0.601 DAY 16 2.972 3.656 0.391 DAY 19 2.557 3.013 0.356
DAY 21 2.534 3.128 0.402
[0060] Table 2 shows that bananas in both of the 13.degree. C.
storage treatments exhibited improved preservation of firmness over
bananas in ambient/room conditions. This is indicated by higher
force values for the bananas stored at 13.degree. C., particularly
with the bananas in the ozone with ethylene scrubbing treatment.
Thus, the treatment with ozone and ethylene scrubbing provided
better preservation of firmness over the treatment with ozone
only.
TABLE-US-00003 TABLE 3 Tomato Firmness Evaluated at 3 mm
Deformation (Force in kg) OZONE OZONE & ETHYLNE CONT (ROOM
(13.degree. C.) SCRUBBING (13.degree. C.) TEMPERATURE) DAY 0 3.004
2.988 2.959 DAY 06 2.354 2.418 1.533 DAY 12 2.168 2.291 1.192 DAY
14 2.187 2.197 1.207 DAY 16 2.142 1.967 1.367 DAY 19 1.825 1.541
1.197 DAY 21 1.619 1.468 1.082
[0061] Table 3 shows that tomatoes in the 13.degree. C. storage
treatments generally exhibited improved preservation of firmness
compared with tomatoes in the ambient/room temperature treatment.
This is indicated by elevated force values for the tomatoes stored
in 13.degree. C. storage conditions compared with the lower force
values observed with tomatoes stored in the ambient/room
conditions. Minimal distinction can be seen between the firmness in
tomatoes stored in the ozone treatment and the treatment with ozone
and ethylene scrubbing.
[0062] Ozone concentration in the 13.degree. C. storage treatments
were effectively regulated and maintained within permissible levels
as established by OSHA regulations. The presence of ozone in the
13.degree. C. treatments effectively reduced the ethylene
concentration by about 2/3, while the treatment with additional
ethylene scrubbing further reduced the ethylene concentration to
essentially negligible levels.
[0063] The tomatoes and bananas that were held in the ambient/room
temperature conditions on the countertop were observed to be
exceptionally shriveled and soft after only 6 and 12 days,
respectively. Tomatoes in this storage condition were also found to
have mold growth after 14 days particularly near the stem end. It
was also determined that produce exposed to the ambient/room
temperature conditions lost a significant amount of moisture over
the 21 day trial. Furthermore, firmness measurements using a
Texture Analyzer Plus (Stable Micro Systems) found that both the
bananas and tomatoes had severely softened in the room temperature
storage condition. Thus, storage in the ambient/room temperature
treatment resulted in considerably diminished produce quality.
[0064] Bananas and tomatoes held at 13.degree. C. exhibited
significantly better maintenance of quality compared with produce
stored in the ambient/room temperature conditions. Water retention
was further improved in the treatment using ozone with additional
ethylene scrubbing. Better color retention was also observed for
both the bananas and tomatoes that received ozone with ethylene
scrubbing. Greater levels of brown-spotting were observed in the
bananas treated with only ozone than those treated with ozone and
ethylene scrubbing. Additionally, more extensive shriveling and
tearing of tomato flesh was observed with only ozone than with
ozone plus ethylene scrubbing. Banana firmness was also best
preserved in the fruit stored in the ozone with ethylene scrubbing
treatment. Thus, storage at 13.degree. C. using ozone with
additional ethylene scrubbing resulted in the highest quality
produce.
* * * * *