Effect of Modified Atmosphere Packaging on Shelf-Life of Iced Fresh Hake Slices

Shelf-life of hake slices (Merluccius merluccius) stored in the ice state (2±1°C) under modified atmosphere packaging (MAP) conditions was determined by measurements of pH, total volatile bases (TVB) and trimethylamine (TMA) content, mesophilic and psychrophilic bacterial counts, malonaldehyde content, exudation, protein functionality and sensorial analyses (colour and odour). The effect of different gas mixtures were evaluated: (1) 40% CO₂, 50% N₂, 10% O₂; (2) 60% CO₂, 30% N₂, 10% O₂; (3) 40% CO₂, 30% N₂, 30% O₂; (4) 60% CO₂, 10% N₂, 30% O₂ and (5) air (control). Important differences were found between MAP-stored and air-stored hake slices. Shelf-life of hake stored under MAP conditions was two-fold extended. Bacterial growth wasinhibited, increases of pH, TMA and TVB were reduced, and alterations inprotein functionality were delayed, and off-odours were not noted in MAP-stored hake slices after 21 days storage. Significant correlations were found between TMA content and total viable count (TVC), as well as between apparent viscosity and exudation. Hake slices could be stored in the ice state under MAP conditions for about three weeks without an important loss of quality. Fish freshness, handling practices and initial bacterial load have an important influence of shelf-life of hake.     

Different MAP conditions to improve the shelf life of sea bass

Shelf life of cultured sea bass packaged in air, vacuum, and gas mixture packages stored for 40 days at 2.90±0.02°C was compared. The gas mixtures used contained CO₂, O₂, and N₂ at difference percentages (M1: 75% CO₂/25% N₂; M2: 60% CO₂/40% N₂; M3: 30% O₂/30% CO₂/40% N₂). Sensory and physical parameters, chemical changes, and microbiological counts were monitored during storage. Storage with a gas mix including 75 and 60% CO₂ was more effective than vacuum processing and packaging with a gas mix that included oxygen. Vacuum was the most effective method for preventing lipid oxidation. The optimum method for sea bass in view of all analysis results was modified atmosphere packaging (MAP) and the most suitable gas mix ratio was 75% CO₂/25% N₂. The best days for consumption of sea bass packaged with air, MAP (M1, M2, and M3), and vacuum were 4^th, 28^th, 28^th, 16^th, and 20^th days, respectively.     

Residual effect of CO2 on hake (Merluccius merluccius L.) stored in modified and controlled atmospheres

 The residual effect of CO₂ on whole gutted hake kept with three different CO₂/O₂/N₂ gas mixtures: 60/15/25, 80/20/0 and 40/40/20, and two different kinds of atmospheres (controlled and modified) during 12 days followed by conventional storage in ice for up to 30 days was examined by physical, chemical and sensory analyses. Shelf life was longer in lots kept in atmospheres than in control lots and was further prolonged by controlled than by modified atmospheres. The lots kept in the atmosphere with the highest concentrations (80%) of CO₂ exhibited the lowest trimethylamine nitrogen and total volatile basic nitrogen values. However, these were also the lots that scored worst in sensory analysis. The lots that scored best in sensory analysis were those which were kept in the gas mixtures with 60% and 40% of CO₂. Oxidative rancidity was not a problem in the samples stored in the atmosphere with 40% O₂; Thiobarbituric acid levels were lower than 2 mg/100 g in all lots throughout storage, and the assessors detected no rancidity. The residual effect of CO₂ on whole gutted hake was more effective in controlled atmosphere lots. Received: 15 June 2000 / Revised version: 17 August 2000     

Shelf‐Life Extension of Chill‐Stored Beef Longissimus Steaks Packaged under Modified Atmospheres with 50% O2 and 40% CO2

This study was conducted to compare the shelf‐life of beef steaks stored in different packaging conditions: overwrapped (OW) packaging and 2 modified atmosphere packaging systems (MAP): 80% O₂ MAP (80% O₂/20% CO₂) and 50% O₂ MAP (50% O₂/40% CO₂/10% N₂). Steaks were stored at 2 °C for 20 d. Headspace gas composition, microbial counts, color stability, pH, purge loss, and lipid oxidation were monitored. Among the packaging types, 50% O₂ MAP was superior to OW packaging and 80% O₂ MAP in delaying bacterial growth and extending shelf‐life to 20 d. 50% O₂ MAP also gave steaks an acceptable color during storage. No significant differences were observed in color stability of steaks packaged in both 50% O₂ MAP and 80% O₂ MAP. This study reveals 50% O₂ MAP is a realistic alternative to preserve beef steaks efficiently.     

Storage Quality Characteristics of Beef Rib Eye Steaks Packaged in Modified Atmospheres

Microbiological, chemical, physical and sensory attributes of beef rib eye steaks packaged in air, vacuum or combinations of %O₂-%CO₂ (10–20, 20–20, 10–40, 20–40), were examined during storage at 2°–4° C. Modified atmosphere (MAs) changes over time were measured. Oxygen concentration decreased while CO² increased during storage, for all MAs. Vacuum was superior to MAs in delaying bacterial growth other than that of Enterobacteriaceae, in protecting beef color and lipids against oxidation and in maintaining sensory attributes in steaks. MAs were superior to packaging in air for all parameters tested, and to vacuum only in that Enterobacteriaceae were strongly inhibited, purge losses decreased by 50% and cooking yields increased. High-CO² MAs (40%) did not impair beef color, but CO² promoted lipid oxidation. Volatile basic nitrogen (VBN) did not indicate beef freshness.     

Shelf-life extension and quality attributes of the whey cheese “Myzithra Kalathaki” using modified atmosphere packaging

The present work evaluated the effect of modified atmosphere packaging (MAP) on quality characteristics and shelf-life extension of the whey cheese “Myzithra Kalathaki” using microbiological, chemical and sensory analyses. Myzithra cheese was packaged in four different atmospheres: vacuum, 20% CO₂/80% N₂ (M₁), 40% CO₂/60% N₂ (M₂) and 60% CO₂/40% N₂ (M₃); identical cheese samples were packaged in air, taken as controls. All cheese samples were kept under refrigeration (4±0.5 °C) for 45 days. Of the four atmospheres, the M₂ and M₃ gas mixtures were the most effective for inhibiting growth of aerobic microflora and psychrotrophs in cheese samples until days 40 and 33 of refrigerated storage, respectively. Lactic acid bacteria (LAB) were part of the cheese microflora becoming dominant toward the end of the storage period regardless of packaging conditions. Enterobacteriaeceae were also part of the cheese microflora being effectively inhibited after day 35 of storage. Molds and yeasts were also totally inhibited by MAP (M₂ and M₃) gas mixtures throughout the entire storage period. Of the chemical quality indices determined, lipid oxidation varied below 0.005 absorbance at 532 nm for all treatments, except control samples for which absorbance values of 0.02 were recorded after 35 days of storage. Lipolysis did not vary significantly with type of packaging treatment while proteolysis values showed and increasing trend up to day 25 of storage and then decreased toward the end of the storage period. Sensory evaluation (odour and taste) showed that Myzithra cheese packaged under MAP (M₂ and M₃) retained good sensory characteristics for 30 days of storage while control samples were sensorily unacceptable after 10-12 days of storage.     

Microbial and physicochemical modifications of hake (Merluccius merluccius) steaks stored under carbon dioxide enriched atmospheres

Microbial counts (total viable, Brochothrix thermosphacta, lactic acid bacteria and Enterobacteriaceae), biochemical parameters [pH, total volatile nitrogen, nucleotide breakdown products, non‐volatile amines, D (−) and L (+) lactic acid and short‐chain fatty acids] and sensory attributes (colour and odour) of refrigerated (2 °C) hake (Merluccius merluccius) steaks under carbon dioxide enriched air (CO₂ /air, 20/80 v/v and CO₂ /air, 40/60 v/v) and air atmospheres were determined. When compared with air, sensory results showed shelf‐life extension of 4 and 11 days for 20% and 40% CO₂‐enriched atmospheres, respectively. Microbial and biochemical results also revealed that the 40% CO₂‐enriched atmosphere was the most effective packaging type for refrigerated hake. © 2000 Society of Chemical Industry     

Use of carbon dioxide enriched atmospheres in the refrigerated storage (2 °C) of salmon (Salmo salar ) steaks

 Selected microbial counts (total viable microbiota, Brochothrix thermosphacta, lactic acid bacteria and Enterobacteriaceae), biochemical parameters [pH, total volatile nitrogen, nucleotide breakdown products, non-volatile amines, d(–) and l(+)-lactic acids and short-chain fatty acids] and sensory attributes (colour and odour) of refrigerated (2  °C) salmon (Salmo salar) steaks stored under CO₂-enriched [CO₂/air (20/80, v/v), CO₂/air (40/60, v/v)] and air atmospheres were determined. When compared with air, sensory results showed shelf-life extension of 6 days and 15 days for 20% and 40% CO₂-enriched atmospheres, respectively. Microbial and biochemical results also revealed that the 40% CO₂-enriched atmosphere was the most effective packaging type for refrigerated salmon. Received: 22 April 1999     

Combined effects of thymol, carvacrol and temperature on the quality of non conventional poultry patties

The combined effect of thymol (0–300 ppm), carvacrol (0–300 ppm), and temperature (0–18 °C) on the quality of non conventional poultry patties packaged in air and modified atmosphere (MAP: 40% CO_2; 30%O₂; 30% N₂) was investigated using a simplex centroid mixture design. The patties were monitored for microbiological (total viable count, Enterobacteriaceae, lactic acid bacteria, Pseudomonas spp.) physico-chemical (pH, colour) and sensory attributes. For the patties mixed with the antimicrobials and stored at low temperature (0–3 °C) a reduction of the cell load of about 1–1.5 log cfu/g was observed. The log reduction was lower at the end of storage time and decreased with the increase of the temperature. For the poultry patties packaged in MAP the higher log reduction for Pseudomonas spp. during all the storage time was observed. In both packaging atmospheres the combination of the essential oils and low temperature determined no modification for off-odour during the first 4 days of storage.     

Effect of modified atmosphere and vacuum packaging on some quality characteristics and the shelf-life of “morcilla”, a typical cooked blood sausage

The effect of modified atmosphere and vacuum packaging on the shelf-life of “morcilla”, a traditional cooked blood sausage, was investigated. A total of 99 “morcillas” were packaged under vacuum and in modified atmosphere using three different gas mixtures: 15:35:50/O₂:N₂:CO₂ (atmosphere 1), 60:40/N₂:CO₂ (atmosphere 2) and 40:60/N₂:CO₂ (atmosphere 3), and stored during 2, 4, 6 and 8 weeks at 4 °C. Shelf life evaluation was based on pH, water activity (a_w), colour (CIE L*, a*, b*, C* and h*), TBARS formation and microbial counts. The results indicated that, in general, storage time affected (P < 0.05) all parameters whereas no significant differences were observed (P > 0.05) among packaging conditions. Based on the microbial counts, the shelf-life of “morcilla” would be greater than 8 weeks for all packaging conditions. Samples packaged with high CO₂ concentrations (40:60/N₂:CO₂) showed the lowest values of TBARS at the end of storage.     

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.     

Scandinavian consumer preference for beef steaks packed with or without oxygen

Beef steaks retail-packed with (80% O₂, 20% CO₂) or without oxygen (either skin-packed or gas-packed (69.6% N₂, 30% CO₂, 0.04% CO or 70% N₂, 30% CO₂)) were compared by consumers in Denmark (n = 382), Norway (n = 316) and Sweden (n = 374). Two pairs of two steaks – one steak packed in a high oxygen atmosphere and one packed without oxygen – were given to the consumers. They were instructed to prepare the steaks at home on two consecutive days, and two persons had to taste each steak. In Denmark, the oxygen-free packing was either gas packing with CO (69.6% N₂, 30% CO₂, 0.04% CO) or without CO (70% N₂, 30% CO₂), in Norway it was either gas packing with CO (69.6% N₂, 30% CO₂, 0.04% CO) or skin packing, and in Sweden it was either skin packing or gas packing without CO (70% N₂, 30% CO₂). The meat represented animals that were between 17 and 80 months old (Denmark) and young bulls (Norway and Sweden).     

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.     

Survival and Growth of Listeria monocytogenes and Yersinia enterocolitica in Pork Chops Packaged under Modified Gas Atmospheres

Listeria monocytogenes Scott A, serotype 4b, and Yersinia enterocolitica from vacuum-packaged pork were inoculated onto fresh pork chops. Survival and growth were determined in different atmospheres at 4 °C during 35-days. Atmospheres were gas mixtures [20/0/80, 40/ 0/60, and 40/10/50 (CO₂/O₂/N₂)], vacuum and air. In air L. monocytogenes and Y. enterocolitica grew slower than psychrotrophic spoilage flora. In gas atmospheres, Y. enterocolitica grew at the same rate as psychrotrophic spoilage flora and L. monocytogenes grew more slowly. When 10% O₂ was included in the 40% CO₂ mixture, growth was reduced. Vacuum packaging was no more effective than gas mixtures in retarding growth. Modified atmospheres provide an environment in the package that would allow growth of Y. enterocolitica and potentially compromise safety of meat products.     

Effect of controlled atmosphere storage on aflatoxin production in high moisture peanuts (groundnuts)

Shelled peanuts (groundnuts) remoistened to 16.7% were stored for 4 weeks at about 27°C in air (0.03% CO₂, 21% O₂, 78% N₂) and in three modified atmospheres: (1) 13.6% CO₂, 0.3% CO, 0·6% O₂, 84.7% N₂; (2) 12.2% CO₂, 3.1% CO, 0.3% O₂, 83.5% N₂; and (3) 13.6% CO₂, 0.1% CO, 1.5% O₂, 83.9% N₂. Aflatoxins, per cent free fatty acids, and per cent kernel infection by the Aspergillus flavus group were determined weekly. Peanuts in air and in the atmosphere containing 1.5% O₂ accumulated high levels of aflatoxin in 1 and 2 weeks, respectively. In the other two controlled atmospheres aflatoxin B₁ did not exceed 21 μg/kg and the per cent of free fatty acids increased only slightly. None of the treatments eliminated infection by the A. flavus group. After 4 weeks peanuts in all treatments had visible fungal growth on surfaces.     

Colour of hot paprika from the La Vera and Murcia regions packaged in different atmospheres during storage

This study compared the behaviour of hot paprika (Capsicum annuum L.) samples from the district of La Vera and the region of Murcia packaged in five different conditions during storage. The following five different packaging conditions were used in this study: modified atmosphere packaging with three different conditions (100% N₂; 50% N₂ and 50% CO₂; and 100% CO₂), vacuum packaging and traditional packaging (product packaging system without modifying the atmosphere). After the samples were packaged, they were stored for 8 months at room temperature (normal storage conditions). The following parameters were used to indicate the quality of the samples: Aw, ASTA colour, CIE_L*a*b* colour parameters, and the composition of red and yellow compounds. The results indicate that the modified atmosphere packaging and vacuum packaging exerted a protective effect on the paprika quality characteristics regardless of the paprika origin. However, no clear differences were detected between the effect of vacuum packaging and the different modified atmosphere packaging conditions.     

Potential mechanisms of carbon monoxide and high oxygen packaging in maintaining color stability of different bovine muscles

The objectives were to compare the effects of packaging methods on color stability, metmyoglobin-reducing-activity (MRA), total-reducing-activity and NADH concentration of different bovine muscles and to explore potential mechanisms in the enhanced color stability by carbon monoxide modified atmosphere packaging (CO-MAP, 0.4% CO/30% CO₂/69.6% N₂). Steaks from longissimus lumborum (LL), psoas major (PM) and longissimus thoracis (LT) packaged in CO-MAP, high-oxygen modified atmosphere packaging (HiOx-MAP, 80% O₂/20% CO₂) or vacuum packaging were stored for 0 day, 4 days, 9 days, and 14 days or stored for 9 days then displayed in air for 0 day, 1 day, or 3 days. The CO-MAP significantly increased red color stability of all muscles, and especially for PM. The PM and LT were more red than LL in CO-MAP, whereas PM had lowest redness in HiOx-MAP. The content of MetMb in CO-MAP was lower than in HiOx-MAP. Steaks in CO-MAP maintained a higher MRA compared with those in HiOx-MAP during storage. After opening packages, the red color of steaks in CO-MAP deteriorated more slowly compared with that of steaks in HiOx-MAP.     

Preservation of precut white cheese by modified atmosphere packaging

Effects of modified atmosphere packaging (MAP) on storage stability and quality of precut fresh and aged white cheese were investigated. Fresh or aged white cheese was cut into small cubes and packaged in five different atmospheres [0% O₂ + 0% CO₂ + 100% N₂ (MAP1), 10% O₂ + 0% CO₂ + 90% N₂ (MAP2), 0% O₂ + 75% CO₂ + 25% N₂ (MAP3), 10% O₂ + 75% CO₂ + 15% N₂ (MAP4) and aerobic (air)]. Control samples were packaged in brine and vacuum for fresh and aged white cheese, respectively. Changes in gas composition, total plate count, lactococci, lactobacilli, yeast and mould counts, proteolysis, lipolysis, pH, colour, texture and sensory properties were investigated during refrigerated storage. The best packaging treatment for the fresh cheese was MAP3, as it inhibited mould growth and protected the hardness. MAP2 can be recommended for the packaging of the aged cheese, as it decreased lipolysis.     

Effects of modified atmosphere and vacuum packaging on the growth of spoilage and inoculated pathogenic bacteria on fresh poultry

Fresh chicken breast meats inoculated withYersinia enterocolitica andAeromonas hydrophila were packaged in glass jars either containing different compositions of modified atmospheres (MA) (100% CO₂; 80% CO₂/20% N₂), or in vacuo or containing air, and were stored at 3±1°C and 8±1°C. The changes in gas composition as well asY. enterocolitica, A. hydrophila, total aerobic bacterial, total psychrotrophic, Lactobacilli and Enterobacteriaceae counts were determined after 0,1,3,7,9,11 and 14 days of storage. The results show that while the growth ofY. enterocolitica andA. hydrophila were retarded following MA storage, the pathogens were capable of growth in MA and vacuum storage at both temperatures, for the inoculation levels studied. For total aerobic bacterial counts, there were no differences between the values for chicken breast meats kept in different atmospheres. Being packaged in CO₂ had the greatest inhibitory effect on the growth of psychrotrophic aerobic bacteria during the first 3 days. Lactic acid bacteria levels of samples stored in MA conditions and in vacuo increased rapidly when compared to those levels of samples stored in air. It was also found that the effect of MA storage increased at 3±1°C.     

Modified atmosphere influences aflatoxin B1 contamination and quality of peanut (Arachis hypogaea L.) kernels cv. Khon Kaen 84-8

Storage of ‘Khon Kaen 84-8’ peanut kernels in laminated bags (Low density polyethylene (LDPE)/Nylon) (20×30 cm; 120 μm thickness) under different packaging atmospheres had effect on quality, fungal occurrence and aflatoxin B₁ (AFB₁) contamination. During fifteen week storage, peanuts (6.4% moisture content) were kept under different packaging atmospheres with some inoculated (Inoc.) and without (Non-Inoc.) aflatoxin producing fungus Aspergillus flavus. The treatments include; 100% CO₂+Inoc., 100% N₂+Inoc., vacuum + Inoc., Air + Inoc., and Air + Non-Inoc. packed with only ambient air. The storage room conditions were a temperature of 29±2 °C and 70 ± 5% r. h. Mycobiota occurrence, AFB₁ level, moisture content, lipase activity, free fatty acids and rancidity (Thiobarbituric acid; TBA value) were investigated. A total of five major fungi were identified with four storage fungi and one field fungus; Rhizopus stolonifer, Aspergillus niger, A. flavus, Penicillium spp., and Fusarium spp., respectively. Packaging in 100% CO₂+Inoc. significantly repressed the fungal occurrence especially A. niger while all other packaging atmospheres suppressed proliferation of both R. stolonifer and Penicillium spp. The peanuts kept in vacuum + Inoc. package revealed AFB₁ level below detection limit (0.4 μg/kg). Peanut kernels in 100% CO₂+Inoc. packaging atmosphere maintained an acceptable color indicated by L* and a* values, as well as the color change (ΔE) compared to other treatments. Different packaging atmospheres showed variable results in relation to the free fatty acids level with packaging under 100% N₂ revealing the lowest. Subsequently, 100% N₂ packaging atmosphere relatively inhibited rancidity occurrence in peanut kernels during storage. The results of this study portray that 100% CO₂, 100% N₂ and vacuum packaging atmosphere could have a potential to suppress occurrence of mycobiota, maintain peanut kernel quality in relation to color and lipid oxidation, and as well curtail AFB₁ contamination respectively, for fifteen weeks or more given the quality of kernels at the end of storage.