Storage Characteristics of Brown Shrimp (Penaeus aztecus) Stored in Retail Packages Containing CO2-Enriched Atmospheres

The use of modified atmospheres containing CO₂ was effective in retarding microbial growth during refrigerated storage of retail packaged fresh brown shrimp (Penaeus aztecus). The inhibitory effcct seemed proportional to the CO₂ tension. The surface pH of shrimp stored in air increased rapidly during the initial storage period while a decrease in pH occurred in all the samples stored in CO₂-enriched atmospheres. Shrimp stored in modified atmospheres also had significantly lower total volatile nitrogen (TVN) values as compared to shrimp stored in air. Changes in the head-space composition were observed in all the atmospheres tested throughout the storage period, and were largest for shrimp stored in air.     

Changes in Sensory Quality of Sterile Cantaloupe Dice Stored in Controlled Atmospheres

Diced cantaloupe flesh that was microbiologically sterile was prepared to study the physiological deterioration of fruit when stored under a range of controlled atmospheres at 4.5°C. Sterile fruit pieces were prepared by boiling whole melons for 3 min, then dicing aseptically. Storage atmospheres were in continuous flow and contained from 0 to 26% CO₂ and 3.5 to 17% O₂. Sensory assessments were carried out by a highly trained panel at 14 day intervals. Acceptable product up to 28 days was obtained for three treatments: 6% CO₂ and 6% O₂, 9.5% CO₂ and 3.5% O₂, and 15% CO₂ and 6% O₂. Overall treatment with 0, 19.5 or 26% CO₂ (irrespective of O₂ concentration) caused significant deterioration in sensory characteristics.     

INCIDENCE OF MESOPfflLIC ANAEROBIC BACTERIA AND LACTIC ACID BACTERIA ON SLICED BREAD UNDER MODIFIED ATMOSPHERE PACKAGING DURING STORAGE

A total of 192 samples of sliced bread of different composition, water content and pH were selected to test the efficiency of modified atmospheres packing (MAP) on total mesophilic anaerobic bacteria and lactic acid bacteria (LAB) counts during MAB storage. The addition of calcium propionate and the storage temperature influenced significantly the counts. During most of the storage period at 15–20C, the concentration of O₂ was very low and that of CO₂ was constant or increased according to the atmosphere used. LAB counts increased in a significant way in the first week under CO₂ atmospheres. For the sliced bread, the highest counts were obtained under CO₂ atmospheres. In general, we consider that the presence/absence of calcium propionate added had a greater influence than the MAP conditions.     

Controlled‐atmosphere storage of tomato fruit: low oxygen or elevated carbon dioxide levels alter galactosidase activity and inhibit exogenous ethylene action

The effects of 3% O₂ and 20% CO₂, both alone and together with 100 µg g⁻¹ C₂H₄, on ethylene production, chlorophyll degradation, carotenoid biosynthesis and α‐ and β‐galactosidase activity in breaker tomato (Lycopersicon esculentum Mill) fruit were investigated. The low O₂ and high CO₂ atmospheres prevented the rise in ethylene production, total carotenoid and lycopene biosynthesis and α‐ and β‐galactosidase activity and slowed down chlorophyll degradation and loss of firmness (P < 0.05). These suppressive effects were not reversed, or only in part – in the case of chlorophyll breakdown – by addition of 100 µg g⁻¹ C₂H₄ to said controlled atmospheres. After transfer from the various atmospheres to air, flesh firmness decreased and ethylene production, total carotenoids, lycopene and β‐galactosidase II activity increased but these parameters were, in all cases, still significantly different from those of fruit held in air. Keeping tomatoes in controlled atmospheres, even in the presence of ethylene, had marked residual effects. Results suggest an antagonism between elevated CO₂/low O₂ and exogenous ethylene which could determine most of the ripening parameter behaviour under controlled‐atmosphere storage, though a direct regulatory mechanism by O₂ and/or CO₂ should not be discarded. © 1999 Society of Chemical Industry     

Atmosphere composition effects on Burlat cherry colour during cold storage

Carbon dioxide‐enriched atmospheres are used to reduce the incidence and severity of cherry decay and to extend postharvest life. Freshly harvested Burlat cherries were placed in jars at 5 °C for 10 days and ventilated with five different atmospheres: (a) air, (b) 12% CO₂–4% O₂, (c) 12% CO₂–20% O₂, (d) 5% CO₂–4% O₂, and (e) 5% CO₂–20% O₂. Samples were analysed when harvested and after 5 and 10 days of cold storage. Best results were obtained with cherries kept in high‐CO₂ atmospheres, independently of O₂ concentration. In these conditions the cherries present a higher acidity level (0.65 vs 0.60 g malic acid per 100 ml) and a lower anthocyanin content (0.40 vs 0.48 mg g^?1). As a consequence of this, h^* (18 vs 20.5) and C^* (24 vs 39) values are lower, which makes the cherries visually more reddish and less obscure and therefore more attractive for consumers. In addition, cherries kept in high‐CO₂ atmospheres present lower levels of peroxidase (469 vs 737 au g^?1) and polyphenoloxidase (73 vs 146 au g^?1) activities, which favours postharvest stability of colour. Copyright © 2004 Society of Chemical Industry     

Effect of Gas Atmosphere Packaging on Psychrotrophic Growth and Succession on Steak Surfaces

The influence of gas atmosphere packaging (1) 15% CO₂, 40% 0₂, 45% N₂; (2) 60% CO₂ 40% 0₂ (3) 10% CO₂, 5% 0₂, 85% N₂; (4) film overwrap (control) on the microbial growth and succession on steaks was studied during storage. Treatment 3 was most effective in reducing psychrotrophic growth on steaks. Pseudomonas species dominated the microflora for all packaging treatments during early storage. In all gas atmospheres. Serratia liquefaciens increased with storage time and the 10% CO₂ atmosphere showed the greatest increase. Enterobacter aerogenes appeared late in the storage period in all atmospheres and Yersinia enterocolitica was isolated after 12 days of storage from steaks in atmosphere 1.     

The sensory and microbiological quality of fresh sliced mushroom (Agaricus bisporus L.) packaged in modified atmospheres

The effect of modified atmospheres, generated by using different packaging films, on the quality of sliced mushrooms was evaluated. The carbon dioxide and oxygen content inside the packages as well as the colour, texture, weight loss, sensory attributes, mesophiles, psychrotrophs, Pseudomonas fluorescens, faecal coliforms, Escherichia coli and anaerobic spores were determined. Modified atmospheres containing 2.5% CO₂ and 10–20% O₂ reduced the microbial counts and improved the mushrooms’ appearance when compared with an air atmosphere. Modified atmospheres containing 15% CO₂ and <0.1% O₂ inhibited mushroom development and toughening and reduced microbial growth. Although these atmospheres had no effect on colour, they did allow the development of off odours and anaerobic spores were detected. No differences in microbial growth or mushroom spoilage were observed under the different moisture contents generated in the packages at 4 °C. Aerobic bacteria counts were considered very high even at the beginning.     

Adenine Nucleotide Degradation in Modified Atmosphere Chill-stored Fresh Fish

Effects of carbon dioxide modified atmospheres on degradation of adenine nucleotides in chill-stored whitefish (Coregonus clupeafor-mis) and rainbow trout (Salmo gairdneri) were studied. K values were determined during storage up to 26 days. Results indicated CO₂ atmospheres did not alter K values compared to those observed for aerobically held fish. However, both CO₂ atmospheres and potassium sorbate-dipping of fillets caused decreases in hypoxanthine concentrations compared to untreated aerobically held samples.     

Histamine Formation in Abusively Stored Pacific Mackerel: Effect of CO2-Modified Atmosphere

Whole Pacific mackerel (Scomber japonicus) were abusively stored at 20°C in air or 80% CO₂, balance air. Samples were analyzed for amines using a modified amino acid analyzer. Following 24 hr storage, levels of histamine, tyramine, putrescine, and cadaverine increased only slightly above the low levels observed initially. During the next 24 hr, the amine content increased dramatically. Levels in the air control samples were about twice those in the modified atmosphere samples. In a separate trial, amine levels in fish stored 3 days were higher still and similar in the two atmospheres. Thus, in neither trial did CO₂-modified atmosphere storage lead to increased production of potentially toxic amines.     

Supercritical CO2 Extraction of β-Carotene from Sweet Potatoes

Using supercritical CO₂ to extract β-carotene there was approximately a five-fold or a three-fold increase in amount of carotenoids extracted from freeze-dried tissue relative to the amount extracted from oven-dried or fresh tissue, respectively. The most efficient conditions were at 48°C and 41.4 MPa. Of the total carotenoid content ～20% was inaccessible to supercritical CO₂. The HPLC carotenoid profile of sweet potatoes showed that the unextracted tissue contained 90%β-carotene, primarily as all-trans (ca. 99%). Supercritical CO₂ extracts contained up to 94%β-carotene. The isomer composition of β-carotene of supercritical extracts showed ～ 14% 13-cis and 11% 9-cis.     

Sugars and Free Amino Acids in Stored Russet Burbank Potatoes Treated with CIPC and Alternative Sprout Inhibitors

Glucose, fructose, sucrose and free amino acids were measured in stored Russet Burbank potatoes treated with sprout inhibitors isopropyl-N-(3-chlorophenyl) carbamate (CIPC), 1,4-dimethylnaphthalene (DMN), cineole and salicylaldehyde. Storage effects on sugar and amino acid contents were dependent on the specific sprout inhibitor. Salicylaldehyde treatment (200 ppm) produced a rapid increase of reducing sugar content and a greater amount of free amino acids than other treatments. A smaller amount of tyrosine was found in DMN (40 ppm) treated tubers compared to all other treatments. After 16 wk at 7°C, all potatoes treated with inhibitors had 10.5–11.8 mg/g dry weight reducing sugar content which would be considered acceptable for French fry processing.     

Shelf-Life Extension of Fresh Ready-to-Bake Pizza by the Application of Modified Atmosphere Packaging

Combined effects of modified atmosphere packaging (MAP) and refrigeration (7±1 °C) were studied on shelf-life extension of ready-to-bake pizza. The gas atmospheres in the present study included four variables, namely viz. MAP1, air (control); MAP 2, 100% CO₂; MAP 3, 100% N₂; and MAP 4, 50%CO₂/50%N₂. The effect of MAP variables was observed for moisture content, water activity, pH, titratable acidity, free fatty acids, peroxide value, thiobarbituric acid, tyrosine content, lycopene content and L* a* b* values. The results indicated that MAP with 100% CO₂ significantly inhibited the lipid oxidation, reduced proteolysis and prevented total acidity (less decrease in pH). Also, the MAP (MAP 2) showed preservative effect on colour indices and shelf life higher than other treatments. Sensory analysis showed that the control samples had a limited shelf life of 5 days while a significant increase in shelf life of 15 days (300% increase) was achieved under modified atmospheres for unbaked pizza samples.     

Effects of atmospheric composition on respiratory behavior, weight loss, and appearance of Camembert-type cheeses during chamber ripening

Respiratory activity, weight loss, and appearance of Camembert-type cheeses were studied during chamber ripening in relation to atmospheric composition. Cheese ripening was carried out in chambers under continuously renewed, periodically renewed, or nonrenewed gaseous atmospheres or under a CO₂ concentration kept constant at either 2 or 6% throughout the chamber-ripening process. It was found that overall atmospheric composition, and especially CO₂ concentration, of the ripening chamber affected respiratory activity. When CO₂ was maintained at either 2 or 6%, O₂ consumption and CO₂ production (and their kinetics) were higher compared with ripening trials carried out without regulating CO₂ concentration over time. Global weight loss was maximal under continuously renewed atmospheric conditions. In this case, the airflow increased exchanges between cheeses and the atmosphere. The ratio between water evaporation and CO₂ release also depended on atmospheric composition, especially CO₂ concentration. The thickening of the creamy underrind increased more quickly when CO₂ was present in the chamber from the beginning of the ripening process. However, CO₂ concentrations higher than 2% negatively influenced the appearance of the cheeses.     

Effect of packaging atmosphere and pH on the virulence and growth ofYersinia enterocoliticaon pork stored at 4°C

Growth and virulence of pathogenicYersinia enterocoliticawere investigated on high (pH>6.0) and normal (pH<5.8) pH pork packaged in modified atmospheres and stored at 4°C. Modified atmospheres used in the study were vacuum packaging and saturated CO₂. Pork was packaged in a high gas barrier packaging film and examined over a 30-day period. Phenotypic characteristics were used to detect the presence of the virulence plasmid ofY. enterocoliticaafter exposure to the pork packaging and storage regimen. Phenotypic characteristics ofY. enterocoliticaisolates from pork loin stored at 4°C for 30 days that were studied included Congo red uptake, calcium dependence and autoagglutination in methyl red Voges–Proskauer broth and tissue culture medium. Numbers ofY. enterocoliticaon the lean surface of high pH pork slices increased approximately 2.7logcfucm⁻²when vacuum packaged and stored at 4°C for 30 days. Storage of inoculated normal pH pork in 100% CO₂resulted inY. enterocoliticaremaining in the lag phase over the storage period. Virulence ofY. enterocoliticawas maintained in 25 to 35% of isolates following storage for 30 days at 4°C in vacuum- and CO₂-packaged meats and was not affected by pH of the pork loin.     

Growth/survival of natural flora and Aeromonas hydrophila on refrigerated uncooked pork and turkey packaged in modified atmospheres

To evaluate the growth/survival of natural flora and Aeromonas hydrophila on refrigerated normal low (pork) and high (turkey) pH meats packaged in modified atmospheres, A. hydrophila was inoculated onto fresh pork and turkey meat slices. Inoculated and control samples were packaged in modified atmospheres (100% N₂, 20/80 and 40/60 CO₂/O₂) or in air in plastic bags and kept at 1 and 7°C. Samples packaged in air showed a similar microbiological pattern to that usually observed in fresh meat stored aerobically. Packaging in modified atmosphere produced a strong inhibition of bacterial growth at 1°C, particularly in samples stored in CO₂/O₂enriched atmospheres. Aeromonas hydrophila grew on turkey and pork meat stored in 100% N₂at 1 and 7°C. Likewise, growth of this bacterium was detected on turkey stored in 20/80 CO₂/O₂at 7°C. No growth was observed in 40/60 CO₂/O₂in any meat at both temperatures assayed.     

Modified atmosphere storage to prevent mould-induced nutritional loss in maize

Effect of modified atmosphere storage systems having 60% CO₂, 40% CO₂ and 20% CO₂ in combination with N₂ and O₂ were studied on freshly harvested maize grain (var Deccan-103) to prevent moulding and loss of food reserves. Under favourable conditions of 90% relative humidity and at 25±2°C, maize grains having 15 and 20% moisture content stored for 45 days revealed significant postponement of visible moulding and the loss of food reserves. The results showed that, maize grain with 15% moisture content does not support mould growth even after 45 days of storage, as a result loss of food reserves reduced considerably. Visible moulding was postponed by 15 days under 60% CO₂ and 40% CO₂ atmospheres in grains with 20% moisture contents and the loss of food reserves in MAS treated samples were significantly reduced over the untreated maize grains. Dry matter loss (DML) was also significantly reduced under 60% CO₂ modified atmospheres in maize grains with 20% moisture content. © 1998 SCI.     

Controlled atmosphere storage of pomegranate

Pomegranates cv. Mollar were stored for up to 8 weeks at 5 °C and above 95% relative humidity (RH) in air and in controlled atmospheres of 10% O₂ and 5% CO₂, 5% O₂ and 5% CO₂, 5% O₂ and 0% CO₂ and 5% O₂ and 0% CO₂ ethylene-free. Storage was followed by a shelf-life period of 6 days at 20 °C in air. Respiratory activity slightly declined during storage at 20 °C, from 12 to 8 ml CO₂ · kg^–1 · h^–1 and was around 4 ml CO₂ · kg^–1 · h^–1 at 5 °C showing a non-climacteric pattern. When compared with color at harvest, an increase in thea ^* value in the juice from pomegranates stored in 10% O₂ and 5% CO₂ was observed. This supports that view that juice red colour can increase in intensity during storage. Controlled atmosphere storage reduced weight loss, the risk of decay and the severity of husk scald (except at 10% O₂ and 5% CO₂). The relatively low control of husk scald at 5% O₂ disagrees with the level proposed previously for Wonderful cv.; Mollar cv. seems to be more sensitive to scald than other varieties. No symptoms of black spots or membranose and no off-flavours were detected at any time. However after a period of shelf-life storage, the controlled atmosphere caused a slight reduction (lower than in air-stored fruit) in titratable acidity, reducing sugars and vitamin C and an increase of the soluble solids content/titratable acidity (maturity index) without differences among the various gas compositions studied. The maturity index must be considered to be a good criterion of pomegranate maturity for sweet varieties.     

STORAGE OF MINIMALLY PROCESSED ROMAINE LETTUCE UNDER CONTROLLED ATMOSPHERE

The effects of CO₂ and O₂ concentration on the preservation of minimally processed Romaine lettuce (Lactuca sativa, L.) under controlled atmosphere were studied. The lettuce was stored at 4C for 16 days under a continuous stream of nitrogen containing 0.5 to 2% O₂ and 2 to 15% CO₂. Increasing the CO₂ content in the atmosphere to 10% or more reduced enzymatic browning due to wounding and improved lettuce visual quality. However, 15% CO₂ caused brown lesions (brown stain, BS) after 8 days of storage. Decreasing the O₂ content to 1% in the presence of 10% CO₂ reduced tissue browning slightly without lowering the content of phenols, but 0.5% O₂ increased browning and anaerobiosis. Among the atmospheres tested, 10% CO₂ and 1% O₂ were beneficial for maintenance of the quality of minimally processed Romaine lettuce.     

SHORT-TERM CONTROLLED ATMOSPHERE STORAGE FOR SHELF-LIFE EXTENSION of APRICOTS1

Shelf-life of ‘Perfection’ and ‘Rival’ apricots can be enhanced with the use of controlled atmosphere (CA) storage. Apricots were harvested at commercial maturity and immediately stored in CA at 1 or 2% 0₂ and 3, 6, 9, 12 or 15% C0₂ for 30, 45 and 60 days. No differences in fruit quality were evident between 02 atmospheres of 1 and 2%, except that fruit stored in 1 % 02 displayed less rot development and higher acid content. Apricots stored in 9% or less C0₂ displayed reduced external and internal color, inadequate finish, increased internal breakdown and more rot development with unacceptable firmness retention for additional handling. Apricots stored in 12 or 15% CO₂ retained firmness and displayed enhanced finish with reduced rots and very little internal breakdown with storage duration of 60 days. Color was much slower to develop in apricots stored in 12 or 15% CO₂ for all storage periods.     

Effects of packaging type, gas atmosphere and storage temperature on survival and growth of Listeria spp. in shredded dry coleslaw and its components

The survival and growth of Listeria populations inoculated on to dry coleslaw mix and its components were investigated, focusing on effects of storage temperatures and gas atmospheres within packaging films or storage chambers. There were few significant effects of packaging film at 3 °C, but at 8 °C the elevated CO₂/low O₂ atmospheres generated within orientated polypropylene (OPP) packages and used in controlled atmosphere chambers were inhibitory. Although two strains of Listeria monocytogenes had survival characteristics comparable with Listeria innocua, L. monocytogenes ATCC 19114 survived better at 3 °C and also in the elevated CO₂/low O₂ atmospheres within OPP at 8 °C. The effects of product components on the survival of L. innocua were linked to storage temperature. Shredded carrot reduced initial counts and at 8 °C inhibited survival of L. innocua in comparison with shredded cabbage.