JPS6329972B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for extending the useful life of vegetables, such as lettuce, cabbage, etc., and more particularly to a method for packing vegetables and especially cut vegetables, such as lettuce, cabbage, etc. It relates to a method by which both the normal respiration of vegetables and their resistance to microbial spoilage, which is fatal to their shelf life, are maintained during the storage period. The present invention provides a method for packaging vegetables, such as lettuce, cabbage, etc., in sealable packages having different permeability to oxygen, carbon monoxide, and carbon dioxide. This method is particularly effective on cut vegetables such as cut lettuce, cabbage, etc. These vegetables are
The package is sealed within a package containing an atmosphere comprising an oxygen concentration substantially greater than about 21% by volume and a carbon monoxide concentration of at least about 3% by volume. The remainder of the atmosphere within the package is substantially all molecular nitrogen. The package must have permeability to oxygen, carbon monoxide, and carbon dioxide at least equal to that of low density polyethylene having a thickness not greater than about 2 mils. Such polyethylene typically meets ASTM test method D1434-66.
The permeability to oxygen per 100 square inches per 24 hours is at least about 500 c.c. and the permeability to carbon dioxide per 100 square inches per mil is at least about 1350 c.c. Preferably, the package according to the invention is formed of a sheet material such as high density polyethylene, or low density polyethylene, or polyethylene modified with other materials such as ethylene vinyl acetate or sulurin. Such packaging must be sufficiently strong to withstand damage that may be caused by transportation and shipping, and sufficiently transparent to permit viewing of the condition of the vegetables inside. Also, the permeability to oxygen and carbon dioxide must be high enough to prevent the carbon dioxide content from becoming too high or the internal oxygen concentration from becoming too low. This prevents the development of anaerobic conditions and the formation of slimy or other undesirable substances on the surface of the vegetables, or other undesirable effects such as de-aroma or de-aromatization within the vegetables. These effects are best achieved when the packages and their contents are maintained at temperatures within the ranges described below. Package sizes can range from, for example, individual consumer use on the order of a few ounces or pounds to pallet-sized packages having a capacity of hundreds of pounds. Vegetables to which the novel method according to the invention can be advantageously applied include, for example, celery, green onions, broccoli, cauliflower, parsley, lettuce, cabbage, etc. Particularly advantageous is the application of this method to cut lettuce. Examples of such cut vegetables include shredded or shredded lettuce. These vegetables are preferably stored and shipped at temperatures below 40°, more preferably below 35°, but above the freezing point of the moisture within the vegetables. The preferred temperature range for storage and shipping of these vegetables is from about 29〓 to about 45〓
That's it. At temperatures above 45°, mucus conditions, other microbial deterioration, and undesirable odors and aromas begin to develop in the vegetables, which can spread quickly. The packages used in the method of the invention may be made of high density polyethylene, low density polyethylene, polyethylene blended with ethylene vinyl acetate, polyethylene blended with sulurine, or other thermoplastic materials having the desired permeability properties. Preferably, it is formed of a sheet material of thermoplastic material. Typically, the transmittance of thermoplastic materials decreases proportionally with increasing thickness. Thus, a 1 mil thick sheet of high density polyethylene typically has three times the transmittance of a 3 mil thick sheet made of the same polyethylene. The atmosphere confined within the package cage containing the vegetables must contain an initial concentration of oxygen greater than 21% by volume. Therefore, the atmosphere is
It contains at least about 25% oxygen by volume, and more preferably at least about 40-50% oxygen by volume.
Additionally, the atmosphere should also contain at least about 3% by volume carbon monoxide, and more preferably at least about 3% by volume carbon dioxide.
The remainder of the atmosphere within the package is substantially all molecular nitrogen. After a modified atmosphere is enclosed in the package and vegetables are placed in the package, the oxygen concentration decreases and the carbon dioxide concentration increases due to the respiration effect that the vegetables undergo. Increasing the oxygen within the package prior to sealing the package substantially delays the onset of anaerobic or semi-anaerobic conditions within the package. Proper selection of the permeability of the package will allow for sufficient oxygen diffusion into the package, as well as enough to prevent the concentration of carbon dioxide from becoming much higher than 20-25% by volume. Carbon dioxide can escape from the package. The carbon monoxide initially added to the package is
It suppresses undesirable discoloration that may otherwise occur in vegetables due to increased oxygen concentration within the package. In the absence of the increased oxygen concentration used in this method, this addition of carbon monoxide reduces the oxygen concentration and increases carbon dioxide within the sealed package, thereby improving the aroma and flavor of the vegetables. It is thought that there will be a negative impact on The increased oxygen concentration used in the method of the present invention substantially prevents such undesirable results. However, the method of the present invention extends shelf life by minimizing loss of flavor and aroma and undesirable discoloration, which would be highly unlikely with conventional packaging techniques. That's true. In fact, the prior art's reliance on quasi-anerous packaging resulted in product quality deterioration after a period of storage. As can be seen from the examples described below, vegetables, especially cut vegetables, encapsulated in sealed packages with a modified atmosphere according to the present invention can last longer than if they were not so encapsulated. maintain the desired color, flavor, and appearance. Those vegetables retain their desirable properties even after the package is opened. In the following examples, all gas concentrations are expressed in volume percent unless otherwise specified. EXAMPLE A piece of lettuce is cut into average dimensions of about 1/2 inch, and the lettuce so cut is A.
It was divided into six samples designated B, C, D, E and F. These groups were placed in separate low density polyethylene bags measuring 12 inches by 24 inches and having sidewall thickness of approximately 1.5 mils. These bags have a permeability of 1350 c.c. for carbon dioxide per 100 square inches, 1 mil and 24 hours, and a permeability of 500 c.c. for oxygen per 100 square inches, 1 mil and 24 hours. Sample bag A was sealed and stored at 35°C.
After one day, the oxygen concentration in sample bag A will be approximately 7%.
The carbon dioxide concentration was approximately 5%. After 5 days, the oxygen concentration had dropped to about 4% and the carbon dioxide concentration had risen to about 11%. Thereafter, the carbon dioxide concentration varied between about 10% and about 15%, and the oxygen concentration varied between about 2% and 5%. In sample F, the oxygen concentration is about 5% after 1 day, about 2% after 3 days, and the carbon dioxide concentration is about 5% after 1 day.
%, about 10% after 2 days, and about 15% after 4 days. After that, the oxygen concentration remained below about 4%, and the carbon dioxide concentration varied between about 15% and 17%. The atmosphere within the sample B bag was initially modified to be approximately 12% oxygen, approximately 27% carbon monoxide, and the balance substantially all nitrogen. This bag was sealed and stored at 35㎓. After one day the oxygen concentration was about 4% and after six days it was about 1%. The carbon monoxide concentration in this bag decreased to about 25% in 1 day, to about 20% in 5 days, and to about 15% in 7 days.
%, decreased to about 10% in 15 days, and
It dropped to about 5% in 17 days. Carbon dioxide concentration is 1
Up to about 5% in 5 days, about 10% in 5 days, about 15% in 6 days
%, and rose to about 20% in 11 days. Sample C contains approximately 24% carbon monoxide and approximately 21%
of oxygen and the balance being substantially all nitrogen. 35〓
When stored in
It decreased to about 10% in 1 day, to about 1% in 6 days, and remained unchanged for the next 13 days. Carbon monoxide concentration is 2
Up to about 20% in 1 day, about 15% in 8 days, about 10% in 15 days
%, dropped to about 5% in 17 days, and then to zero after 5 days. Carbon dioxide concentration decreases to approximately 5% in 1 day, approximately 10% in 5 days, and approximately 15% in 7 days.
and rose to about 20% in 13 days. After that, it remained at about 20% for the next 7 days. Sample D initially has an oxygen concentration of about 12%,
The package is sealed with an atmosphere consisting of a carbon monoxide concentration of approximately 17%, the balance being substantially all nitrogen, and is exposed to 40
〓 was maintained. By the third day, the oxygen concentration had dropped to near zero percent and remained unchanged for the remainder of the test period. Carbon monoxide concentration is 3
It decreased to about 15% in 1 day, to about 10% in 5 days, and remained unchanged for 13 days before gradually decreasing to zero by the end of the test period. The carbon dioxide concentration gradually decreases to about 5% in 1 day, to 10% in 2 days, to about 15% in 4 days, to about 20% in 9 days, and to about 17% for 14 days. It rose to about 23%. Sample E was maintained at 40°C for the entire duration of the test and was initially exposed to a modified atmosphere consisting of approximately 18% oxygen, approximately 19% carbon monoxide, and the balance being substantially all nitrogen. Enclosed. The oxygen concentration dropped to about 10% in one day and to about 1% in three days.
Carbon monoxide concentration reaches about 15% in 2 days and about 10% in 5 days.
%, dropped to about 5% in 10 days, and almost zero in 20 days. The carbon dioxide concentration was almost zero at first, but it rose to over 10% in two days, and about 15% in three days.
%, rose to about 20% in 7 days, and rose to about 25% in 11 days. In this example, carbon dioxide concentrations rose more quickly and generally remained at higher levels when cut lettuce was packaged and stored at 40° than when it was stored at 35°. . Introducing carbon monoxide at concentrations higher than about 5% by volume also increased the rate of increase in carbon dioxide concentration. In this example, samples A and F had as good post-storage quality as samples C and E. Samples A, C,
E and F all outperformed samples B and D, which was cut off when the carbon monoxide concentration was initially increased without accompanying increase in oxygen concentration in the sealed package. It was shown to be harmful to lettuce. EXAMPLE In this example, six samples of commercially available shredded lettuce having dimensions of approximately 1/4 inch were divided into two groups. The first group included samples A and B. Each sample is
It was placed in a low density polyethylene bag measuring 12 x 24 inches and having a wall thickness of approximately 3 mils. These polyethylene bags are 100 square inches, 1 mil and 24
Permeability to carbon dioxide per hour is 1350c.c.
and has an oxygen permeability of 500 c.c. per 100 square inches, 1 mil and 24 hours. Each sample bag A and B was sealed without denaturing the atmosphere within them. The second group is samples C, D, E and F
It contained. Samples C, D, E, and F were each packaged in a low density polyethylene bag measuring 12 x 24 inches and having a wall thickness of approximately 1.5 mils. These polyethylene bags are 100 square inches,
100 square inches, 1 mil and 24 hour carbon dioxide permeability of 1350 c.c.
The permeability to oxygen per 24 hours is 500c.c.
The atmosphere in sample bags C, D, E, and F was changed to the following initial composition, and then sealed. C: about 26% oxygen, about 17% carbon monoxide, the balance is substantially all nitrogen D: about 11% oxygen, about 23% carbon monoxide, the balance is substantially all nitrogen E: about 18% oxygen, carbon monoxide About 23% carbon oxide, balance substantially all nitrogen F: About 8% oxygen, about 26% carbon monoxide, balance substantially all nitrogen Samples B, C and D were maintained at 35〓 throughout the test. In the atmosphere surrounding Samples A and B, the oxygen concentration dropped below 3% within two days, but remained near that level throughout the test period. Carbon dioxide decreases to about 5% in 1 day and about 10% in 2 days.
%, up to about 15% in 5 days, up to about 20% in 14 days,
It rose to about 25% in 16 days. After 14 days of storage at 35°C, samples A and B
has deteriorated considerably. In the case of sample bag C, the oxygen concentration decreased to about 5% in 2 days, rose slightly on the 6th day, and
By the 12th day, it gradually decreased to almost zero percent. Carbon monoxide concentration decreased to about 15% or less in 4 days.
It dropped to less than 10% in 9 days, to less than 5% in 15 days, and to zero in 18 days. The carbon dioxide concentration is 2
It rose to about 10% by day one and then stayed between about 10% and 15% for the entire test period. In the case of sample bag D, the oxygen concentration dropped to below about 5% in two days, dropped to nearly zero by day five, and remained unchanged for the remainder of the test period. Carbon monoxide concentration reaches approximately 20% in one day.
It dropped to about 15% on the 5th, to about 10% on the 15th, to about 5% on the 19th, and to almost zero on the 24th. In the case of sample bag E, the oxygen concentration decreases approximately in 3 days.
15% or less, about 10% or less in 4 days, about 5% in 7 days
It then dropped to almost zero in eight days. The carbon monoxide concentration will be below 20% by the third day, below 15% by the fourth day, below 10% by the 12th day, and below 17% by the 12th day.
By day 2 it had dropped to less than 5% and by day 23 it had dropped to almost zero. The carbon dioxide concentration rose to over 10% by the 6th day, and over 15% by the 10th day,
After that, the rate of increase became slower than those, rising to about 19% by the 26th day. In sample bag F, the oxygen concentration decreased to about 5% or less in one day, to almost zero in four days, and then
By the 12th day it rose again to almost 5% and another 20
By day one it had dropped again to almost zero. Carbon dioxide concentrations rose to over 10% by the fourth day, to 15% by the eighth day, then decreased slightly until the 12th day, and rose again to about 20% by the 18th day. On the other hand, the carbon monoxide concentration gradually decreases to below about 20% by the fourth day, below about 15% by the seventh day, below about 10% by the ninth day, and by the 16th day. It decreased to about 5% or less. Lettuce samples C and E treated according to the invention remained fresh for 32 days and 21 days, respectively. However, lettuce samples D and F exhibited decline after 19 and 14 days, respectively, indicating that if the concentration of carbon monoxide in the lettuce cage is high, the concentration of oxygen must also be increased. I found out something. Introducing only carbon monoxide at a concentration above 5% prior to sealing the package can be very harmful, as it hastens the onset of anaerobic effects in the case of samples D and F. Ta. Example In this example, one lettuce (variety Salinas)
was cut into approximately 1/2 inch pieces and divided into eight equal weight samples A-H. Samples A, C, E, and G were each packaged in low density polyethylene bags measuring 12 x 24 inches and having a wall thickness of approximately 1.5 mils. Those polyethylene bags
The permeability to carbon dioxide per 100 square inches, 1 mil and 24 hours is 1350 c.c., and the permeability to oxygen per 100 square inches, 1 mil and 24 hours is 500 c.c. Samples B, D, F and H
Each has dimensions of 12 x 24 inches with wall thickness
Packed inside a 1.5 mil high density polyethylene plus Sururin bag. Those polyethylene bags
The permeability to carbon dioxide per 100 square inches, 1 mil and 24 hours is 1350 c.c., and the permeability to oxygen per 100 square inches, 1 mil and 24 hours is 500 c.c. For sample bags A and B, the atmosphere was initially about 43% and 37% oxygen and about 14% oxygen, respectively.
and about 13% carbon monoxide, with the balance being substantially all nitrogen. After sealing, sample bags A and B were stored for 14 days at 38㎓. During the storage period, the oxygen concentration drops from the initial level to about 25% by day 2 for sample B and by day 1 for sample A.
%, by the third day in case B, by the second day in case A, to about 20% or less, and in each case to about 15% or less by the fourth day. ,
decreases to about 10% or less after the 6th day in each case, and about 5% by the 10th day in each case
gradually decreased to. The carbon dioxide concentration increases by about 10% on day 5 in case B, on day 6 in case C, and about 13%-14% in each case.
increased to its maximum value, but never exceeded 15% at any point. The carbon monoxide concentration drops to about 10% or less on the first day, to about 5% or less by the second day, to about 2% or less by the third day,
Thereafter, it decreased to near zero by day 6 for both A and B. Even after 14 days of storage, the lettuce from both A and B had a good appearance, no discoloration, and a good taste. In sample bags C and B, the atmosphere initially consisted of about 38% and about 45% oxygen, respectively, with the balance being substantially all nitrogen. 38
After 2 days of storage at 1000 ml, the concentration of oxygen decreased to less than 20% in both samples, and after about 3 days it decreased to less than about 15%. In the case of each sample, the oxygen concentration stabilized after about 6 days of storage, remained approximately constant for sample D thereafter, and decreased to about 15% for sample C over the next 8 days. It rose to %. The concentration of carbon dioxide increased from almost zero to about 5% in 2 days and to about 10% in 6 days in both cases, and remained unchanged in sample D, but remained unchanged in sample C. decreased to approximately 2% by day 14. After 14 days of storage, in the case of both Samples C and D, the lettuce had a good taste, but both had a noticeable pink discoloration that made them commercially unattractive. Sample bags E and F each have approximately 15% initially
of oxygen, approximately 11% carbon monoxide, and the balance substantially all nitrogen. In each case, by the second day, oxygen levels had fallen to about 6% and carbon monoxide to about 5%. Thereafter, the concentration of carbon monoxide in both samples was approximately 1 by the time they were stored for 10 days.
% gradually decreased. In each case the oxygen concentration decreased to about 4% and about 5%, respectively, and rose to over 5% after the 9th day. In each case, the carbon dioxide concentration rises to about 5% or more by day 2, about 10% or more by day 5, then stabilizes and declines slightly to just below 10% by day 14. Although the lettuces from Samples E and F had a good appearance after 14 days, both had significant deterioration in taste and aroma, indicating that the concentration of oxygen in the atmosphere was not high enough to increase the concentration of monoxide before sealing. This shows that increasing the concentration of carbon leads to unfavorable results. The atmosphere within sample bags G and H was not denatured before being sealed. After 2 days of storage, the oxygen concentration in each sample bag decreased to about 10% or less;
After six days, it dropped to less than about 5% and rose again to about 12% by the end of the 14-day period. The concentration of carbon dioxide in each sample increases from an initial near zero to more than 5% by day 4, to more than 10% by day 6, after which it stabilizes, but by day 14 it increases to about 5%. %. At the end of the 14 day storage period, Samples G and H ranged from slight to marked in discoloration and intermediate in deflavoring and deodorization. After 14 days, all eight sample packages were opened and placed in a 55° room to simulate retail conditions. After two days, lettuce from all eight samples exhibited a pink discoloration, with samples C, D, G, and H exhibiting particularly marked decline. After 6 days at 55〓, all the lettuce samples exhibited some degree of decline. In this example, samples A and B, which were initially treated with high oxygen and carbon monoxide concentrations in accordance with the present invention, were superior. EXAMPLE In this example, 20 equal weight samples of lettuce cut into 1/8 inch pieces are
divided into 10 groups represented by 1/
The other four samples consisted of lettuce cut into 2-inch pieces with purple cabbage and ginseng.
They were divided into two groups, denoted by and L. Each of these 12 groups is e.g.
Two identical samples were included, designated with subscripts 1 and 2, such as A1 and A2. Samples A1, A2, B1, and B2 were placed in separate sealable bags made of low density polyethylene mixed with 8% ethylene vinyl acetate and measuring 12 x 24 inches and having a wall thickness of approximately 2 mils. Rare, 38
It was stored in 〓. These bags are 100 square inches,
It has a permeability to carbon dioxide of 1350 c.c. per mil and 24 hours and a permeability to oxygen of 100 square inches and 500 c.c. per mil and 24 hours. These EVA (ethylene vinyl acetate)
It is said that the strength and permeability of polyethylene bags containing the same thickness are somewhat greater than that of unmodified polyethylene bags of the same thickness. Samples A1 and A2 were enclosed in these bags with a modified atmosphere. In both cases, the oxygen concentration decreased to about 3% within two days, and the carbon dioxide concentration increased to over 5%. By day 9, oxygen levels were below 5% and carbon dioxide levels were approximately 20%. Thereafter, the oxygen concentration slowly increased in each case to about 5% and 8%, respectively, and the carbon dioxide concentration stabilized within the range of 15% to 20%. In the case of sample bags B1 and B2, the atmosphere after sealing was approximately 29% oxygen and approximately 3% oxygen, respectively.
% and about 5% carbon monoxide, with the remainder being substantially all nitrogen.
In each case, the oxygen concentration decreased to about 15% in 2 days, to less than 5% in the case of B1, and to about 6% in the case of B2 in 3 days. The concentration of carbon dioxide rose to about 15% in the case of B1 and about 10% in the case of B2 in three days. Carbon monoxide levels dropped to nearly zero within three days. After the third day,
In the case of B2, the concentration of oxygen was between about 2% and 4%, and the concentration of carbon dioxide was between about 15% and 18%. In the case of B1, due to an apparent leak, the oxygen concentration increased to a range of about 10% to about 12%, and the carbon dioxide concentration increased to about 17% to 19%.
rose to a range of Samples C1, C2, D1 and D2 were each placed in a package made of the same 8% ethylene vinyl acetate modified low density polyethylene as samples A1 and A2. However, these packages have a wall thickness of about 2.5 mils and a permeability of 1350 c.c. per 100 square inches, 1 mil and 24 hours of carbon dioxide, and 100
Permeability to oxygen per square inch, mil and 24 hours is 500 c.c. The atmosphere within sample packages C1 and C2 was not denatured. The atmosphere within both packages C1 and C2 decreased to less than about 5% oxygen and more than about 5% carbon dioxide in two days. By the third day after sealing, the concentration of carbon dioxide had risen to about 13% in both cases, and the concentration of oxygen had stabilized at about 3%. By the 12th day, the concentration of carbon dioxide in each case begins to rise again, rising to about 20% or more by the 18th day of storage, and the concentration of oxygen in each case about 3% after the 15th day. It slowly rose to about 5% by the 21st day. The atmosphere in packages D1 and D2 was modified to initially consist of approximately 35% oxygen in both cases, approximately 8% and 6% carbon monoxide, and the balance being essentially all nitrogen. . pack cage
Within both D1 and D2, oxygen and carbon monoxide concentrations decreased to below approximately 5% within 3 days. The oxygen concentration is about 4% on the 6th day in the case of D1.
However, in the case of D2, it did not rise above 5% at any point during the test period. The concentration of carbon dioxide increased to over 10% in two days.
It rose to about 15% or more in 3 days and about 20% in 6 days,
then approximately 20% during the remainder of the storage period.
It remained near the. The concentration of carbon monoxide is
In the case of D2, it will reach zero in 6 days, and in the case of D1, it will reach zero in 6 days.
It dropped to zero in a day. Samples E1, E2, F1 and F2 are each A1
and placed in a sealable package or bag made of low density polyethylene modified with about 8% ethylene vinyl acetate, the same as A2. Each bag measures 12 x 24 inches and has a wall thickness of 3.0
It was hot at the mill. These bags are 100 square inches, 1
The permeability to carbon dioxide per mil and 24 hours is 1350 c.c. and the permeability to oxygen per 100 square inches, mil and 24 hours is 500 c.c. The atmosphere within packages E1 and E2 was not modified. Within two days after sealing, the concentration of oxygen in each case decreased to about 3%, and thereafter did not rise above 5% in any case during the remainder of the storage period. The concentration of carbon dioxide rose in each case to about 15% or more in 3 days, to about 20% or more in 7 days, and to about 30% in 13 days. In the case of sample bags F1 and F2, the oxygen concentration was initially increased to approximately 34% in both cases, and the carbon monoxide concentration was increased to approximately 8% and 3%, respectively. The balance of each atmosphere was essentially all nitrogen. In each case, in 3 days the concentration of carbon monoxide decreased to zero and the concentration of oxygen was approximately 4
%. In both cases, the concentration of carbon dioxide rose to more than 15% in 3 days and about 25% in 12 days.
% or more. In each case the concentration of oxygen equilibrated around about 3% for the remainder of the storage period. Samples G1, G2, H1 and H2 are each approximately
It was enclosed in a package made of low density polyethylene modified with 3.5% ethylene vinyl acetate. Each package had dimensions of 12 x 24 inches and had a wall thickness of approximately 3 mils. These cages or bags have a permeability of 1350 c.c. to carbon dioxide per 100 square inches, 1 mil and 24 hours, and a permeability of 500 c.c. to oxygen per 100 square inches, 1 mil and 24 hours. It is. The atmosphere within packages G1 and G2 remained unchanged throughout the test. Within two days, the oxygen concentration in cases G1 and G2 had fallen to about 3% (and remained at 3% thereafter), and the carbon dioxide concentration had risen to more than 7% in each case. The concentration of carbon dioxide rose to about 15% or more in 3 days, and about 30% in 6 days.
It rose to above. The atmosphere in packages H1 and H2 initially consisted of about 35% and 28% oxygen, respectively, and in each case about 8% carbon monoxide, with the balance being essentially all nitrogen. All these were stored at 38〓. In both cases H1 and H2, the concentration of oxygen decreased to about 2% in 3 days,
Carbon monoxide levels dropped to near zero. On the other hand, the concentration of carbon dioxide rose to about 20% in 3 days, to about 30% in 9 days, and to about 35% in 13 days. Samples I1, I2, J1 and J2 are G1, G2, H1
and was placed in the same type of package cage as H2. After sealing, the atmosphere in sample packages I1 and I2 is approximately 12% oxygen in both cases;
They were modified to consist of about 9% and about 11% carbon monoxide, respectively, with the remainder being substantially all nitrogen. By the end of the third day of storage, the oxygen concentration in each package I1 and I2 had fallen to about 2%, and the carbon monoxide concentration had fallen to about 7% and 5%, respectively. Carbon monoxide concentrations decreased to zero in 9 days in each case. Oxygen concentrations were approximately 2% and 4% during the remainder of the test period.
It remained between. The carbon dioxide concentration in packages I1 and I2 will reach approximately 10% in 3 days and 15% in 7 days.
Moreover, it rose to more than 20% in nine days and more than 25% in 12 days. After sealing the sample packages J1 and J2, the atmosphere inside each package is approximately 30%.
and 25% oxygen, about 8% and about 3% carbon monoxide, with the balance being substantially all nitrogen. In three days, the oxygen concentration decreased to about 3% and about 5%, respectively, and the carbon monoxide concentration decreased to near zero percent. In each case, the concentration of carbon dioxide increased to about 10% or more in 3 days, and
It rose to more than 15% in one day, and more than 20% in seven days. In the case of J1, the carbon dioxide concentration rose to about 25% or more in nine days. Package I1, I2, J1
and J2 each contained one ounce of lime, which absorbed some of the carbon dioxide formed in the package. Samples K1, K2, L1, and L2 were all 1/2-inch lettuce pieces with shredded purple cabbage and ginseng, each with low density modified with 12% ethylene vinyl acetate. It was placed in a package or bag made of polyethylene. Each bag had dimensions of 12 x 24 inches and had a wall thickness of approximately 2.5 mils. These polyethylene bags are 100 square inches, 1 mil and 24
Permeability to carbon dioxide per hour is 1350c.c.
and has an oxygen permeability of 500 c.c. per 100 square inches, 1 mil and 24 hours. The atmosphere for samples K1 and K2 is approximately 35%
of oxygen, about 10% carbon monoxide, and the balance essentially all nitrogen. After 3 days of storage at 38°C, the oxygen concentration decreased to about 15% and the carbon monoxide concentration decreased to about 5% in both cases. The concentration of carbon dioxide increased to about 10% in both cases. After 6 days, the concentration of carbon monoxide in both K1 and K2 has decreased to near zero, and the concentration of oxygen has decreased to 5%.
It dropped to near. The concentration of carbon dioxide rose to about 15%. After that, in both cases, the oxygen concentration equilibrated at about 3%, and the carbon dioxide concentration equilibrated at about 16%. The atmosphere inside package L1 and L2 is initially approximately
It consisted of 33% to 35% oxygen, about 10% carbon monoxide, and the balance essentially all nitrogen.
In addition, sample packages L1 and L2 each contained one ounce of lime to absorb carbon dioxide emitted by the respiring lettuce. 38
After 3 days at 〓, the oxygen concentration decreased to about 10% in both L1 and L2.
On the other hand, the concentration of carbon dioxide increased to about 3%.
In both cases, after 6 days, the concentration of carbon monoxide was zero, the concentration of oxygen was less than 5%, and the concentration of carbon dioxide was less than 5%. After 16 days, the carbon dioxide concentration rose to about 13% for L1 and about 8% for L2. The increase rate and maximum value of carbon dioxide concentration obtained in the lettuce pieces package K1, K2, L1 and L2 are all in the lettuce shredded package cages A1, A2, B1,
B2, C1, C2, D1, D2, E1, E2, F1, F2, G1,
This was smaller than the values obtained for G2, H1, H2, I1, I2, J1 and J2, indicating that lettuce shreds breathe faster than lettuce pieces. A shredded lettuce cage must have a higher permeability to oxygen and carbon dioxide than a shredded lettuce cage, even if the lettuce is of the same type and weight. The following table details the number of days a lettuce sample can be stored at 38〓 before it begins to deteriorate.

[Table] Packages A1, A2, B1 and B2 are C1,
C2, D1 and D2 preserved lettuce shreds better, and C1, C2, D1 and D2 preserved lettuce shreds better than E1, E2, F1 and F2, but
This indicates that increasing sidewall thickness reduces oxygen and carbon dioxide permeability and shortens shelf life. Furthermore, in these tests, better results were always obtained if the concentrations of oxygen and carbon monoxide in the atmosphere within the package were initially increased to above 21% and 5%, respectively. The best results for shredded lettuce were obtained for samples B1 and B2, for which the initial carbon monoxide and oxygen concentrations in the sample bag and the permeability of the package were within the scope of the present invention. It was hot. The lettuce pieces (samples K1, K2, L1 and L2) breathe more slowly than the other sample shreds, in which case the lime keeps the concentration of carbon dioxide low and thereby in the case of these samples. Good results were obtained. EXAMPLE A piece of lettuce of the variety Montemar was cut into 1/2 inch pieces and each
They were divided into five groups, designated A1, A2-E1, and E2. Lettuce samples A1, B1, C1, D1
and E1 were each packaged in low density polyethylene bags measuring 12 x 24 inches and having a wall thickness of 1.5 mils. These polyethylene bags have a permeability of 1350 c.c. to carbon dioxide per 100 square inches, 1 mil and 24 hours, and a permeability of 500 c.c. to oxygen per 100 square inches, 1 mil and 24 hours.
It is. Samples A2, B2, C2, D2 and E2 are
Each was individually packaged in a high density polyethylene plus suurin bag measuring 12 x 24 inches and having a wall thickness of 1.5 mils. These polyethylene bags have a permeability of 1350 c.c. to carbon dioxide per 100 square inches, 1 mil and 24 hours, and a permeability of 500 c.c. to oxygen per 100 square inches, 1 mil and 24 hours. . The atmosphere within sample packages A1 and A2 was not denatured. Seal these packages
After 4 days of storage at 38〓, the oxygen concentration is about 7%.
The carbon dioxide concentration rose to about 8%. After 6 days, the oxygen concentration decreased to about 2% and the carbon dioxide concentration increased to about 10% in both cases. Thereafter, the carbon dioxide concentration decreased to about 7% or 8% and equilibrated. By the 12th day, the oxygen concentration rose to about 6% and remained at that value.
In the case of A2, it subsequently decreased to about 5% or less. The atmosphere in sample packages B1 and B2 was modified to consist of about 15% oxygen, about 7% carbon monoxide, and the balance essentially all nitrogen. After three days at 38〓, in each case the oxygen concentration had fallen to about 8% and the carbon monoxide concentration had fallen to about 1% and 3%, respectively.
After 6 days of storage, in the case of B1, the concentration of oxygen has decreased to about 4% and the concentration of carbon monoxide has decreased to about 3%.
%. In the case of B2, the oxygen concentration decreased to about 7% and the carbon monoxide concentration decreased to zero. The concentration of carbon dioxide increased to about 8% in the case of B1 and to about 10% in the case of B2. After 12 days, the atmosphere for B1 and B2 is 8% oxygen and about 9% carbon dioxide;
The remainder consisted of nitrogen. The atmosphere in sample packages C1 and C2 was initially modified to consist of approximately 33% oxygen and the balance essentially all nitrogen. 38
After 3 days at 〓, the oxygen concentration in C1 and C2 decreased to about 13% and about 15%, respectively, and the carbon dioxide concentration increased to about 7% and 5%, respectively. After that, the oxygen concentration in C1 was equilibrated, and the oxygen concentration in C2 decreased to less than 5% by the 8th day. In both packages, the carbon dioxide concentration remained around 10% and 4%, respectively, until the 5th day.
% and remained close to these values throughout the test period. The atmosphere in packages D1 and D2 was initially modified to consist of 28% by volume oxygen, approximately 9% and 7% carbon monoxide, and the remainder substantially all nitrogen. After 3 days at 38〓,
Oxygen concentration decreased to approximately 13% and 12%, respectively, and carbon monoxide concentration decreased to approximately 2% and 3%, respectively.
The carbon dioxide concentration rose to about 8% in both cases. After 7 days, carbon monoxide concentrations had fallen to near zero in both cases;
Carbon dioxide concentration rose to more than 10%, and oxygen concentration fell to about 10%. After that, the oxygen concentration decreased steadily and in each case reached a low value of about 3% after 11 days of storage. In both cases, the carbon dioxide concentration equilibrated at approximately 14% by day 8. The atmosphere within packages E1 and E2 was initially modified to consist of about 27% and 28% oxygen, respectively, and about 8% carbon monoxide, with the balance being substantially all nitrogen. Each package also contained one ounce of lime pieces to absorb carbon dioxide. After 3 days at 38〓, the concentration of carbon monoxide in each case decreased to about 17% and the concentration of carbon dioxide to about 3%. After 6 days, the oxygen concentration had decreased to about 8%, the carbon dioxide concentration had increased to about 7% and 5%, respectively, and the carbon monoxide concentration had decreased to about 1%. After 8 days of storage, the oxygen concentration in both packages was approximately 5
% and 4%, the carbon dioxide concentration was in equilibrium at about 8%, and the carbon monoxide concentration was close to zero. After 2 weeks at 38〓, samples A2, B2, C2,
D2 and E2 were opened and exposed to an atmosphere of 55〓. All of these samples exhibited good taste and aroma upon opening, and were not attenuated. However, sample C2 exhibited some discoloration. 55
After one day at 〓, all samples except B2 exhibited some degree of discoloration. After 4 days at 55〓, all samples exhibited weakness. B2 and D2 were in the best condition. Samples A1, B1, C1, D1 and E1 were kept sealed at 38°C for 3 weeks. Upon opening, samples C1, D1 and E1 exhibited good taste and aroma. C1 has significant discoloration and the sample
D1 and E1 exhibited the best color. After two days in an atmosphere of 55%, all samples were in a degraded state. Of these, sample D1 was the best. Taken as a whole, the samples initially packaged with increased oxygen and carbon monoxide concentrations, namely D1, D2, E1 and
E2 exhibited the best storage and longevity quality. EXAMPLE Salinas variety lettuce bulbs were cut into 1/2 inch pieces, A1, A2, B1, B2, C1, C2, D1, D2,
They were divided into 10 groups designated E1 and E2. Samples A1, B1, C1, D1 and E1 are 12×
It was packed in low density polyethylene measuring 24 inches and having a wall thickness of 1.5 mils. Sample A2, B2,
C2, D2, and E2 were packaged in high density polyethylene plus suurine bags measuring 12 x 24 inches and having a wall thickness of 1.5 mil. These polyethylene bags are
The permeability to carbon dioxide per 100 square inches, 1 mil and 24 hours is 1350 c.c., and the permeability to oxygen per 100 square inches, 1 mil and 24 hours is 500 c.c. The atmosphere for samples A1 and A2 was not modified. After these sample packages were sealed and stored at 38°C for 3 days, A1 and
The oxygen concentration in A2 decreased to about 8% and the carbon dioxide concentration increased to about 8%. After 6 days of storage at 38°C, the oxygen concentration decreased to about 5% and the carbon dioxide concentration increased to about 10% for both samples. After sealing samples B1 and B2, the atmosphere of each sample was modified to consist of approximately 34% and 32% oxygen, respectively, and the balance being substantially all nitrogen. After 3 days at 38〓,
The oxygen concentration in both samples decreased to about 15% and the carbon dioxide concentration increased to about 8%. After 6 days, the carbon dioxide concentration rose to about 12% in both cases, and the oxygen concentration fell to about 6%.
After 9 days, both had an oxygen concentration of about 3% and about 15
% carbon dioxide concentration. After that,
The concentrations of oxygen and carbon dioxide were in equilibrium. After sealing the sample packages C1 and C2, the oxygen concentration in each package was reduced to about 17%, carbon monoxide was introduced at a concentration of about 8%, and the balance was all nitrogen. After 3 days at 38〓, the carbon monoxide concentration is about 5% and about 4%, respectively.
%, the oxygen concentration decreased to about 8% in both cases, and the carbon dioxide concentration decreased to about 8% in both cases. After 6 days, the oxygen concentrations had decreased to approximately 6% and 5%, respectively, the carbon monoxide had both decreased to approximately 3%, and the carbon dioxide had both increased to approximately 11%. After 9 days, the oxygen concentration has decreased to about 3% and 5%, respectively, and the carbon monoxide concentration has both decreased to about 2%.
%, and the carbon dioxide concentration is about 3% in both cases.
and equilibrated at that value of 3% for the remainder of the test period. After sealing packages D1 and D2, the oxygen concentration was increased to about 32%, carbon monoxide was introduced at a concentration of about 9%, and the remainder of the atmosphere in each was essentially all nitrogen. 38〓
After 3 days, the concentration of carbon monoxide has decreased to about 4% in both cases, and the concentration of oxygen has decreased to about 16% in each case.
and about 17%, and the concentration of carbon dioxide rose to about 8% in both cases. After 6 days,
The oxygen concentration in both packages decreased to about 10%, the carbon dioxide concentration increased to about 10%, and the carbon monoxide concentration decreased to about 2%. After 9 days, the carbon dioxide concentration had risen to about 14% in each case, the oxygen concentration had fallen to about 4%, and the carbon monoxide concentration had reached zero. Thereafter, the oxygen and carbon dioxide concentrations equilibrated at approximately 4% and 13%, respectively. After sealing sample packages E1 and E2, the oxygen concentration was increased to about 33% in both cases, carbon monoxide was introduced at a concentration of about 6%, and the remainder of each atmosphere was essentially all nitrogen. .
After 3 days at 38〓, the oxygen concentration in each package will be approximately
The carbon monoxide concentration has decreased to approximately 3%, and the carbon dioxide concentration has decreased to approximately 2% in package E1.
However, it did not increase at all in E2. 6
After days, the oxygen concentration is about 7% and about 9%, respectively.
%, and the carbon monoxide concentration was about 3% in both cases.
The carbon dioxide concentration did not rise above 2%. After 9 days, the oxygen concentration in each case decreased to about 4% and reached equilibrium at that value, and the carbon monoxide concentration decreased to almost zero. Carbon dioxide levels remained at or near zero throughout the test, primarily because packages E1 and E2 each contained 2 ounces of lime to absorb carbon dioxide. Sample packages A1, B1, C1, D1 and
E1 was stored for two weeks at 38〓 and later opened. The appearance of the lettuce from all these packages was good, but sample packages A1 and C
The lettuce from the plant was noticeably deodorized and deflavored. Samples A1, B1, C1, D1 and E1 were then stored at 50°C in air. After two days in the air, the lettuce from sample E1 became wilted and turned pink. Lettuce from samples A1 and B1 turned pink. After 4 days in the air, the lettuce from sample E1 was in the worst condition. Lettuce from samples A1 and B1 had the poorest color. The lettuce from samples D1 and E1 was the best in terms of taste, and the lettuce from sample D1 was the best in terms of appearance. Lettuce samples A2, B2, C2, D2 and E2 are
It was stored for 3 weeks at 38〓 and later released. Lettuce from sample C2 was the worst in terms of taste and aroma. Lettuce from samples A2 and E2 tasted the best. Lettuce from B2 and D2 passed in terms of taste. All samples A2-E2 were then exposed to air at 50°C for 5 days. 2
After a few days, samples A2 and E2 showed a moderate pink discoloration, but the deterioration was more pronounced in samples A2 and C2. After 5 days, all lettuce samples were unacceptable in color, but samples
B2 and D2 did not exhibit any weakness. Overall, the shelf life was best for samples D1 and D2, which were initially exposed to oxygen concentrations no higher than about 30% and about 5%.
The lettuce was packaged with a modified atmosphere having a carbon monoxide concentration not higher than %. EXAMPLE Lettuce bulbs of the Montemar variety were cut into pieces of 1/2 inch size, A1, A2, B1, B2, C1, C2,
Divided into 10 groups designated D1, D2, E1 and E2. Samples A1, B1, C1, D1 and E1 were packaged in low density polyethylene bags having dimensions of 12 x 24 inches and a wall thickness of 1.5 mil. These bags have a permeability of 1350 c.c. for carbon dioxide per 100 square inches, 1 mil and 24 hours, and a permeability of 500 c.c. for oxygen per 100 square inches, 1 mil and 24 hours. Samples A2, B2, C2,
D2 and E2 were packaged in high density polyethylene plus suurine bags measuring 12 x 24 inches and having a wall thickness of approximately 1.5 mils. These bags are 100 square inches,
100 square inches, 1 mil and 24 hour carbon dioxide permeability of 1350 c.c.
The permeability to oxygen per 24 hours is 500c.c. Sample packages A1 and A2 were sealed without denaturing the atmosphere within them. 38
〓 After 3 days, the oxygen concentration is about 8% in both cases.
and the carbon dioxide concentration rose to about 6% and 9%, respectively. After 6 days at 38〓, the carbon dioxide concentration increased to 10% and 13%, respectively, and the oxygen concentration decreased to about 4%. 9
After a day, the oxygen concentration decreased to about 2% and the carbon dioxide concentration increased to about 13% and 15%, respectively. After 12 days, the oxygen concentration equilibrated at about 1% and the carbon dioxide concentration at about 13% and 18%, respectively. After sealing samples B1 and B2, the atmosphere inside each package was approximately 35% and 33% oxygen;
It was modified to consist of substantially all nitrogen with the remainder being nitrogen. After 3 days at 38〓, B1 and B2
The oxygen concentration at the site decreased to approximately 15%, and the carbon dioxide concentration increased to approximately 10%. After 6 days at 38〓, the oxygen concentration decreased to about 3%, and the carbon dioxide concentration increased to about 12% and 15%, respectively. After 9 days at 38〓, samples B1 and B2
The oxygen concentration at 200 nm decreased to approximately 2%, and the carbon dioxide concentration increased to approximately 13% and 17%, respectively, and equilibrated at these values. After the packages containing lettuce samples C1 and C2 are sealed, the atmosphere within each of the packages consists of approximately 16% oxygen, approximately 7% carbon monoxide, and the balance being substantially all nitrogen. denatured as such. After three days at 38〓, the atmosphere at C1 and C2 consisted of about 5% oxygen, 5% carbon monoxide, and about 8% carbon dioxide. After 6 days at 38〓, the concentration of oxygen and carbon monoxide both decreased to about 4%, and the concentration of carbon dioxide increased to about 13%. After 9 days at 38〓, the oxygen and carbon monoxide concentrations equilibrated at about 3%, and the carbon dioxide concentration equilibrated at about 18%. Thereafter, the carbon monoxide concentration in sample package C2 decreased to near zero by day 15, as did the oxygen concentration in both sample packages. The carbon monoxide concentration in sample package C1 equilibrated at approximately 3% by the 15th day of storage. After sealing the packages containing lettuce samples D1 and D2, the atmosphere in each sample was approximately 27% and 36% oxygen and 3% and 5% oxygen, respectively.
% carbon monoxide and the remainder substantially all nitrogen. After 3 days at 38〓, the atmosphere at D1 and D2 is about 3% carbon monoxide and about 10% carbon dioxide, respectively.
10% and 23% oxygen. 6
After a day, the carbon dioxide concentration rose to about 13% in both cases, the oxygen concentration fell to about 5% and 14%, respectively, and the carbon monoxide concentration fell to about 2% in both cases. After 9 days, the carbon monoxide concentration was almost zero, the oxygen concentration was about 2%, and the carbon dioxide concentration was about 15%. From day 9 to day 21, the oxygen and carbon monoxide concentrations gradually decreased toward zero, and the carbon dioxide concentration continued to rise until it was above 15%. After the packages containing samples B1 and B2 are sealed, the atmosphere within each of them is about 32% and 34% oxygen, respectively, and about 5% carbon monoxide, with the balance being substantially all nitrogen. It has been modified to become more. After three days at 38〓, the oxygen concentration in each package decreased to approximately 15%, and the carbon monoxide concentration decreased to approximately 28%. After 6 days, the oxygen concentrations had decreased to about 7%, the carbon monoxide concentrations had decreased to about 1%, and the carbon dioxide concentrations had decreased to about 3% and 4%, respectively. After 9 days of storage at 38〓, the carbon monoxide concentration decreased to almost zero, the oxygen concentration decreased to about 2%, but the carbon dioxide concentration increased only to about 3% in the case of E1, In the case of E2, it rose only to about 6%. After that, the concentration of oxygen and carbon monoxide decreased to near zero, and the concentration of carbon dioxide continued to rise, but did not exceed 7% in the case of E1.
In the case of E2, it did not exceed 10%. The two ounces of lime in each bag absorbed much of the carbon dioxide produced by absorption. After being stored for 2 weeks at 38°, sample packages A1, B1, C1, D1 and E1 were opened and stored in an atmosphere of 50° for 5 days. When you first open these packages, sample A1,
Lettuce from B1 and D1 exhibited good appearance and flavor. The lettuces from samples C1 and E1 were noticeably de-aromatized and de-flavored. No weakening or discoloration was observed in any of the samples. After being stored for 3 days at 50°C, all lettuces showed slight discoloration but no deterioration. After 5 days at 50 ml, only the lettuce from sample E1 was weakened and exhibited a moderate pink discoloration. Lettuce sample B1
and D1 were the best in terms of flavor and appearance. Lettuce samples A2, B2, C2, D2 and E2 are
Opened after 3 weeks of storage at 38°C, all lettuces had a good appearance. sample
Lettuces from E2 and B2 are the best in terms of taste,
The lettuce from sample D2 was a little bland;
The lettuce from sample C2 had a noticeable lack of flavor. All lettuce samples A2-E2 were stored in air at 50ⓓ for 6 days. After 3 days at 50%, only sample E2 changed color. After 4 days, sample B2
The lettuce from
Lettuce from A2 exhibited some degree of weakness. 6
Even after several days, the lettuce from samples D2 and C2 did not exhibit any weakening or discoloration. Lettuces from all other samples, A2, B2 and E2, were noticeably weakened and discolored. Overall, it has a modified atmosphere consisting initially of an oxygen concentration of no more than about 25%, a carbon monoxide concentration of no more than about 5%, and the balance being substantially all nitrogen. The cut lettuce, namely samples D1 and D2, packed with
It was the best in all respects of shelf life. EXAMPLE Four bundles of cut broccoli were placed in a sealable bag made of low density polyethylene modified with 4.5% ethylene vinyl acetate. The walls of these bags had a thickness of approximately 1.5 mils. These 4 are made of cut broccoli
The three samples were labeled A, B, C, and D, respectively. The atmosphere within the bag containing Sample A was initially modified to contain approximately 29 percent oxygen, approximately 5 percent carbon monoxide, and the remainder substantially all molecular nitrogen. The atmosphere inside the bag containing Sample B was not denatured. The atmosphere within the bag containing Sample C was initially modified to contain approximately 14 percent oxygen, approximately 19 percent carbon monoxide, with the balance being substantially all molecular nitrogen. In addition, 2 ounces of lime was also placed in the bag containing Sample C.
The atmosphere within the bag containing Sample D was unaltered, but 2 ounces of lime was added before sealing. The bags containing samples A, B, C and D were each sealed and then maintained at a temperature of 38° for 3 weeks. During that period, the oxygen concentration surrounding Sample A decreased from 29% to 15% by day 3 and remained at that level for the remainder of the test period. On the other hand, the carbon dioxide concentration was initially zero, rose to about 13% by day 6, and then began to decline, reaching 8% by the end of the three week period. The carbon monoxide concentration in the bag containing Sample A was initially 12% by volume, decreased to approximately 2% within two days, and remained at approximately 2% for the remainder of the test period. The atmosphere inside the package containing sample B is
The oxygen concentration, which was initially 12%, decreased to about 2% by the second day.
% and remained at that level for the remainder of the study period. The carbon dioxide concentration around Sample B rose to 8% by the second day and remained at or near 8% for the remainder of the test period. In sample bag C, the carbon monoxide concentration decreased to 10% by day 3, to approximately 3% by day 6, and remained near 3% for the remainder of the test period. The oxygen concentration dropped to about 1% within two days and remained near 1% for the remainder of the test period. In sample bag D, the oxygen concentration dropped to about 2% within two days and remained near 2% for the remainder of the test period. After being stored for 3 weeks at 38〓, the bag was opened and
The appearance of the broccoli within the bags was visually inspected. The results are shown in the following table.

[Table] As is clear, the best results were obtained with sample A, in which there was almost no discoloration and the overall appearance was very good. EXAMPLE Ten pounds of shredded cabbage was placed into a low density polyethylene bag formed from sheet material approximately 1.5 mils thick. The bag is sealed,
The atmosphere therein was modified to contain about 23% oxygen, about 3% carbon monoxide, and about 74% nitrogen. The bag was stored for 19 days at 38〓. During a period of 19 days, the gaseous atmosphere inside the bag was analyzed several times. After being stored for 2 days, the oxygen concentration is about 5
% and gradually increased to about 15% by the end of the study period. The concentration of carbon monoxide is approximately 2 in 2 days.
%, dropped to zero in four days, and remained at that zero level for the remainder of the study period. The carbon dioxide concentration decreased from near zero initially to about 10% in 6 days and equilibrated at about 5% for the remainder of the test period. The cabbage in this bag had a very good appearance even after being stored for 14 days. At the end of the test period, the cabbage had a good aroma and taste, but there was some discoloration on the cut surfaces. A sufficiently high initial carbon monoxide concentration could prevent such discoloration. Example Made of cut cauliflower, each made of approx.
Four samples (A, B, C) weighing 2.5 lbs.
and D) were placed on a foamed plastic array having dimensions of 9 x 10 x 0.625 inches and each was enclosed in a low density polyethylene bag formed of 1.5 mil thick sheet material. Four more samples of the above cauliflower (designated E, F, G and H) each weighing about 2.5 pounds were placed in a tray having the same type and dimensions, and a sheet material having a thickness of about 2.0 mils. encapsulated in a low-density polyethylene bag. Four other samples (designated I, J, K, and L) consisting of cut cauliflowers weighing approximately 0.75 pounds each weighed 4.5 x 8.5 x
It was placed on a foam plastic tray having dimensions of 0.625 inches and enclosed within a polyvinyl chloride bag made of sheet material having a thickness of approximately 0.5 mil. After sample bags I and J are sealed, the atmosphere within them is approximately 50% and 45% oxygen, approximately 5% and 4% carbon monoxide, and substantially all nitrogen. modified to include the remainder. Samples K and L were also sealed, but the atmosphere within these bags was undenatured air. All four sample bags were stored at 38㎜.
Samples I and K were stored for 14 days and then opened, and samples J and L were stored for 21 days and then opened. Throughout these storage periods, the gaseous atmosphere within each bag was analyzed several times. In Sample I, the oxygen concentration decreased to about 15% in 2 days, to about 3% in 6 days, and remained at that level for the remainder of the test period. Carbon monoxide concentration gradually decreased to about 1% over the storage period. The carbon dioxide concentration increased from an initial near zero value to about 2% within two days and remained at or near that level for the remainder of the test period. In Sample K, the oxygen concentration decreased to approximately 10% in 3 days and equilibrated at that level for the remainder of the test period. The carbon dioxide concentration rose from an initial near zero level to about 1 percent and remained at approximately that level for the remainder of the test period. In Sample J, the oxygen concentration decreased to about 20% in 2 days, to about 10% in 6 days, and remained at or near that level for the remainder of the test period. The carbon monoxide concentration decreased to about 1% in about 3 days, to near zero in 6 days, and remained at that near zero level for the remainder of the test period. The concentration of carbon dioxide increased from nearly zero at the beginning to about 1% and remained at that level throughout the test period. For Sample L, the oxygen concentration dropped to about 10% in 2 days, to about 5% in 3 days, and remained at or near about 3% for the remainder of the test period. The carbon dioxide concentration in this sample rose from an initial near zero to about 2% and remained at or near that level for the remainder of the test period. In the case of samples I and K, after 14 days of storage, the packages containing these samples were opened and the samples inside were observed. The cauliflower from the unmodified atmosphere had a slight discoloration, and the cauliflower treated with carbon monoxide () had a fresh appearance. All samples showed no floret mold or weakness, and the taste and aroma of cauliflower was good in all treatments. After storing the cauliflower at 45°C for 3 days, the untreated cauliflower changed color significantly, while the carbon monoxide treated cauliflower only slightly changed color. In this case, neither floret pattern nor weakness was observed in any of the cauliflowers. After sealing samples A and C, the atmosphere inside these bags is about 48% and about 43%, respectively.
% oxygen, about 5% carbon monoxide, with the remainder being substantially all nitrogen. Samples B and D were also sealed, but the atmosphere within these bags was not modified. In addition to the modified atmosphere, samples A and B also contained lime, which absorbed carbon dioxide. All four samples were stored for 21 days at 38㎓. Throughout these periods, the gaseous atmosphere within each bag was analyzed several times. In Sample A, the oxygen concentration decreased to about 30% in 3 days, to about 3% in 6 days, and remained at that level for the remainder of the test period. In sample B, the oxygen concentration was approximately 3% in 3 days.
It decreased to about 1% by day 6 and remained at or near that 1% level for the remainder of the study period. In the case of sample C, the oxygen concentration decreased to about 20 in 3 days.
%, decreased to about 10% by day 6, to about 3% by day 9, and remained at or near that 3% level for the remainder of the study period. The concentration of carbon monoxide gradually decreased from about 5% to about 2% by the end of the test period. The carbon dioxide concentration was initially near zero, rose to a high value of about 10% within 7 days, and then gradually decreased to a level of about 7% or 8% over the remainder of the test period. In sample D, the oxygen concentration decreased to approximately 10% in 3 days and remained at that 10% for the remainder of the test period.
remained at or near that level. The carbon dioxide concentration increased to about 5% in 6 days and then decreased to about 2% by the end of the test period. At the end of the three week storage period, sample A
The cauliflower from the plant gave the best appearance. There was no discoloration on the surface of the cauliflower, floret pattern and weakening were prevented, and no aroma was detected.
The cauliflower from Sample B was noticeably weaker and discolored. The cauliflower from Sample C had a good appearance, but the aroma was noticeably lost.
The cauliflower from Sample D was noticeably discolored and exhibited floret pattern and weakness. The cauliflower from Sample A exhibited good appearance after storage for 3 weeks at 38° followed by 5 days at 45°. After samples E and G were sealed, the atmosphere inside these bags was approximately 51% oxygen and approximately 5% oxygen.
% carbon monoxide with the remainder being substantially all nitrogen. Samples F and H
were also sealed, but the atmosphere inside these bags was not denatured. These four sample bags were all stored at 38㎓ for 14 days. Both gaseous atmospheres were analyzed several times throughout this period. In sample E, the oxygen concentration decreased to approximately 30% in one day.
It decreased to about 20% in 3 days, to about 10% in 5 days, and then gradually decreased to almost 3% by the end of the study period. Carbon monoxide concentration ranges from 5% to about 1% in 6 days
and remained at or near that 1% level for the remainder of the study period. For sample F, the oxygen concentration decreased to 5% within 2 days and then gradually decreased to about 2% by the end of the test period. In sample G, the oxygen concentration reached 40% in 3 days.
It decreased to about 20% in 5 days, to about 10% in 8 days, to about 5% in 9 days, and then to about 1% by the end of the test period. Carbon monoxide concentrations remained at or near 5% throughout the test period. The concentration of carbon dioxide increases from about zero in the first 7 days.
It increased to a maximum value of 10% and then decreased to about 5% by the end of the study period. In sample H, the oxygen concentration decreased to 10% in 1 day, to about 5% in 3 days, to about 2% in 6 days, and then increased to about 4% by the end of the test period. The carbon dioxide concentration for Sample H increased from an initial near zero to about 5% and remained at or near that 5% level for the remainder of the test period. Upon opening Samples E, F, G, and H, at the end of the test period, Sample E, which had lime in the package throughout the test period, had the best appearance. The taste and aroma of the cauliflower from Sample E was good, and no floret pattern or weakening was observed. Sample F also contained lime throughout the test period, but the cut surface showed some loss of aroma and some discoloration. Sample G was good in terms of appearance, but
There was a lack of aroma in this sample, due in part to the lack of lime. Sample H passed the test in terms of aroma, but some discoloration was observed on the cut surface. Sample E following the end of the two-week test period;
After holding F, G and H at 45〓 for 3 days,
Only sample F was in good condition. Examples It was placed in a bag made of polyethylene containing approximately 4.5% ethylene vinyl acetate. Two additional celery samples of approximately the same weight and composition were placed in bags made of polyethylene doped with 8% ethylene vinyl acetate. These bags were formed from sheet material having a thickness of approximately 2.0 mils. Celery samples (A, B, C, D, E, F, G
After sealing each of the bags containing (denoted as and H) sample packages A, B, C and D were stored at 38°C without denaturing the atmosphere inside these bags. Samples E and F contained an atmosphere within these bags of approximately 40% and 36% oxygen, and approximately 12% oxygen, respectively.
It was modified to have carbon monoxide and the balance being essentially all nitrogen and then stored at 38°C. After samples G and H are sealed, the atmosphere within these bags is such that the concentration of oxygen is approximately 15%, the concentration of carbon monoxide is approximately 16%, and the remainder is substantially all molecular nitrogen. denatured. These samples were also stored at 38㎓. Samples B and D were stored for 14 days at 38°C. Over the time interval, the oxygen concentration in Sample B decreased to about 10% in 3 days, to about 5% in 6 days, and remained at or near the 6% level by the end of the period. The carbon dioxide concentration in sample B increased from almost zero at the beginning to 6
5% by day and 6% by the end of the period.
remained at or near the level of The concentration of carbon dioxide in Sample B increased from initially near zero to about 5% in 6 days and remained at or near that 5% level for the remainder of the test period. In sample D, the oxygen concentration is approximately
It decreased to 15% and then remained at or near 15% for the remainder of the study period. The carbon dioxide concentration rose to about 2% and remained at about that value throughout the test period. Samples A and C were stored for 21 days at 38°C before being opened. In Sample A, the oxygen concentration decreased to about 10% in 3 days, to about 5% in 6 days, and remained at or near that 5% level for the remainder of the test period. The carbon dioxide concentration in sample A decreased from near zero to approximately 5 in 6 days.
% and remained at that 5% level for the remainder of the 21-day study period. In sample C, the oxygen concentration reached 10% in 3 days and 5% in 6 days.
% and then gradually decreased to about 4% over the remainder of the test period. The carbon dioxide concentration, which was initially near zero, increased to about 5% in 15 days and then remained near that 5% level for the remainder of the test period. Even after storage for 14 days at 38%, the celery from samples B and D remained good in terms of taste;
The cut end was slightly discolored. The celery from Samples A and C had a poor appearance due to discoloration at the cut ends, but had a good taste. After 3 days of storage at room temperature, Samples B and D exhibited a more pronounced discoloration, while Samples A and C exhibited discoloration at the end of the test period. In the case of sample package E, the oxygen concentration reached approximately 28% in 3 days, approximately 20% in 8 days, and approximately 20% in 15 days.
10% and about 15% by the end of the three week study period. The carbon monoxide concentration in sample E decreased from about 12% to about 5% in 14 days,
Approximately 5% to approximately 4% by the end of the 3-week test period
It dropped to . The carbon dioxide concentration was initially near zero, rose to about 5% within 6 days, and remained at or near that 5% level for the remainder of the test period. In the case of sample G, the oxygen concentration decreased to about 10 in 2 days.
% and approximately 5% in 5 days, then gradually decreased to approximately 3% and remained at that level for the remainder of the study period.
The concentration of carbon monoxide in sample G was approximately
It decreased from 12% to approximately 10% and then gradually decreased to approximately 6% by the end of the 3 week study period. The concentration of carbon dioxide in Sample G was initially near zero, rose to about 3%, and remained at that level for the entire three week period. At the end of three weeks, sample packages E and G were opened and their appearance observed. The celery from Sample E had a very good appearance and no flavor loss. The celery from Sample G had a very good appearance, but was somewhat lacking in flavor. After 2 days at room temperature, the celery from Sample E retained a good appearance, but exhibited some discoloration after 3 days. In the case of sample G, some flavor loss remained after 2 and 3 days. In the case of sample package F, the oxygen concentration was initially about 36%, but it decreased to about 20% in 5 days, to about 10% in 9 days, and then at the end of the 2-week test period. It gradually declined to about 3%. The carbon monoxide concentration was initially about 12%, but
It decreased to about 10% in 1 day and remained at or near that level until the end of the 2 week study period. In the case of sample package H, the oxygen concentration decreased to about 10% in 2 days, to about 5% in 4 days, and to about 2% in 8 days; It remained at a level of %. The concentration of carbon monoxide gradually decreased to about 12% by the end of the test period. The carbon dioxide concentration was initially near zero, rose to about 5%, and remained at or near 5% throughout the test period. When sample packages F and H were opened at the end of the two week storage period, the celery from sample package F was very good in appearance and showed no discoloration on the cut surfaces. The celery from Sample F had a good appearance, but some loss of flavor and aroma was observed. Celery from Sample F retained good appearance even after storage for 3 days at room temperature. The celery from Sample H retained some aroma, but had a good appearance.

Claims (1)

Claims: 1. A modified atmosphere comprising at least one vegetable and at least about 25% by volume oxygen, at least about 3% by volume carbon monoxide and the remainder substantially all molecular nitrogen, comprising: A sealed package having a permeability to carbon monoxide and carbon dioxide at least as high as that of low density polyethylene having a thickness not greater than about 2 mils. 2. The package according to claim 1, wherein the vegetables are cut vegetables. 3. The package of claim 1, wherein said atmosphere includes at least about 40% oxygen by volume. 4 Claim 3 in which the vegetable is lettuce
Package described in section. 5. The package of claim 4, wherein said package is formed from a flexible sheet material. 6 Claim 1 in which the vegetable is lettuce
Package described in section. 7. The package of claim 1, wherein the package and its contents are maintained at a temperature below 45°C and above the freezing temperature of moisture within the at least one vegetable. 8. The package of claim 1, wherein the at least one vegetable is selected from the group consisting of lettuce, celery, green onion, broccoli, cauliflower, parsley, and cabbage. 9 Oxygen permeability per 100 square inches of package surface, 1 mil of package thickness and per 24 hours is at least about 500 c.c. has a permeability to each of carbon monoxide and carbon dioxide of at least about 1350 c.c. A sealed package containing a modified atmosphere consisting of the remainder being molecular nitrogen. 10. The package according to claim 9, wherein the vegetables are cut vegetables.