Shelf Life of Fresh Beef Stored in Master Packages with Carbon Monoxide and High Levels of Carbon Dioxide

Beef steaks from Gluteus medius, Longissimus dorsi, Psoas major and ground beef from Triceps brachii were packed in master packages containing expanded polystyrene trays overwrapped with polyvinyl chloride film under an anoxic atmosphere containing 0.2% CO, 60.0% CO₂ and 39.8% N₂ (T₁) or 0.2% CO/99.8% CO₂ plus oxygen scavengers. After 28 days of storage at 1 and 4°C, the meat quality was evaluated. The visual and instrumental colour of the beef steaks and ground beef were similar to that of fresh meat. Pathogenic bacteria were not detected, and psychrotrophic bacterial counts were lower than 7.5 log CFU/g. Copyright © 2012 John Wiley & Sons, Ltd.     

Effect of different modified atmosphere packaging on microbial quality,oxidation and colour of a seasoned ground beef product (meatball)

The effects of different modified atmosphere packaging (MAP) on microbial quality, oxidation and colour of meatballs were investigated. Meatballs were prepared in our laboratory and packaged in vacuum or in different gases: combinations of O₂ (0, 2, 21%) and CO₂ (0, 33, 66, 100%) with N₂ as balance gas. Total microbial count, thiobarbituric acid reactive substances and colour were determined during storage at 3°C for 3 weeks. Total microbial count remained unchanged at around 6.3 LogCFU/g in vacuum and 100% CO₂ packages after 7 days, and slightly increased afterwards. The microbial count was higher in other packages and increased to 7.6 LogCFU/g after 21 days storage. Oxidation was inhibited by reduced O₂ and increased CO₂ in the packages. Packages with low O₂ maintained colour (a‐values) to a greater extent than the packages with higher O₂ levels. MAP containing 1–3%O₂ with 33%CO₂ inhibited microbial growth, oxidation and colour change in meatballs. Copyright © 2009 John Wiley & Sons, Ltd.     

Preservation of freshness of rainbow trout fillets packaged with carbon dioxide-nitrogen gas mixture (studies on gas-exchange packaging of fresh fish,part 2)

Gas-exchange packaging was applied to preserve freshness of rainbow trout fillets. The fillets were packaged in pouches of coextruded laminate (ethylene vinyl acetate/ polyvinylidene chloride-polyolefin) with a carbon dioxide-nitrogen gas mixture (N₂ : CO₂ = 6 : 4). Other fillets were wrapped with polyvinyl chloride film as a reference group. Changes in sensory score of colour and flavour, K-value and bacterial counts of the fillets were investigated during storage at 5°C. After 2 days the fillets wrapped with polyvinyl chloride film lost their gloss. In addition, an amine-like odour was detected after 3 days. The gas-packaged fillets, however, showed little change in colour, flavour and bacterial counts, and retained their fresh appearance for 3 days.     

Effects of active modified atmosphere on lipid and protein oxidation,moisture migration and quality properties of beef steaks

Fresh beef is a typically perishable food because of its high water and protein content; thus, it requires proper packaging condition and storage temperature to ensure its quality. In this study, the beef steaks were stored at 4°C under HiO₂ modified atmosphere packaging (MAP) (78.8% O₂ + 18.8% CO₂ + 2.4% N₂) and HiCO₂ MAP (60.0% CO₂ + 40.0% N₂). The traditional air packaging (AP) and vacuum packaging (VP) were used as the controls. The total viable count (TVC), colour, water holding capacity (WHC), myofibrillar protein (MP) oxidation and lipid oxidation of beef meat were investigated. The moisture distribution and migration were also analysed using the low-field nuclear magnetic resonance (LF-NMR). The association amongst all parameters was analysed by correlation analysis and principal component analysis (PCA). The results showed that the TVC values in the HiCO₂ MAP (5.6 log CFU/g) steaks were lower than those of VP (5.9 log CFU/g), AP (7.0 log CFU/g) and HiO₂ MAP (6.3 log CFU/g) steaks because of the sufficient CO₂ after 15 days of chilled storage. The bright red colour and the higher WHC were maintained in the HiO₂ MAP steaks than in the AP group during storage. However, higher levels of protein and lipid oxidation also occurred. The beef steaks stored under HiCO₂ MAP had the lowest protein and lipid oxidation and highest value of immobile water content and WHC, however, similar to the VP group, the bright red colour was not shown. The moisture attributes (drip loss, cooking loss and P₂₃), protein oxidation (protein solubility and carbonyl content) and lipid oxidation (TBARS value) have shown a close correlation by correlation analysis and PCA. Overall, two different packaging methods of MAP can prolong microbial-shelf life and maintain higher WHC of beef steaks compared to AP and VP steaks, but higher oxidation level in HiO₂ MAP and unattractive colour in HiCO₂ MAP are concerns that need to be addressed.     

Effect of packaging materials and storage conditions on bacterial growth,off‐odour,pH and colour in chicken breast fillets

A comparison was made of the effect of different packaging materials on bacterial growth, off‐odour, pH and colour of chicken breast fillets stored at 4°C. For one of the packaging materials, the effects of temperature (4°C and 8°C) and initial oxygen present (0%, 2% and 4%) on bacterial growth, off‐odour, pH and colour in chicken breast fillets were also evaluated. Chicken breast fillets stored in the packaging material with the highest oxygen transmission rate (OTR) measured at actual storage conditions had the highest bacterial growth and the highest degree of off‐odour. Chicken breast fillets stored in packaging material mainly consisting of expanded PET had similar bacterial growth and off‐odour as in the barrier display film (BDF) packages, despite a smaller headspace volume and lower initial concentration of CO₂. No differences in discoloration and pH of the chicken breast fillets, due to storage temperature and amount of initial oxygen present, were found when one of the packaging materials was studied. In the early phase of the storage period, Pseudomonas spp. constituted the majority of the total viable counts, while after about 12 days, lactic acid bacteria dominated. At the end of the storage period, both Pseudomonas spp. and Enterobacteriaceae were present in high numbers. Significant differences in counts of Brochothrix thermosphacta were only obtained with initial presence of oxygen. The storage temperature had greater impact on microbial growth and off‐odour than the initial presence of oxygen in the packages. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of Different Packaging Methods on Quality and Shelf Life of Fresh Reindeer Meat

The impact of different packaging methods [vacuum, modified atmosphere packaging (MAP) (60% CO₂ and 40% N₂) and MAP + CO₂ emitter] on the quality of fresh reindeer meat (M. semimembranosus) stored at 4°C for 21 days was investigated. Colour and odour of the meat, drip loss, pH, microbial content, antioxidant capacity and cooking loss were measured. The MAP + CO₂ emitter resulted in prolonged microbial shelf life compared with vacuum and MAP without CO₂ emitter as lower level of total viable counts was detected after 13 and 17 days. Samples stored with CO₂ emitter also had lower drip loss. Samples stored in vacuum had significant lower L*‐value, higher a*‐value and lower intensity of freshness (odour and colour) compared with those stored in MAP and MAP with CO₂ emitter. However, MAP with a gas‐to‐product volume ratio of 1 : 1 seems to be too low in quality preserving. Increased partial pressure by adding a CO₂ emitter improved bacterial inhibition compared with vacuum and traditional MAP. Copyright © 2014 John Wiley & Sons, Ltd.     

Quality changes of treated fresh‐cut tropical fruits in rigid modified atmosphere packaging containers

There has been increasing demand for various fresh‐cut tropical fruits. However, their short shelf‐life has limited the market increase of this product. Quality changes (firmness, colour, total soluble solids (TSS), titratable acidity (TA), sensory quality and microbial safety) of fresh‐cut mangoes, pineapples, melons and mixes of these fruits were evaluated. Chemical treatments to reduce browning, firmness loss and decay of fresh‐cut tropical fruits were investigated. The most effective agents for fresh‐cut mangoes, pineapples and melons were 0.1m ascorbic acid, 0.2m ascorbic acid and 0.2m ascorbic acid + 0.2m calcium chloride, respectively. Fresh‐cut tropical fruits were packaged in various rigid containers (PET, OPS and OPLA). Gas composition in the package headspace and time to reach steady‐state condition varied among fresh‐cut packaging systems and affected their quality and shelf‐life. The effects of package permeability of O₂ and CO₂ on quality and shelf‐life of the fresh‐cut products are discussed. Extended shelf‐life was observed in fresh‐cut mangoes, pineapples and mixes packaged in PET due to reduced O₂ and elevated CO₂ atmosphere. A modified atmosphere of 6% O₂ and 14% CO₂ achieved in PET extended the shelf‐life of fresh‐cut pineapples from 6 to 13 days. Accumulation of CO₂ may impart an off‐odour of fresh‐cut fruits. The results suggested that the shelf‐life of fresh‐cut fruits could be extended by using proper rigid containers. Suitable mixes to create optimal equilibrium modified atmosphere had a potential to extend shelf‐life of short shelf‐life fresh‐cut tropical fruits. Copyright © 2006 John Wiley & Sons, Ltd.     

Combined effect of chill storage and modified atmosphere packaging on mussels (Mytilus galloprovincialis) preservation

Changes in biochemical indices, microbial growth, headspace and sensory quality of mussels which had been packaged in two modified atmospheres [Modified atmosphere packaging (MAP) 1: 60% CO₂/20% N₂/20% O₂ and MAP 2: 60% CO₂/40% N₂] and under vacuum (VP) were studied for 14 days. The results showed better quality retention and greater shelf life of mussels packaged under MAP 1 as compared to MAP 2 and VP samples. Increase in total volatile basic nitrogen followed the order: MAP 1 < MAP 2, VP < air (control) samples while increase in trimethylamine nitrogen followed the order: MAP 1 < air < MAP 2 < VP. The 2‐thiobarbituric acid (TBA) values of MAP 1 and air samples were significantly higher (p < 0.05) than the TBA values of VP and MAP 2 samples. MAP 1 showed a greater (p < 0.05) inhibition effect on total viable count of mussel samples than all other packaging conditions. Based primarily on odour scores, the MAP 1 samples remained acceptable up to ca. 10–11 days, the MAP 2 and VP up to ca. 7–8 days while the air‐packaged samples up to ca. 5–6 days of storage. Copyright © 2007 John Wiley & Sons, Ltd.     

Modified Atmosphere Packaging of Guava Fruit

Fully matured fresh guava fruits (Lucknow‐49) were precooled at 10 °C for 1 h and pretreated with 500‐ppm benomyl for 5 min. The fruits were packed in 25‐µm and 50‐µm LDPE bags with active modified atmosphere packaging of 3% O₂ + 5% CO₂, 6% O₂ + 5% CO₂ and 9% O₂ + 5% CO₂ gas concentrations and stored at 5 ± 1 °C and 10 ± 1 °C temperatures as well as non‐packaged as control. The shelf life of guava could be increased up to 42 days by packaging in 50‐µm LDPE bags with a gas concentration of 9% O₂ + 5% CO₂ and stored at 10 °C without much change in physical, biochemical and sensory characteristics. Physico‐chemical changes viz., PLW, pulp to peel ratio, firmness, TSS, total sugar, ascorbic acid and titratable acidity were observed minimum for fruits packed in 50‐µm LDPE bags at 3% O₂ + 5% CO₂ gas concentration at 5 °C storage temperature, but sensory score decreased drastically after 21 days of storage. Chilling injury was observed for the fruits packed at 5 °C storage temperature after 21 days of storage, and it was severe in 25‐µm LDPE bag at later stage. Control fruits over‐ripened with the highest weight loss (12.47%) on 6 days of storage and discarded from the storage. Copyright © 2014 John Wiley & Sons, Ltd.     

Maintaining quality of fresh strawberries through various modified atmosphere packaging

The influence of various modified atmosphere packaging (MAP) (21/0.05, 4/8 and 60/20% O₂/% CO₂) on fresh strawberry qualities [pH, acidity, °Brix, colour ( L, a ) and texture profile analyses] was investigated and compared during storage. Among the gas combinations used, pH of fresh strawberry was 3.281 at 1 day, and increased to 3.561 for air [21/0.05% (O₂/CO₂)], 3.53 for low (4/8) and 3.538 high (60/20) at 12 days. At the end of the storage, °Brix had evolved from the initial 7.07 to 5.47, 5.65 and 5.62 for 21% O₂; 4% O₂ and 60% O₂, respectively. Storage in 60% O₂ or 4% O₂ delayed the decrease of °Brix, titratable acidity and increased pH compared with 21% O₂. At the end of the storage, the strawberry L values had slightly decreased. Initial values of the firmness were 1067 gf and reduced to 501 gf (21% O₂); 613 gf (4% O₂) and 575 gf (60% O₂) at 12 days storage. Higher O₂ resulted in better springiness and chewiness than those treated with 4% O₂ and 21% CO₂, but did not significantly affect resilience. These results show that the use of various MAP gas compositions, including high oxygen, could be a good alternative to maintain fresh strawberry qualities for at least 12 days. Copyright © 2008 John Wiley & Sons, Ltd.     

Effects of PP‐based Nanopackaging on the Overall Quality and Shelf Life of Ready‐to‐eat Salami

A total of 1% nanoclay containing polypropylene (PP)‐nanocomposite and 1% nanoclay plus 5% poly‐beta‐pinene (PβP) containing PP‐active‐nanocomposite materials were produced and tested for packaging of sliced salami. The sliced salami was packaged using both nanofilms and multilayer film of PP/PA/EVOH/PE under vacuum, modified atmosphere packaging under 50% CO₂ and 50% N₂ and air and stored at 4 °C for 90 days. During storage, headspace gas composition; microbial, physical and chemical analyses; and sensory evaluation were performed. The antimicrobial effect of PβP containing nanomaterial was pronounced under vacuum, and no bacterial growth was observed for 75 days. An a* value decreased notably in all applications during storage and preserved best by the multilayered material under vacuum and high CO₂. Thiobarbituric acid reactive substances (TBARS) were 0.63 mg MDA/kg after the processing and gradually increased at all applications during increased storage. TBARS values of all vacuum applications were lower than that of modified atmosphere packaging applications. Rancid taste development was determined by sensory panelists when TBARS values were higher than 0.80 mg MDA/kg on the 90th day. There was no significant moisture loss, and no increase in hardness was determined during the whole storage time. The longest shelf life was 75 days for the sliced salami under vacuum and high CO₂ using the multilayer material. PβP containing nanomaterial provided 50 days of shelf life under vacuum, which is commercially considerable. Copyright © 2017 John Wiley & Sons, Ltd.     

Modified atmosphere packaging affects lipid oxidation,myofibrillar fragmentation index and eating quality of beef

The objective of this study was to evaluate the effects of different modified atmosphere packaging (MAP) systems applied during ageing and retail display on the quality of beef longissimus dorsi. The quality of the steaks was measured by sensory analysis, thiobarbituric acid‐reactive substances (TBARS), myofibrillar fragmentation index (MFI), protein oxidation, weight loss, cooking loss and vitamin E content. The study included 11 different packaging systems investigated in two separate trials, using O₂, CO₂, N₂ gas and vacuum in combination or alone during ageing and retail display. In some systems, loins were sliced into steaks before packaging, and in other systems, loins were vacuum packed and aged for 14–18 days, and thereafter were sliced and repacked in different atmospheres. Systems including high O₂ MAP resulted in a large increase in warmed‐over flavour and in TBARS as well as a decrease in juiciness, tenderness and vitamin E content, compared to anaerobic systems. Also, MFI was lower in high O₂ MAP steaks, and an increase in protein oxidation was seen, suggesting that the decrease in meat tenderness was due to reduced proteolysis and/or protein oxidation. In addition, the cooked steaks of high O₂ MAP looked well done, although the internal temperature was only 62°C, indicating premature browning. Ageing of steaks in N₂ did not affect any measured parameter compared to vacuum thermoforming packed muscle. Steaks stored in vacuum skin pack for 20 days were less tender than steaks stored in 100% N₂ for 18 days followed by 2 days in atmospheric air. In conclusion, packaging in high O₂ concentrations compromises several aspects of meat quality. Copyright © 2008 John Wiley & Sons, Ltd.     

Preservation of cold‐stored guavas influenced by package materials

The objective of this study was to evaluate the influence of package materials on the preservation of cold‐stored ‘Kumagai’ guavas. The treatments were: PO2, co‐extruded polyolephinic film with gas injection (5% O₂/5% CO₂/N₂); PO3, co‐extruded polyolephinic film with gas injection (5% O₂/5% CO₂/N₂); LDPE, linear low density polyethylene film; LDPE‐gas, linear low density polyethylene film with gas injection (3% O₂/8% CO₂/N₂); PVC, polyvinylchloride stretch film; PO1, co‐extruded polyolephinic film and control: non‐packaged guavas. Guavas were stored at 10 ± 1°C/80–90% RH for 21 days, and then transferred to room temperature. Gas composition within the package headspace was analysed during storage and the physical and chemical characteristics of the guavas were evaluated daily during ripening. The modified atmosphere provided by PO1 film was insufficient to promote the benefit of senescence control. Although PVC provided an atmosphere close to that recommended, it did not preserve the colour and pulp firmness. PO2, PO3, LDPE and LDPE‐gas retarded the senescence process of the guavas during 21 days at 10°C plus 2 days at room temperature, but harmed the normal ripening of guavas in some aspects. This can be explained by reduced O₂ and elevated CO₂ levels within these four packages. None of the packages influenced the titratable acidity and the soluble solids, but they did harm ascorbic acid synthesis. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of Pretreatment and Modified Atmosphere Packaging on Quality of dry Coleslaw mix

The aim of the study was to determine the effect of soaking in chlorinated water (100 ppm chlorine) or mild thermal treatment in water (55°C; 3 min) and modified atmosphere packaging on the quality and shelf life of dry coleslaw stored for 12 days at 4°C. Samples were packaged in low‐barrier film in modified atmosphere containing: 5/10/85, 20/25/55, 50/30/20, 70/30/0 %O₂/% CO₂/% N₂, and air atmosphere. In‐pack gas levels, sensory quality, microbial counts and cell permeability were determined. In comparison to non‐processed coleslaw, pretreatment of coleslaw, both consisting in soaking in chlorine solution and a mild thermal processing, resulted in a reduction by approx. 1 logarithmic cycle for counts of psychrophilic and lactic acid bacteria as well as mesophilic and psychrophilic yeasts, by 1 and 1.7 logarithmic cycle for coliform bacteria and by 2 up to 3 logarithmic cycles for Pseudomonas bacteria. Modified atmosphere (irrespective of its composition) used in product packaging was found to have no effect on the count of mesophilic bacteria. An elevated content of carbon dioxide in modified atmosphere (10, 25 or 30%) inhibited growth of psychrophilic bacteria and Pseudomonas bacteria up to 6 days of storage. In the case of coliform bacteria growth inhibition during storage was recorded both in the samples packaged in air atmosphere and in the atmosphere of 50/30/20 and 70/30/0 %O₂/% CO₂/% N₂. In samples packaged in the atmosphere of 70% O₂ and 30% CO₂ after 12 days the greatest cell permeability was recorded, which was connected with a deterioration of their microbiological quality. Copyright © 2015 John Wiley & Sons, Ltd.     

Production and Application of Active Packaging Film with Ethylene Adsorber to Increase the Shelf Life of Broccoli (Brassica oleracea L. var. Italica)

Broccoli (Brassica oleracea L. var. Italica) florets were packaged in low‐density polyethylene (LDPE) bags with or without ethylene adsorber under passive modified atmosphere and then stored at 4°C for 20 days. LDPE films with (8% Tazetut® masterbatch, M2) or without ethylene adsorber (M1) were tested. The effects of modified atmosphere packaging treatments on gas concentrations (O₂, CO₂ and ethylene) in the headspace, the mass loss, colour, texture, pH, total soluble solids, chlorophyll content, total phenolic content and sensory quality of packaged broccoli were determined by comparing with unpackaged (control) florets. Results revealed that deterioration occurred quickly in control broccoli, manifested mainly by mass loss, chlorophyll degradation and stem hardening. Also, it was found unacceptable by sensory panel after 5 days. Conversely, in those florets packaged under modified atmosphere packaging, especially for LDPE with ethylene adsorber (M2), all changes related with loss of quality were significantly reduced and delayed with time. Additionally, total soluble solids and total phenolic content remained almost unchanged during the whole period. Ethylene concentration was determined as 61.8 ppm in M1 and 0.33 ppm in M2, respectively, at the end of the storage. Thus, broccoli packaged with M2 films had prolonged storability up to 20 days with high quality attributes, this period being only 5 days in unpackaged control broccoli. Oxygen concentration decreased below 1% after 5 days of storage in M1, and the shelf life of broccoli in these bags was limited to 5 days because of risk for anaerobic fermentation. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of packaging film on the quality of ‘Chaoyang’ honey peach fruit in modified atmosphere packages

The quality of honey peach fruit stored at 2°C in modified atmosphere packages was studied. Three different thickness low‐density polyethylene (LDPE) films were used as packaging films. Honey peach fruits of ‘chaoyang’ were packaged in LDPE bags 15, 25 and 40µm thick and control (air). The respiration rate, O₂ and CO₂ concentrations in the packages, flesh colour, total soluble solid (TSS), titratable acidity (TA), flesh firmness (FF) and membrane integrity of the fruits were monitored. Compared to the control, MAP treatments inhibited the climacteric peak, avoided the increase of flesh colour, decreased the development of softness and retarded the reduction of TTS, TA and membrane integrity. Significant differences in the quality of the fruits were found between the three packages and the control (p ≤ 0.05). After 20 days at 2°C within the LDPE25 bags, a steady‐state atmosphere of 5% CO₂ + 4% O₂ was reached. Honey peaches stored in these bags showed the best quality at the end of the storage. Copyright copy; 2006 John Wiley & Sons, Ltd.     

Effect of Storage in a Low Oxygen Gas Atmosphere on Colour and Sensory Properties of Pork Loins

The objective of this study was to examine the quality characteristics of packaging materials and packaging units, and the viability and acceptability of the colour and sensorial properties of fresh pork meat during storage in low oxygen and high carbon dioxide modified atmosphere packaging up to 16 days at two temperatures (0°C and 4°C), as well as the sensorial properties of cooked meat. Packaging materials had good mechanical and barrier properties and were suitable for packaging in selected atmosphere. The concentration of oxygen during the whole storage period was less than 0.5% at both temperatures. The proportion of red colour (a*) was successfully maintained although the colour was slightly darker (L*) and the sensory value was lower when evaluated at the end of the storage period. Based on the obtained results and discussion, it can be concluded that samples packaged in a modified atmosphere with 40% CO₂ and 60% N₂ can be stored at 0°C for 15 days and at 4°C for 10 days. Samples had a good sensory quality until the 16th day, with the best results achieved on the 7th day. Copyright © 2013 John Wiley & Sons, Ltd.     

Comparison of Various Packaging Films for Mango Export

This study compared the effects of the use of various types of packaging films in maintaining quality, preserving bioactive compounds and extending shelf life of the ‘Nam Dok Mai’ mango. The principal techniques for maintaining the quality of mangoes are based on modified atmosphere packaging using highly gas‐permeable films and an ethylene‐removing mechanism. The films studied were non‐perforated highly gas‐permeable film, non‐perforated ethylene‐absorbing highly gas‐permeable film (HNPE), micro‐perforated highly gas‐permeable films (HMP) and common non‐perforated polyethylene film (LNP). These films were compared with non‐packaging treatment, which served as a control (C). Gas composition (O₂, CO₂ and C₂H₄) in the package headspace was monitored during storage at 12°C. The quality of mangoes were assessed by weight loss, colour (L* a* b*), texture, total soluble solids, titratable acidity, total phenolics, total flavonoids, ethanol concentration and sensory quality. Equilibrium‐modified atmospheres of 5 kPaO₂ + 5 kPaCO₂ and 4 kPaO₂ + 5 kPaCO₂ were achieved in the non‐perforated highly gas‐permeable film and HNPE packs, respectively. Carbon dioxide accumulation was observed in the HMP and LNP packs where CO₂ reached 17 and 10 kPa, respectively, after storage for 10 days. The shelf life of mangoes was extended to 40 days with HNPE, 35 days with HNP, and 30 days with HMP, as compared with 20 days with control and 5 days with LNP. HNPE, the film incorporated with fine particles of mordenite framework inverted‐type zeolite with ethylene‐absorbing ability, could further extend the shelf life of mangoes in addition to modified atmosphere packaging alone. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of modified atmosphere packaging with various sizes of silicon gum film window on the storage of Agrocybe Chaxingu Huang and the modelling of its respiration rate

An Agrocybe chaxingu Huang packaged in 5% O₂‐ and 10% CO₂‐modified atmospheres with different sizes (0, 0.5, 1.0 and 1.5cm²) of silicon gum film window was stored at a temperature of 3 ± 1°C for 20 days. Changes of ascorbic acid content, titratable acidity, electrolyte leakage and sensory characteristic were evaluated. Significant differences were found among the packages with different sizes of silicon gum film window on ascorbic acid content, titratable acidity, electrolyte leakage, general appearance, firmness and odour after 8, 8, 12, 12, 12 and 4 days of storage, respectively. The package with a 1.0cm² silicon gum film window was the most effective for keeping the quality of Agrocybe chaxingu Huang. Based on the optimum storage condition in this study, an enzyme kinetics respiration model was set successfully and the applicability of the enzyme kinetics respiration model was verified by using the packages of Agrocybe chaxingu Huang with weights of 105 and 125g, respectively. Copyright © 2007 John Wiley & Sons, Ltd.     

Effect of Initial Gas Flushing or Vacuum Packaging on the Ripening Dynamics and Preference for Kimchi,a Korean Fermented Vegetable

The effects of vacuum or modified atmosphere packaging conditions on the ripening dynamics of kimchi and sensory preference were investigated to determine the potential of initial atmospheric flushing as a method for improving quality at consumption. In all the packaging treatments (control of air, vacuumizing, CO₂ flushing and N₂ flushing), the partial pressures of O₂ and N₂ remained at nearly constant initial levels; therefore, the increases of package pressures were dominantly caused by the increases in the CO₂ partial pressures as a result of kimchi fermentation. The CO₂ production from kimchi was greater in the vacuumed and CO₂‐flushed packages. The initial vacuumed treatment helped to maintain relatively lower pressure during extended storage, and the pressure of the CO₂‐flushed package could have been reduced as a result of the high solubility of CO₂ in the aqueous product. Initial CO₂ flushing also provided the packaged product with a pleasant cool flavour at the properly ripened state.