Modified Gas Atmosphere Research Articles

Effect of modified gas atmosphere packaging after dip treatment on myoglobin and lipid oxidation of beef steaks

Fresh beef loin steaks were packaged in atmosphere of: (A) 20% CO 2 + 80% O 2 after dip treatment (dipped in 70% ethanol solution containing 3% l-ascorbic acid and 0·08% dl-α-tocopherol), (B) air after dip treatment, (C) 20% CO 2 + 80% O 2 without dip treatment and (D) air without dip treatment (control). After 3,6,9 and 13 days' storage at 4°C, the samples were evaluated for MetMb formation, TBA number and pH. The beef steaks stored in 20% CO 2 + 80% O 2 with or without dip treatment for 13 days maintained an acceptable meat colour. The TBA numbers of samples stored for 13 days in air and 20% CO 2 + 80% O 2 after dip treatment were significantly lower than those of samples without dip treatment. Beef steaks stored for 13 days in 20% CO 2 + 80% O 2 after dip treatment exhibited no change in pH. Data suggested that dip treatment with ascorbic acid and tocopherol solutions before modified gas atmosphere packaging was very suitable for the storage of retail cuts of beef loin steak.

Microbiology of spoilage of a perishable pomegranate product

Pomegranate kernels were stored in plastic pouches in a modified gas atmosphere under refrigeration. The storage life of this product (3–4 weeks at 1°C) was limited by off-flavours produced by microbial metabolism; yeasts and acetic acid bacteria were the predominant spoilage organisms.

THE UTILIZATION OF MODIFIED GAS ATMOSPHERE PACKAGING FOR FRESH MEAT: A REVIEW

ABSTRACT Distribution and packaging methods that are used for fresh meats have changed drastically over the past decade from primarily the shipment of carcasses to vacuum packaged primal cuts. Research efforts are now being directed at the replacement of vacuum packaging with modified gas atmospheres which may be more cost efficient and reduce trim losses. This paper reviews some of the more current research which has been conducted in modified gas atmosphere packaging.

Storage Characteristics of Finfish Fillets (Archosargus probatocephalus) Packaged in Modified Gas Atmospheres Containing Carbon Dioxide

Sheepshead (Archosargus probatocephalus) fillets were stored in air and in modified gas atmospheres consisting of: 100% CO2, 80% CO2:20% O2, 60% CO2:40% O2, 30% C02:60% O2, 20% CO2:80% O2, 40% CO2:60% N2 and 44% CO2:36% O2:20% N2 At regular intervals during refrigerated storage, numbers and types of microorganisms and total volatile nitrogen (TVN) were determined. Increases in aerobic plate counts of fish fillets held in air and in 20% C02:80% O2 were greater than those for fillets stored in the other gas atmospheres. The most effective combinations of gas for limiting bacterial growth were 100% CO2 and 40% CO2:60% N2. Total volatile nitrogen values of samples stored in air and in 20% CO2:80% O2 increased similarly to those of fish held on ice. At higher CO2 concentrations, however, increases in TVN were slow and the rate of TVN production appeared inversely proportional to CO2 tension.

Packaging of Beef Loin Steaks in 75% O2 plus 25% CO2. I. Physical and Sensory Properties

U.S. Choice boneless beef strip loins from four suppliers were used to determine the effect of using previously vacuum-packaged beef subprimals and the effect of using subprimals at different storage intervals--0, 14 or 28 days--after arrival at our laboratory on the retail appearance of steaks packaged in 75% O2 + 25% CO2. After packaging, steaks were stored for 9 days in the dark in a 1 ± 1-C refrigerated cooler and displayed under 1030 lux of incandescent light in a retail case for 4 days at 2 ± 2 C. Selected subprimals were repackaged and held at 1 ± 1 C for 9 days in the dark and steaks were removed and packaged in polyvinyl chloride (PVC) film and displayed for 4 days to serve as display controls. With regard to surface discoloration, overall appearance and off-odor scores, modified gas atmosphere (MGA)-packaged steaks from strip loins fabricated at Day 0 were not different (P>.05) from PVC-packaged steaks, however, MGA-packaged steaks from strip loins fabricated at Day 14 or Day 28 were less desirable (P<.05) than PVC-packaged steaks or steaks that were MGA-packaged on Day 0. When comparisons of retail appearance characteristics were made among loins from different suppliers, the results were mixed; data from steaks that were MGA-packaged at Day 14 revealed (P<.05) differences among loins from different suppliers in surface discoloration and off-odor while data from steaks that were MGA-packaged at Day 28 revealed no (P>.05) differences among loins from different suppliers in surface discoloration or overall appearance. Data indicate that modified gas atmosphere packaging of beef loin steaks can be successful if very fresh subprimals are used; however, extended vacuum-storage of beef subprimals (14 or 28 days) did not provide raw material that was amenable to subsequent storage-display in modified gas atmosphere packages.

Biochemical changes in tomatoes stored in modified gas atmospheres. I. Sugars and acids

SUMMARYDuring long‐term storage in modified gas atmospheres (MGA), some of the biochemical changes occurring in tomato fruit, cv. Sleaford Abundance, were compared with those in fruit of some Israeli cultivars which had been selected for firmness and slow ripening. The MGA used in the experiments did not succeed in completely restricting changes in sugars and acids during storage, although colour change was prevented. This separation of processes is discussed in relation to the practice of long‐term storage and its implications for fruit flavour.

Biochemical changes in tomatoes stored in modified gas atmospheres. II. Isoenzymes involved in glycolysis and the citric acid cycle

SUMMARYA comparative study of the isoenzymes involved in sugar and organic acid metabolism was made during long‐term storage of Sleaford Abundance, a poor storing tomato cultivar, and several breeding lines selected for fruit firmness or retarded ripening. Of the enzymes investigated, major changes occurred in hexokinase, enzymes of the hexose monophosphate shunt, NADH and NADPH dehydrogenase during storage but no major differences in the patterns of enzyme change were detected between cultivars.

Appearance of Beef, Pork and Lamb Stored in Vacuum or Modified Gas Atmospheres

Beef, pork and lamb loins were vacuum-packaged as subprimal cuts, vacuum-packaged as reformed subprimal cuts, vacuum-packaged as retail cuts or packaged in modified gas atmospheres as retail cuts. Cuts were stored and evaluated, after 0, 7, 14 or 21 days of storage, for surface discoloration and overall appearance. Gas analysis of the heads pace of packages was also obtained. In all vacuum packaging treatments, the percentage of CO2, increased and the percentage of O2, decreased with increased storage. The gas composition in modified gas atmosphere packages changed little during the 21-day study. Using systems and gas combinations involved in the present study, retail cuts of beef, pork and lamb could not be successfully precut, retail-packaged and stored for 7 to 21 days in vacuum or modified gas atmospheres. Vacuum-packaged retail cuts and retail cuts stored in modified gas atmospheres sustained extensive surface discoloration and were of unsatisfactory appearance, even after only 7 days of storage and 1 day of retail display. Conversely, storage of retail cuts as vacuum-packaged reformed subprimal cuts for 7 to 21 days decreased (P < .05) surface discoloration and improved (P < .05) overall appearance in comparison to retail cuts from loins stored as subprimals for comparable times in vacuum packages.

Microbiology of Beef, Pork and Lamb Stored in Vacuum or Modified Gas Atmospheres

Beef, pork and lamb loins were vacuum-packaged as subprimal cuts (controls), reformed subprimal cuts and as retail cuts (steaks or chops). Subprimal cuts, reformed subprimal cuts and one group of retail cuts remained vacuum-packaged. Other groups of retail cuts were injected with atmospheres of either 20% CO2 + 80% N2 or 40% CO2 + 60% N2. Cuts were randomly assigned to storage periods of 0–21 days at 2 ± 1 C. At weekly intervals, steaks or chops were removed from each treatment and examined after storage for 5 days under retail display conditions. Psychrotrophic bacterial counts and lactobacilli counts of steaks and chops stored in CO2-N2 atmospheres usually were lower, though not often statistically significant, than those of comparable vacuum-packaged steaks, chops or loins. Psychrotrophic counts of steaks and pork chops, initially held in CO2,-N2 atmospheres and then subjected to retail display, usually were lower than those of comparable steaks and chops that had been vacuum-packaged (without added CO2-N2) or prepared from vacuum-packaged loins.

Comparative physiology of field‐grown tomatoes during ripening on the plant or retarded ripening in controlled atmospheres

SUMMARYTomato fruits of six cultivars were harvested at three different stages of maturity or were harvested when mature‐green and then stored in a modified gas atmosphere (2·5‐4% O2; 4% CO2) for 2 months. The fresh and stored fruits were analysed for their contents of sugars, organic acids and free amino acids, while proteins were separated by discontinuous electrophoresis on polyacrylamide gels. In general, the low molecular weight components decreased during storage. A comparison of mature‐green fruits before and after storage showed that although total protein was not decreased, a different electrophoretic pattern was obtained following controlled atmosphere (CA) storage. Thus, although controlled atmosphere storage repressed the loss of chlorophyll and synthesis of lycopene, carotenoids and xanthophylls, the biochemical parameters measured showed a controlled change towards the conditions exemplified by ripe fruits. This was not so marked in some cultivars as it was in others.

Microbiology of Pork Packaged in Various Gas Atmospheres

Boneless pork roasts were vacuum-packaged; one group remained in vacuum-packages (controls), other vacuum-packages were injected with one of six gas mixtures: (a) 100% O2, (b) 20% CO2 + 80% N2, (c) 50% CO2 + 50% O2. (d) 20% CO2 + 80% O2, (e) 25% CO2 + 25% O2 + 50% N2, or (f) 51% CO2 + 30% O2 + 18% N2 + 1% CO. Roasts were stored from 0–35 days at 1–3 C and chops from each treatment were observed under retail conditions for 5 days. Differences, both in psychrotrophic and lactobacillus counts, between roasts stored in modified gas atmospheres and those stored in vacuum-packages were rarely statistically significant. Psychrotrophic counts of pork chops from roasts stored for 21–35 days in modified gas atmospheres were somewhat higher than those prepared from comparable vacuum-packaged roasts. However, few of these differences were statistically significant. The initial microbial flora of the roasts consisted of Pseudomonas and Lactobacillus spp. Pseudomonas spp. remained a significant part of the microflora of roasts stored in 100% O2, whereas lactic acid bacteria (Lactobacillus and Leuconostoc spp.) predominated on roasts after 1 week in all other atmospheres.

Physical and Sensory Characteristics of Pork Packaged in Various Gas Atmospheres

One hundred and ninety-six boneless pork roasts were vacuum-packaged. Twenty-eight roasts remained vacuum-packaged to serve as controls. The remaining packages were divided into six groups of 28 packages each and injected with one of six gas mixtures: (a) 100% O2, (b) 20% CO2 + 80% N2, (c) 50% CO2 + 50% O2, (d) 20% CO2 + 80% O2, (e) 25% CO2 + 25% O2 + 50% N2 or (f) 51% CO2 + 30% O2 + 18% N2 + 1% CO. Five packages from each packaging treatment were removed from storage after 7, 14, 21, 28 or 35 days. Data collection included gas composition of the intact packages and off-odor, surface discoloration, overall appearance, retail caselife and palatability of cuts. The most prevalent gas in vacuum packages was CO2 with weight percentages of 62–88% during the 35-day storage period. Packages initially injected with an atmosphere containing 100% O2 showed a gradual decrease in O2 and an increase in CO2 with increased storage. Roasts stored in O2-containing atmospheres for 14 and/or 21 days had a higher incidence of off-odor and chops from such roasts had lower overall appearance ratings after 1 day of retail display and lower flavor and overall palatability ratings than comparable vacuum packaged meats. These differences were significant only for roasts stored in modified atmospheres containing high concentrations of O2 and only after extended periods of storage. Data suggest that a modified gas atmosphere of 20% CO2 + 80% N2 is a suitable alternative to vacuum-packaging.

Microbiology of Beef Packaged in Various Gas Atmospheres

Boneless beef roasts (longissimus muscles) were vacuum-packaged and then the bags were injected with one of six gas mixtures: 100% O2, 20% CO2 +80% N2, 50% CO2 + 50% O2, 20% CO2 +80% O2, 25% CO2 + 25% O2 +50% N2 or 51% CO2 + 30% O2 + 18% N2 + 1% CO. One group of roasts, vacuum-packaged without added gas served as controls. Roasts were stored for 0–35 days at 1–3 C. At five weekly intervals, steaks were removed from roasts in each treatment and examined after storage for 5 days under retail display conditions. Psychrotrophic plate counts of roasts stored in modified gas atmospheres were usually higher than those stored in conventional vacuum packages. Differences in lactobacillus counts between roasts stored in modified gas atmospheres and those stored in vacuum packages rarely were statistically significant. Counts of retail steaks prepared from roasts stored in various gas atmospheres were usually slightly higher than those prepared from comparable vacuum packaged roasts. In most instances these differences were not statistically significant. Initially, the microbial flora of vacuum-packaged beef roasts consisted primarily of Moraxella-Acinetobacter and Pseudomonas spp. Lactobacilli predominated on roasts at later storage intervals even on roasts stored in atmospheres initially containing 100% O2 or 20% CO2 + 80% O2. Pseudomonas spp. remained a substantial part of the microflora of roasts stored in high O2 containing atmospheres.

Physical and Sensory Characteristics of Beef Packaged in Modified Gas Atmospheres

One hundred and ninety-six boneless beef roasts (longissimus muscles) were vacuum packaged. Twenty-eight roasts remained vacuum packaged to serve as controls while the remaining packages were injected with one of six gas mixtures: (a) 100% O2, (b) 20% CO2 + 80% N2, (c) 50% CO2 + 50%O2, (d) 20% CO2 + 80% O2, (e) 25% CO2 + 25% O2 +50% N2 or(f) 51% CO2 + 30% O2 + 18% N2 + 1% CO. Five cuts from each packaging treatment were stored in a 1-3-C cooler for 7, 14, 21, 28 or 35 days and subsequently evaluated for relative percentages of various gases in the intact packages, off-odor, surface discoloration. overall appearance, metmyoglobin percentages and palatability. Packages initially injected with modified gas atmospheres containing O2 increased in relative percentages of CO2 with advancing storage times. Roasts stored in modified atmospheres initially containing high levels of O2 exhibited a greater incidence of off-odor, more surface discoloration, lower overall appearance ratings, shorter retail caselife and lower overall palatability ratings than vacuum-packaged roasts or roasts stored in an atmosphere initially containing 20% CO2 + 80% N2.