Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
1. The Field of the Invention
This invention relates generally to the storage, both
fixed and movable, of fresh produce, and, more particularly, to
such storage-and shipment in refrigerated containers containing
a preservative modified gaseous environment.
2. Deseription of the Prior Art
In U. S. patent 2,490,951, FOOD TREATMENT PROCESS, by
M. E. Dunkley, undesirable enzymic action which produces
spoilage of food products is sought to be eliminated or sharply
deterred by enclosing the food produets in a special gaseous
atmosphere of carbon monoxide and aeetylene, which gaseous
atmosphere is otherwise noted for its substantial lack of
atmospherie oxygen (less than 0.50%). In order to maintain the
speeified eomposition of gases, and in particular the low
oxygen content, the food produet and speeial gaseous atmosphere
must, according to this patent, be maintained in a sealed
eontainer.
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U. S. patent-~74~4~, STORAGE OF FRESH LEAFY :~
VEGETABLES by John W. MeGill, discloses a method of treating
fresh leafy vegetables in whieh they are maintained in an
atmosphere of 1~o~5% earbon monoxide, 1%-10~ oxygen, not more ;
than 5~ carbon dioxide, and the remainder nitrogen.
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- SUMM~RY ~ND DESCRIPTION OF THE INVENTION
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In the pxactice of the present discovery, fresh fruits
and vegetables are stored under refrigerated conditions fox
extended periods of time iIl a manner which prevents the growth
of harmful fungi, and, as well, thé environmental atmosphere is
a chemical anti-oxidant. All of the above are achieved by
maintaining the fresh produce in a storage container including
an artificial atmosphere composed of carbon monoxide
substantially in excess of 5% and preferably above about 10%,
carbon dioxide, a significant amount of oxygen, and the remainder
nitrogen.
As used herein, refrigeration relates to establishing
the ambient temperature in the range of 29-60 F., depending on
the requirements of the particular product. Also, when the
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term "produce" is used herein, it is to be understood to apply
to any of the fresh fruits and vegetables, examples of which
are bell peppers, cauliflower, mushrooms, grapes and blueberries.
DESCRIPTION OF THE WORKING EXAMPLES
Example 1: Cauliflo~er Storage
A pallet was stacked with ten (10) corrugated
fibreboard boxes of cauliflower with 16 heads per box, and then
stored in a sealed container having its internal temperature
- maintained at approximately 40 F. The container was cha~ged
with an artificial atmosphere consisting of approximately 2O2%
carbon dioxide, 1.8~ oxygen, 6.0% carbon monoxide and the
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remainder gaseous nitrogen. The cauliflower was kept in this
special atmosphere and at the stated temperature for a period
of six (6) days, at the end of which time the boxes were opened
and the cauliflower removed.
On examination, the cauliflower at the end of the
test period was found to contain some yellow patches indicating
discoloration to curd and/or jacket leaves, wh~ch averaged one
cauliflower head per carton. Some riciness was evident,
averaging about one head every other carton. No heads were
found to be undersized and the overall appearance was
satisfactory.
Thirty other boxes of cauliflower were stacked, as a
control, in a similar manner on a pallet and maintained at 40~ F.
in atmospheric oxygen for the same period of time as the ahove
test cartons of cauliflower. At the conclusion of the storage,
the control cauliflower was found to exhibit yellow
discoloration ranging from patches to entire heads, w'nich
averaged three to four heads per box. Riciness averaged two
heads per box and substantial bacterial soft rot was found on
an average of one head every other box. Overall appearance was
at best borderline for commercial accep~ability.
,
~xample 2: Cauliflower Storage
Thirty six (36) corrugated cardboard boxes having
twel~e (12) cauiiflower heads per box were sealed in four and
five mil plastic bags, each bag containing 10 pounds of lime.
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Aftex sealing, the bags were flushed with carbon monoxide gas
until there was a residual of about 15% remaining. Carbon
dioxide was then added until it formed approximately 10~ of the
. composition which left 12~-13% oxygen and the rest nitrogen.
On conclusion of the test, the four mil bags had
maintained the carbon dioxide at about 5~, oxygen at 5~ and no
carbon monoxide was detectable after six days. In the five mil
bags, the levels of oxygen soon bec~me very low, and a further
10 pound quantity of lime was added after four days to reduce
the carbon dioxide level.
After a total of seven days holding period, only
slight differences could be detected in the bagged cauliflower
having the indicated artificial atmosphere over eiyht similarly
packed boxes of cauliflower in a control atmosphere of normal
atmospheric air. The curd was more compact in modified
atmospheres and the green leaf tissue had a slightly better
color. No significant floret mold developed in any of the bags.
All of the bag samples were then broken open and
allowed to remain in the air for an additional four days with
the temperature held at approximately 60 F. Dramatic ~ -
differences were then detected between those samples of
cauliflower which had been maintained in the artificial
at sphere and those in the air control. Specifically, floret
m~ld was significantly more severe in the air control
cauliflower and, as well, the leafy tissue was very ye~low as
compared to a fresh green color of the artifical atmosphere - r
~tored cauliflower.
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Example 3: Cauliflower St~
Cauliflower was stored in plastic bags and in sealed
barrels at approximately 38 F. for a total of 17 days.
Artificial atmospheres were provided in the various bags and
barrels of the following compositions:
CO CO2 O N2
Bag 1 & Barrel 1 10%-20% 0% 5~ Remainder
Bag 2 ~ Barrel 2 10%-20% 5~ 5% Remainder
Barrel 3 0% ~ 5% 5% Remainder
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At ~he end of 17 days storage, all of the leafy
cauliflower parts held in 5% carbon dioxide atmospheres had a
fresh green color. Significant yellowing of the green leafy
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parts was evident in an air control sample and in those stored
in artificial atmospheres without carbon dioxide. All of the
cauliflower samples treated with carbon monoxide were free of
mold growth on the flower parts. Where carbon monoxide was not
used, but with 5% carbon dioxide, mold growth was significant
and differed little from air control.
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At the conclusion of storage, all of the cauliflower
samples were cooked and tasted. No off color or off flavor was
detected. It was concluded from this example that floret
molding was particularly inhibited by carbon monoxide in the
presence of either/or both elevated carbon dioxide and/or
reduced oxygen.
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Example 4: Bell Pe~per Stora~e
Six boxes of washed and waxed bell peppers were
obtained, four boxes of which were placed in barrels, sealed to
include an artificial atmosphere. The two remaining boxes were ~ -
located in unsealed barrels exposed to ambient atmosphere. All
of the barrels were maintained at 45% F.
Barrel 1 contained an atmosphere of 10~-20% carbon
dioxide, 3%-4% oxygen, 10~ carbon monoxide and the remainder
nitrogen. Barrel 2 had the same composition of artificial
atmosphere as barrel 1, except that it had no carbon monoxide -~
component. Barrel 3 was provided with artificial atmosphere
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of 2%-4% carbon dioxide, 5%-7% oxygen, 10~ carbon monoxide, and
the remainder nitrogen. Barrel 4 had th~ same artificial -
atmosphere as barrel 3 except that there was no-carbon monoxide
present.
After twelve days of storage under the prescribed
conditions and with the prescribed atmospheres, the peppers in
barrel 3 had a field fresh appearance witn no indication of '~r
surface mold, and only two individual peppers showed any
indication of soft rot. The peppers in barrel 4 did show surface
mold and seventeen (17) indicated soft~rot, with their general
appearance all being diminished somewhat by the presence of
black stem ends. Similarly, the air control samples had a
relatively high numher with soft rot, surface mold was - ~-
substantially in evidence and most had black stem ends.
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Aftex a total of sixteen days of storage, the pcppers
in barrel 1 were asain examined and found to have a ield fresh
appearance with no surface mold present at all, although two
peppers did show evidence of soft rot. Barrel 2 had three
peppers with soft rot, substantial surface mold was present, and
an off flavor condition. The air control samples included 13
and 17 peppers, respectively, with soft rot, surface mold was
clearly in evidence and many had black stem ends.
It is concluded from this example that carbon monoxide
enhanced the appearance of the peppers and inhibited fungus
growth.
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-Example 5: ushroom Storage
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Four open boxes of mushrooms were placed in three
different barrels and sealed with the following artificial
atmospheres:
. CO C2 N2
Barrel 1 20% , 5% 3% Remainder
Barrel 2 15~ 15% 10% Remainder
Barrel 3 10~ 15~ 20~ Remainder
In addition, four boxes were maintained in atmospheric air as a
.
control.
None of the mushrooms experienced any marked weight
loss during the test, either those in the control air storage
or in the artificial atmospheres, with overall weight loss being
only about 1% more in air storage than in the artificial
atmospheres.
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At the end of 14 days of storage, with the temperature
maintained throughout at approximately 33-34 F. for all
samples, the mushrooms in barrel 1 were only slightly better in
appearance than the air control mushrooms. It is concluded from
S this that a significant oxygen level should be maintained for
successful mushroom storage.
The mushrooms in barrel 2 at the conclusion of the
14 day test had a good external appearance with some slight
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internal discoloration of the cap and stem tissue, which was
concluded to-be a result of growing conditions rather than .
produced during stoFage.
Barrel 3 had the best overall external and internal
appearance at the conclusion of the test. The mushrooms had a
fresh smell, only very slight external discoloration and no `~
internal discoloration of the cap tissue. The stem tissue did
have some discoloration resulting from growing conditions.
Example 6: Mushroom Storage
~ ushrooms from a different source than those used in
Example 5 were stored at 33-34 F. i~ two separate sealed
containers. The first contained an artificial gaseous
environment of 20% carbon monoxide, 20% oxygen, less than 1
carbon dioxide and the remaihder nitrogen. The atmosphere in
the second barrel consisted of 15% carbon monoxide, 20~ oxygen,
12% carbon dioxide and the remainder nitrogen. A separate
environmental air control barrel was also provided.
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After 14 days of storage~ the mushrooms in the first
barrel had a good external appearance, with some internal
discoloration equal to that experienced in the air control.
Those mushrooms stored in barrel 2 were in nearly
perfect condition after the storage of 14 days. Almost no
internal discoloration could be found in either the caps or the ~ `
stems. - `
Example 7: Grape Storage
A quantity o~ Emperor grapes in open boxes and
previously treated with sulphur dioxide gas were stored in the
following respective modified atmospheres with the temperature
maint~ined at 33-34 F.: ~
CO C2 N2
Container 1 5~ 0%-l~ 5% Remainder
Container 2 0~-1% 5~ Remainder
Container 3 10% 5% 5~ Remainder
Container 4 5% 5~ Remainder
Container 5 10% 5% Remainder
In addition, two boxes of grapes were maintained in
air storage as a control. All of the grapes, whether in the
air storage or the modified atmosphere were stored for ninety-
seven (97) days.
At the conclusion of the storage, those grapes held
in artificial atmospheres including carbon monoxide (containers
1 and 3) were completely free of any mold grow~h. In addition, ~ ;
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these grapes were firm, the taste was normal and the bloom was
good. Stem and pedical tissue was gxeener in those atmospheres
having a lower percentage of carbon dioxide (containers l and 2).
Grapes stored in container 2 had the freshest appearing
stem and pedicel tissue, although there was some accompanying
mold growth. Berry firmness, bloom and taste were good.
The condition of container 4 grapes was comparable to
that of container 3, except that the stem and pedicel tissue
was browner and more shriveled. ~ ~
lQ Grapes from container 5 had an off-flavor and stem ~ -
tissue was very brown and shriveled. No mold growth was
evident.
The air controi grapes experienced severe mold growth
and, also, the stems and pedicels were mar]cedly shriveled and
brown.
Example 8: Blueberry_Storage
Individual pint containers of blueberries of the
"Wolcott" variety were placed in separate desiccators having
ten (lO) different modified atmospheres at 38-40 F. for
- 20 sixteen (16) days, after which they were removed and examined.
The atmospheres used and the results obtained are shown in the
following table:
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TREATMENT % GOOD % RUNNY SOFT % MOLDY ~ BAD
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Air Control
Sample 1 89. a 6.7 4.3 11.0
~ir Control
Sample 2 81.6 13.3 5.1 18.4
1. 5% C2t
10% 291.2 7.1 1.7 8.8
2. 5% CO2,
10~ 2~
15%-25% CO 96.8 2.9 0.3 3.2
3O 5% CO2,
3~ 291.6 7.1 1~3 ~.4
4. 5% CO2,
3% O ,
8%-25~ CO 97.1 2.6 0.3 2.9
5.' 0% CO2,
5~ 289.5 8.0 2.5 10.5
fi. 0% CO2,
5% O~,
10%-20~ CO 95.7 4.0 0.3 4-3
7. 10% CO2,
10% 293.1 6.3 0.6 6.9
8. 10% CO2,
- 10% 2
10%-18% CO 95.7 3.0 1.3 4~3
9. 10% CO2,
3~ 296.3 3.7 -0- 3.7
10. 10~ C2
3~ 2~
18~-25% CO 97.7 2.3 ` -0- 2.3
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Exc~pt for the No. 5 atmosphere, all the berries were
better than the air control samples. The addition of carbon
monoxide gave improved results in all cases. Shelf-life remained
good through three (3~ days at ambient temperature with no off-
flavor, grittiness or other defect detected.
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SUPPL~ENTAR~ D~$CLOSURE
It has now been found that the compositlon of thepreservative atmosphere disclosed in the Principal Disclosure for
preventing the growth of harmful fungi during storage of fresh fruits
and vegetables can be varied somewhat from that already disclosed and
still be effective for the purpose.
It has now been found that the proportion of carbon
monoxide in a fungistatic amount may be between about 3% and about
25% by volume dependent on the nature o~ the fruit or vegetable, the
variety, the length of time between harvesting of the fruit or
vegetable and the application of an atmosphere according to this
invention, and the kind of fungl involved. Preferably the range is
from about 5% to about 25% by volume.
The amount of oxygen may be an amount less than 21%
by volu~e, broadly in the range of about 1% to about 20% by volume.
The remainder will be nitrogen but some carbon dioxide
may be present for certain fruits and vegetables but its presence is
not always required. The proportion of carbon dioxide may be in amounts
from 0% to about 20% by volume.
The amounts of oxygen and carbon dioxide used ~ary with
the kind and varlety of fruit or vegetable sub~ected to the preservative
modified atmosphere according to the invention. ~--
In addition to the Pruits and vegetables to which ~-
reference is specifically made in the Principal Disclosure, other
fruits and vegetables to whlch the ~nvention is applicable are tomatoes,
s~uash, pineapples, peaches, papayas, nectarlnes, ~angoes, melons, egg-
plant, cabbage, avocados, lettuce, apples, pears, apricots, cherries,
potatoes, sweet potatoes and onions.
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The followln~ table shows broad and more preferred
ranges of carbon dioxide, oxygen and carbon monoxide for use with the
kind of fruit or vegetable shown.
FRUIT orBroad Ranges More Preferred Ranges
VegetablePercent by VolumePercent by Volu~e
C2 2 CO N2 C2 2 CO N2
Bell Pepper1-10 5-20 3-25BALANCE 2-7 5-105-15 BALANCE
Cauliflower1-10 3-20 3-25BALANCE 3-6 5-105-15 B~LANCE
Mushroom 3~20 3-20 3-25BALANCE 5-10 10-1510-20 BALANCE
Grape 0-15 2-15 3-25BALANCE 0-10 5-lO10-20 BALANCE
Blueberry 1-15 2-10 3-25BALANCE 5-10 3-55-15 BAI.ANCE
Tomato 0-7 3-10 3-25BALANCE 0-5 4-85-l5 BALANCE
Squash 3-15 2-10 3-25BALANCE 5-10 3-85-15 BALANCE
Pineapple 1-15 2-15 3-25BALANCE 5-10 5-105-15 BALANCE
Peach 1-lO 2-10 3-25BALANCE 3-6 3-6.5-15 BALANCE
Papaya 2-10 2-10 3-25BALANCE 4-8 3-85-15 BALANCE
Nectarine 1-10 2-10 3-25BALANCE 3-6 3-65-15 BALANCE
Mango 2-10 2-lO 3-25BALANCE 4-8 4-85-15 BALANCE
Melon 2-20 3-15 3-25BALANCE10-15 5-105-15 BALANCE
Eggplant 0-8 2-10 3-25BALANCE 0-3 4-85-15 BALANCE
Green Beans 2-10 2-10 3-25 BALANCE 3-6 3-6 5-15 BALANCE
Apples 1-10 1-10 3-25BALANCE 2-8 1-45-15 BALANCE
Pears 0-8 2-8 3-25BALANCE 1-5 1-35-15 BALANCR
Apricots 1-8 2-8 3-25BALANCE 2~-5 2-55-15 BALANCE
Cherrie~ 3-20 2-15 3-25BALANCE 5-15 3-105-15 BALANCE
Cabbage 1-10 2-10 3-25BALANCE 3-6 3-65-15 BALANCE
Avocado 3-15 2~10 3-25BALANCE 5-10 3 65-15 BALANCE
Lettuce 0-5 2 15. 3-25BALANCE 0-3 5-105-15 BALANCE
Potato 5-20 3-10 3-25BALANCE 5-10 4-85-15 B~LANCE
Onion 4-15 1-7 3-25BALANCE 5-10 2-55-15 BALANCE
Sweet Potato 3-5 5-7 3-25 BALANCE 2-7 4-8 5-15 BALANCE
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Not all concentrations oP these gases are effecti~e
or equally efective on each and every kind and variety of fruit and
vegetable. At certain temperatures and with certain m~xtures of gases,
physiological or pathogical damage to certaln Pruits and vegetables
may occur, even though fungi growth is inhibited. Such conditions may
readily be determined and then avoided.
The Pollowing additional examples illustrate further
the scope and content of this invention. In the examples, all per-
centages are percentages by volume unless the contrary is expressly
stated
Example 9: Avocado Storage -~
Two groups of 24 avocados each were placed in separate
containers. The atmasphere in the first container was modified to r~
contain initially a preservative atmosphere lncludlng about 10% carbon
dioxide, about 8% carbon monoxide, about 3% oxygen, the balance all
substantially molecular nitrogen. The atmosphere in the second
container was alr. The temperature inside each container was modified
to and maintained at 55F. Por 16 days. During tbis time, the atmos-
phere in the first contalner was monitored, and ad~ustments were made
to maintain the gas concentration close to the starting concentration.
At the end o~ the storage period, avocados held in the
second container were soPt, ripe and had slight mold growth on their
stem buttons. Avocados held in the first container were hard, green
and free of mold growth. After these observations were made, the
avocados from the first container were held in air at about 70-75F.
for one day, and then at 45F. in Por another day. Avocados that had
been held in the first container were slightly so~t. About half were
still green, the other half were purple-brown in color, indicative oP
partial ripen~ng.
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Neither the avocados held in air nor the avocados held
in preservative atmosphere developed any chilllng symptoms or decayO
Thls example shows that carbon monoxide is an effectlve fungistat on
avocados when used in combinatlon wlth carbon dioxide and oxygen.
Example 10: C age Storage
Two groups of cabbage heads, each including twelve
heads, were placed in separate containers. The atmosphere in the first
container was modifled to contain initially about 5% carbon dioxide,
about 5% carbon monoxlde, and about 5% oxygen. The atmosphere in the ~;~
second container was air throughout the test. The temperature within
each container was modified to and maintained at 42 F. for three weeks.
During this time, the atmosphere in the ~lrst container was monitored,
and adjustments were made to maintain the gas concentrations close to
the starting concentrations.
At the end of this period, the cabbages held in air had ~- ~
turned substantially completely yellow, and ~old growth was visible on ~ ~ -
the wrapper leaves. Cabbages held in the preservative atmosphere were
in good condition. The lea~es had not yellowed and little mold growth
was visible.
The improvement that carbon monoxide produced was
particularly striking because the quality of the cabbage at the outset
of the test was poor; cabbages then had severe leaf spotting on both
wrapper and cap lea~es.
~xample ll: ~gplant Storage ;~
Five groups of 18 eggplants each were placed in separate
containers. In four of the containers, the atmosphere was modifled to
contain initially the following:
Container 1: About 1% - 3% carbon dioxide, about 5% oxygen, about 10%
- carbon monoxide, and the balance substantially all molecular nitrogen.
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Container 2: ~bout 7% carbon dloxide, about 5% oxygen, about 1070 carbon
monoxide, and the halance substantially all molecular nitrogen.
Container 3: About 1% - 3% carbon dioxide, about 5% oxygen, and the
balance substantlally all molecular nitrogen.
Container 4: About 7% carbon dioxide, about 5% oxygen, and the balance
substantially all molecular nitrogen.
The atmosphere in contalner 5 was air throughout the
test. The temperatu~e in each o~ the containers was ad~usted to and
maintained at 45 ~. for two weeks. During this tlme, the atmospheres
in the flrst four containers were monitored and ad~ustments were made
to maintain the gas concentrations close to the starting concentrations.
After the two week period, the eggplant held in air
had poor color, severely molded calyxes, and some pitted surfaces,
indicating that ~lternaria rot had begun to develop.
By contrast, eggplant held in containers 1 and 2 retained
good green color in the calyxes, had little or no decay, and retained
a fresh appearance. Eggplant held in container 1 appeared slightly
better than the eggplant held in container 2
~ggplant held in containers 3 and 4 were in poor
condition. Calyxes on these eggplant had as much mold as eggplant held
in air ? and some scaldlng of eggplant surfaces had also occurred.
Example 12: Lettuce Storage
Three groups o~ lceberg lettuce, each containlng 24
heads, were placed ln separate containers. The atmosphere in the first
container was modified to contain initially about 10% oxygen, about 9%
carbon monoxide, and the balance substantlally all molecular nitrogen.
The atmosphere in the second was modi~ied to contain initially ~bout ~-
10% oxygen, about 15% carbon monoxide, and the balance substantially
all molecular nltrogen. The atmosphere in the third contained air
throughout the test. The temperature ln each container was maintained
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at about 34F. ~or 19 da~s. Dur~ng the test, the atmosphere in con-
tainers 1 and 2 was monitored, and adJustments were made to maintain
the gas concentrations close to the starting concentrations.
At the end of the l9-day perlod, half of the heads were
moved and inspected lmmediately, and the other half were held at about
70 - 75 F. in air ~or two days and then inspected. The results were
as follows: ;~
After 19 days, three of the 12 heads held in air
exhibited Botrytis rot; none of the 24 lettuce heads held in the carbon
monoxide-containing atmospheres showed any. Forty-eight hours later, ;
nine of the 12 lettuce heads held in air exhibited Botrytis rot; none
of the remaining lettuce heads held in the carbon monoxide containing- ~
atmospheres exhibited any such rot. These results show that carbon ~ ~ -
monoxide effectively controls fungi growth that otherwise causes
severe damage to lettuce.
Example 13: Lettuce Storage
Two groups o~ lceberg lettuce, each containing 60 heads, ~
were placed in separate containers. The atmosphere in the first ~ ;
container was modified to produce an atmosphere initially containing
about 8% oxygen, about 20% carbon monoxide, and the balance substantially `
all molecular nitrogen. The second container held air throughout the
test. The temperature ln each contalner was lowered to and maintained
at about 33 - 34F. for two weeks. During that time, the atmosphere
in the first container varied from about 20% carbon monoxide to about
7%, and the oxygen, from about 8% to about 10%.
'` ~t the end of the two week period, none of the lettuce
held in the first container exhiblted Botrytis, but two of the lettuce
heads held in air did. Moreover9 only 12 of theheads held in the first
container exhlbited developing soft rot; 22 from the air control did.
Severity of decay was considerably lower for lettuce hsads treated with
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carbon monoxide than ~or lettuce heads held in air without carbon
monoxide. Again, carbon monoxide appeared to inhibit substantially the
growth of Botrytis fungi and bacterial soft rot on lettuce.
Example 14: Honeydew Melon Storage
Five groups of ~ive honeydew melons each were placed
in separate containers. The atmosphere ln four of the containers was
modified; the atmosphere in the ~i~th was air throughout the test.
The modified atmospheres were as follows:
Container 1: Zero to about 2% carbon dioxide, about 5% oxygen, about
10% - 15% carbon monoxide, and the balance substantially all molecular
nitrogen.
Container 2: About 5% carbon dioxide, about 5% ox~gen, about 10% - 15%
carbon monoxlde, and the balance substantlally all molecular nitrogen.
Container 3: About 10% carbon dioxide, about 5% oxygen, about lO% - 15%
carbon monoxide, and the balance substantially all molecular nitrogen.
Container 4: ~bout 15% carbon dioxide, about 5% oxygen, about 10% -
15% rarbon monoxide, and the balance substantially all molecular
nitrogen.
The atmosphere in each container was maintained at about 50 F. for
three weeks. During this time, the atmosphere in each of the first
four containers was monitored, and ad~ustments were made to maintain
the gas concentration close to the starting concentrations.
The containers were opened after the three week period,
and the melons inspected. Those in the modified atmosphere treatment
were free from rot and mold growth. Three of the five melons from
the air control exhibited decay, mold growth or both.
After holding the melons ~rom each of the containers
at about 70 - 75F. in air ~or ~our days, four of the ~ive melons held
exhibited decay, but none of the melons held in modified atmosphere did.
No rind blemishes developed in melons held in modified atmospheres,
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and the taste and aroma of all melons, including those held ln air,
was normal.
Example 15: Cantaloupe Storage
Six groups o~ 16 cantaloupes each were placed in
separate containers. The atmospheres in ~ive o the containers were
modified to contain the following:
Container 1: Zero - about 2% carbon dioxlde, about 5% oxygen,
10% - 15~ carbon monoxide, and the balance substantially all molecular
nitrogen.
Container 2: About 5% carbon dioxide, about 5% oxygen, about 10% - 15%
carbon monoxide, and the balance substantially all molecular nitrogen.-
Container 3: ~bout 10% carbon dioxide, about 5% oxygen, about 10% -
15% carbon monoxide, and the balance substantially all molecular
nitrogen. ~;
Container 4: About 15% carbon dioxide, about 5% oxygen, about 10%
15% carbon monoxide, and the balance substantially all molecular
nitrogen.
Container 5: About 0 - 5% carbon dioxide, about 21% ~ 4% oxygen,
about 10% - 15% carbon monoxide~ and the balance substantially all
molecular nitrogen.
The sixth container held air throughout the test. The
temperature in each container was lowered to and maintained at about
50 F. for three weeks. During the three weeks, the gas concentrations
in containers 1 through 5 were monitored, and adjustments were made
to maintain the gas concentrations close to the starting concentratlons.
Ho~ever, in container 5, the oxygen concentration was permitted to
decrease from 21% at the outset to 4% at the end o~ the three week
period.
At the end o~ the three weeks, the containers were
opened and the cantaloupes exalQined. All melons exhibited some mold and
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decay, but the carbon monoxide treated melons exhibited substantially
less decay than cantaloupes held in air. Higher concentrations of
carbon dioxlde in comblnatlon wlth carbon monoxide enhanced inhibition
of the fungi.
Example 16: Nectarine Storage
~our groups of nectarlnes, each containing from 25 to
30 fruit, were placed ln sepa~ate contalners. The atmosphere in three
of the containers was modified to contaln initially the following con-
centratlons of gases:
Container 1: ~bout 12% carbon dioxlde, about 3% oxygen, and the balance
substantially all molecular nitrogen.
Container 2: About 12% carbon monoxide, about 10% oxygen, and the ~ ;
balance substantially all molecular nitrogen.
Container 3: About 7% carbon dioxide, about 7% oxygen, about 10%
carbon monoxide, and the balance substantlally all molecular nitrogen.
The fourth container held air throughout the test.
The temperature oR each container was lowered to 32~. initially, but
rose to 50~. for at least part of the test period. Dur-Lng the three
week period, the gas concentrations in each of the first three
containers were monitored and ad~ustments were made to maintain the
concentrations at or near the starting concentration.
~fter three weeks, the containers were opened and the
fruit inspected. Of the 28 fruit in container 1, 8 exhibited some brown
rot and some off-flavor. Of the 25 ruit container 2, none exhibited
brown rot, but some were off-flavor. Of the 25 fruit in container 3,
none exhlbited brown rot, and flavor was acceptable. Of the 31 ~ruit
held in air, 12 exhibited brown rot, and again flavor was acceptable.
Carbon monoxide inhibited development of brown rot
fungi without any detrimental impact on flavor. ~oreover, where carbon
monoxide was present, carbon dioxide could be maintained at lower levels,
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insuring preservatlon o~ good flavor.
Example 17: Papaya Storage
Two groups of papaya, one containlng 14 fruit, the
other 16 fruit, were placed ln separate contalners. The atmosphere
in the first container was modified to contain initially an atmosphere
of about 10~ carbon dioxide, about 3% oxygen, about 10% carbon monoxide,
and the balance substantial all molecular nltrogen. The atmosphere in
the second container was air throughout the test. The temperature in
each container was modl~led to, and held at 55~. ~or 10 days. During
the 10 days, the atmosphere in the first container was monitored, and
ad~ustments made to maintain gas concentrations at or near the initial
concentrations.
~t the end of 10 days, papayas held in air were riper
than those held in the modlfled atmosphere. All ~ruit was~held another
four days at about 70-75~. in air to observe ripening and shelf life. ~ `
At the end of four days, fruit held in modified atmosphere was still
not nearly as ripe as the fruit held ln air throughout.
None o~ the fruit developed any ~nthracnose rot, but
4 of the 16 fruit held in alr developed stem end rot. Only 1 o~ the
fruit held in the modif~ed atmosphere exhibited any stem end rot.
Taste and aroma of all fruit was normal, indicating that carbon monoxide
had no deleterious effect on flavor.
Example 18: Peach Storage
Three groups of peaches of the Summerset variety, 100
fruit ln each group, were placed in separate containers. The atmosphere ;~
in the fruit container was modlfied to contain initially about 3% carbon
dioxide, about 4% oxygen, about 10% carbon monoxide, and the balance
substantially all molecular nitrogen. The atmosphere in the second `
container was modi~ied to contain about 5% carbon dioxide, about 5
oxygen, about 10% carbon monoxlde, and the balance substantially all
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molecular nitrogen. The third container held air throughout the test.
The temperature in each container was reduced to and held at about
32F. for five weeks. During this time, the gas concentrations in the
first two containers were monitored, and ad~ustments were made to
maintain the gas concentrations at or near the startlng concentrations.
At the end of three weeks, the containers were opened,
and 50 peaches were removed from each of the containers. O~ the 50
peaches removed from the air container, 8 were decayed at mechanically
damaged areas. ~d~ancement of decay was moderate, and mycelial growth
was abundant. Of the 50 peaches ~rom container 2, 5 were decayed at
mechanically damaged areas, but decay was much less advanced than with
peaches held in air, and both mycelial growth and sporulation were
inhibited. Of the 50 peaches held ln container 1, 3 were decayed at
mechanically damaged areas, but again, mycelial growth and sporulation
were inhibited.
The rest of the peaches were held two more weéks in the
containers under the same condi~ions. O~ the lO0 peaches from the two
modified atmosphere containers, only 13 in all (6 ~rom container 1 and
7 from container 2) were decayed at mechanically damaged areas. Of
the 50 peaches from the air control atmosphere, 22 were decayed in
mechanically damaged areas. No mycellal growth or sporulation was
evident on peaches held in modified atmospheres, but such growth and
sporulation was pro~use on peaches held in air. Moreover, peaches held
in modified atmosphere containing the higher concentration of carbon
dioxide had the best texture and taste of the three groups. Peaches
held in the lower concentration of carbon dioxide and the peaches
held in air were drier and much less tasty.
Example 19: _ 1 pepper Storage
~our groups o~ about 100 bell peppers each were placed
in se~arate contalners. In the first container, the atmosphere was
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modi~ied to produce an atmosphere containlng initially about 3% carbon
dloxide, about 5% oxygen, about 25% carbon monoxide, and the balance
substantlally all molecular nitrogen. In the second container, the
atmosphere was alr throughout the test. The temperature in each
container was reduced to and held at about 48 to about 50~. for
23 days. During thls tlme, the oxygen concentr~tion varled ~rom about
5% to about 10%, and the carbon ~onoxlde concentratlon Prom about 25%
to about 10% ln the first container.
At the end of 23 days, the peppers were removed and
observed. Peppers held ln alr had mold growth on all stems, and many
exhlbited severe rottlng. Peppers held ln the modified atmosphere were
Pree of surface mold growth and rots.
In a separate test, a third group of peppers was placed
in a third container, and ~he atmosphere therein modified to contain ;~
initially about 2% carbon dioxide, about 5% oxygen, about 15% carbon
monoxide, and the balance substantlally all molecular nitrogen. The
atmosphere ln the fourth container, into whlch was placed the fourth
group of bell peppers, was air throughout this second test. The
temperature in the thlrd and Pourth contalners was reduced to and ~ ;~
malntained at about 48 to about 50~. throughout a 14 day test perlod. ;~ ; '
ThereaPter, the peppers were removed and observed, and results were ;
comparable to those obtained with the peppers held in containers 1 and
2 for 23 days. ~ ~
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Example 20: Zucchini Squash Sto~age
~ .
Six groups of Zucchini squash, each group containing
:~ :
about 110 to about 120 squash, were placed in separate containers. ~`
The atmospheres in 5 of the containers were modiPied to produce the
Pollowing compositions:
Container 1: About 10% carbon dioxide, about 3% to about 5% oxygen7
and the balance sub~tantlally all molecular nltrogen.
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1~6~6~
Container 2: About 10~ carbon dloxide, about 3% to about 5% oxygen!
about 10% carbon monoxlde, and the balance substantially all molecular
nitrogen.
Container 3: About 5% carbon dioxide, about 3% to about 5% oxygen,
and the balance substantially all molecular nltrogen.
Container 4: About 5% carbon dioxide, about 3% to about 5~ o~ygen,
about 10% carbon monoxide, and the balance substantially all molecular
nitrogen.
Container 5: ~bout 20% oxygen, about 10% carbon monoxide, and the
balance substantially all molecular nitrogen.
The sixth container held air throughout the test. The temperature in
each of the containers was reduced to and maintained at about 45F.
to 47F. for two weeks. During this time, the atmospheres in containers
1 through 4 were monitored, and ad~ustments made to hold the concentra-
tions at or near the starting concentrations. However, in the fifth
container, the oxygen concentration was permitted to decrease naturally
by respiration to about 3% at the end of the test period.
At the end of two weeks, the squash were removed and
inspected. The squash held in air had surEace mold growth on virtually
the entire surface of all the squash. Ten squash held in air exhibited
some decay. Squash held in container 1 had a small quantity of surEace
mold growth; 7 squash were slightly decayed. Squash held in container
2 had no decay and only traces of surface mold growth. Squash held in
container 3 had the most surPace mold growth and the highest number of
decayed squash. The squash from container 4 were not decayed and
exhibited only traces of surface mold growth. Squash held in container
5 had little decay but exhibited substantial mold growth, indicating
that car~on dioxide also has a valua~le role in preserving the life of
this vegetable.
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Example 21: Tom~to Stor~ge
.
Three groups o~ 48 tomatoes each were placed in separate
containers. The atmospheres in the first two containers were modified to
produce the followlng:
Container 1: About 3% to about 5% oxygen, about 5% to about 10%
carbon monoxide, and the balance substantlally all molecular nitrogen.
Container 2: About 3% to about 5% oxygen, and the balance substantially
all molecular nitrogen.
The third container held air throughout the test. The temperature in
each container was seduced to and held at about 50 F. Por 23 days.
During this time, the concentrations of gases in containers 1 and 2
were monltored, and adJustments made to maintain the concentrations
at or near the startlng concentratlons.
~t the end oP 23 days, the tomatoes held in container
1 were free from rot. Tomatoes Prom containers 2 and 3 were severely
rotted. This test proves that carbon monoxide effectlvely inhibits
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the growth of fungi on tomatoes.
Example 22: Tomato Storage ;~
Two groups oP 72 tomatoes each were placed in sepa~ate
containers. Half of each group had a color index of 2-3; the other -~half, 4-5. Atmosphere in container 1 was modiPied to contain initially
about 5% oxygen, about 14% carbon monoxide, and the balance substantially
all ~olecular nitrogen. The atmosphere in container 2 was alr through~
out the test. The temperature ln each container was modified to and
held at about 50F. for two weeks. During that time, the gas con- ~;
centrations in container 1 were monitored and ad~ustments made to ;~ `
maintain the concentrations at or near the starting concentrations. ;
At the end oP two weeks, the tomatoes held in air had ~ ~
all advanced to a color index oP 5. Those lnltlally of lndex 4-5 were ~ -
40% decayed and surface mold growth was present on all stem scars.
_ 26 -
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Those inltlally of color index 2-3 we~e ~bout 20% decayed, and surface
mold growth was present on about 50% o~ the stem scars.
Those tomatoes held in modi~ied atmosphere that
initially had the color lndex 4 5 advanced to color index 5 almost
entirely, and were free of surface mold growth and decay. Those
tomatoes held in modi~ied atmosphere that had an initial color index
of 2-3 were still substantially all at index 2~3, and were also free
of surface mold growth and decay.
Example 23:- Thompson Seedless Grape Storage ~ ;
Four boxes o~ Thompson seedless grapes, each box
containing about 20 pounds o~ grapes, were placed in separate containers.
These grapes had been pseviously treated with sulfur dioxide in order
to control decay. The atmospheres in the flrst three containers were
modified to produce atmospheres initially having the following
compositions:
Container 1: About 10% carbon dioxide, about 5% to about 10% oxygen,
about 10% to about 20% carbon monoxide, and the balance substantially
all molecular nitrogen.
Container 2: About 5% carbon dioxide, about 5% to about 10% oxygen,
about 10% to about 20% carbon monoxide, and the balance substantially
all molecular nltrogen.
Container 3: About 5% to about 10% oxygen, about 10% to about 20% ~ ~ -
carbon monoxide, and the balance substantially all molecular nitrogen.
The atmosphere in the ~ourth container was air throughout the test.
The temperature in each of the containers was modified to, and held
at about 33 to about 34 ~. for 11 weeks. During this time, the gas
concentrations in the first three containers were monitored, and
adjustments made to maintain the concentratlons of each of the gases at
or near the initial concentrations. After four weeks, mold was evident
in alr control grapes. After seven weeks of storage, the air control
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grapes were a solid mass o~ ne~tlng mold. ~ll g~apes held ln ~odlfled
atmospheres were free of rots and mycelial growth at the end of the
11-week period. These results were particul~rly striking because the
ideal storage temperature for grapes is about 30 to about 31 F.
Example 24: Grape Storage
Grapes of two varieties, namely Cabernet Sauvignon and ~
Johannesberg Reisllng, each variety lncluding some grapes of grade one -
Irot free) and grade two (Alternaria fleld rot infected) were divided ~ -
as follows for testing. ~pproximately one pound of grade one grapes
rom each variety was placed in a first container, and approximately ;
one pound of grade two grapes of each variety was placed in a second
container. Approximately the same quantities and comblnations were
placed in third and ourth containers to serve as controls. -
The atmosphere in the first container was modified to
produce a composition including about 5% to about 12% oxygen about
15% to about 20% carbon monoxide, and the balance substantially all ~ ~ -
molecular nitrogen. Thé atmosphere in the second container modified
to produce a composition including about 2% to about 5%-oxygen, about ;~
20% to about 25% carbon monoxide, and the balance substantially all
molecular nitrogen. The second container also included amounts of
carbon dioxide that did not exceed about 1% at any time during the ~est.
The atmosphere in the third and fourth containers was air throughout ~
the test. The temperature in each of the containers was modified to ;
and maintained at about 34 to about 35F. for a 45-day period.
During that time~ the carbon monoxide and oxygen concentrations in the
first two containers fluctuated between the values set forth above,
and adjustments were made to maintain these values within these ranges
throughout the test period.
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At the end of 45 days, the grade 1 grapes from container
1 were free of mold growth. The Alternaria field rot infectlons on
the grade 2 grapes from container 2 had not advanced, indicating that
the rot infections were inhibited. By contrast, the grade 2 grapes
from the air control container 4 were grossly rotted and mycelial
growth was abundant. Mold growth on grade 1 grapes from container 3
was also ob~ectionable though not as severe as that on grade 2 grapes
from container 4.
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