Effect of modified atmosphere packaging on the microbial development and visible shelf life of a mayonnaise-based vegetable salad

The effect of a modified atmosphere of 20% carbon dioxide, 80% nitrogen, on the microbial development and visual shelf life of a mayonnaise-based vegetable salad is reported. The modified atmosphere delayed the spoilage of the salad at all three chosen storage temperatures. The principal organisms causing spoilage of the salads were yeasts, those spoiling the modified atmosphere packs having a fermentative ability. Modified atmosphere packaging of the vegetable salad would allow the manufacturer to increase the shelf life of the product from 40 to 54 days at 4°C storage, 12 to 22 days at 10°C storage, and 5 to 12 days at 15°C storage.     

Modified atmosphere packaging of seafood

The shelf life of seafood under current icing and refrigerated storage conditions ranges from 2 to 14 d, depending on species, harvest location, and season. Elevated carbon dioxide levels in modified atmosphere packaging (MAP) has been shown to inhibit the normal spoilage flora of seafood and double or triple shelf life. The threat of botulism, due to the presence of nonproteolytic psychyrotrophic Clostridium botulinum types B, E, and F, has been reason for caution in expanding this technology. This article examines the safety of MAP seafood through analysis and comparison of raw materials, research methodologies, quality indices, treatment, and packaging options.     

蘑菇气调包装系统

将蘑菇置于密闭容器内，测得容器内O2，CO2浓度由于呼吸作用随时间的变化曲线，由此推导出呼吸耗氧率RO2与O2浓度的数学关系式，并以此模拟包装不同重量蘑菇时，为了维持气调包装内一定的O2浓度，所需包装材料的透氧率函数；或者选定了包装材料后，模拟蘑菇的包装量函数，计算结果可用于优化蘑菇气调包装参数。     

Modified atmosphere packaging of common mushroom

Until recently, the films used for packaging fresh fruits and vegetables were not permeable enough to balance the high respiration rate of mushrooms. Consequently, modified atmosphere packaging (MAP) in sealed pouches or punnets was not appropriate for this commodity. Four microporous films in oriented polypropylene (OPP) and one film currently used to overwrap mushroom punnets (stretchable PVC) were tested. Mushroom punnets placed into pouches were stored at 4 and 10°C for 8 days. the influence of the modified atmosphere on the marketing quality of pre-packed mushrooms was assessed by measuring the external and internal colour, development stage, firmness and microbial growth. A mathematical model was used to predict the gas composition within the pouches at steady state as a function of the film properties and the characteristics of the plant tissues. the equation calculated from the simplified model shows a linear relationship between the reciprocal of O₂ concentration at steady state, (1/x) at 10 and 4°C and the reciprocal of the film permeability, (1/PmO₂).     

Modified atmosphere packaging of shredded lettuce

A retail package system was used to study the atmosphere modification which developed within packages of shredded Iceberg lettuce, sealed in trays with a range of polymer films of different gas permeabilities (oxygen permeability of 3000 to 10,000 ml/m²/day/atm. at 25°C). Modified atmospheres were produced both naturally by respiration, and by application of gas flushing techniques.
The effects of these modified atmosphere conditions on visual and sensory quality of shredded lettuce was observed by monitoring colour change and development of off-odours. An equilibrated modified atmosphere containing 1–3% O₂ and 5–6% CO₂was established with 35 um low density polyethylene film after flushing with 5% O2, 5% CO₂ in N₂. This resulted in a shelf-life of approximately 14 days at 5°C, almost double that of the controls.     

Modified atmosphere packaging of broccoli florets

A retail packaging system was used to study the atmosphere modification which developed within sealed packages of prepared broccoli florets with a range of polymer films of different gas permeabilities (oxygen permeability 3000–32,500 ml/m²/day/atm). Three methods of sealing were investigated and modified atmospheres (MA) were produced both naturally by respiration and by application of gas flushing techniques. The effects of these MA conditions on sensory quality were observed by monitoring colour change and development of off-odours. A 2–3% O₂, 2–3% CO₂ equilibrium MA was established using LF film to package broccoli florets when stored at 5°C. This, the only consistently aerobic MA attained, did not markedly improve retention of quality of broccoli florets when compared with broccoli stored in air. When broccoli florets were packaged with films which resulted in very low O₂ atmospheres (1% or less) foul of-odours shortened broccoli storage life.     

Modified atmosphere packaging of fruits and vegetables

Modified atmospheres (MA), i.e., elevated concentrations of carbon dioxide and reduced levels of oxygen and ethylene, can be useful supplements to provide optimum temperature and relative humidity in maintaining the quality of fresh fruits and vegetables after harvest. MA benefits include reduced respiration, ethylene production, and sensitivity to ethylene; retarded softening and compositional changes; alleviation of certain physiological disorders; and reduced decay. Subjecting fresh produce to too low an oxygen concentration and/or to too high a carbon dioxide level can result in MA stress, which is manifested by accelerated deterioration. Packaging fresh produce in polymeric films can result in a commodity-generated MA. Atmosphere modification within such packages depends on film permeability, commodity respiration rate and gas diffusion characteristics, and initial free volume and atmospheric composition within the package. Temperature, relative humidity, and air movement around the package can influence the permeability of the film. Temperature also affects the metabolic activity of the commodity and consequently the rate of attaining the desired MA. All these factors must be considered in developing a mathematical model for selecting the most suitable film for each commodity.     

Modified atmosphere packaging of filleted rainbow trout

Shelf‐lives of filleted rainbow trout (Oncorhynchus mykiss) packaged in over‐wrap, vacuum and gas mixture conditions and stored at 1 ± 1 °C were compared by measurement of pH, total volatile bases (TVB), hypoxanthine content, lipid oxidation (TBARS value), superficial counts of aerobic psychrotrophic flora and sensory analysis (colour, odour and flavour). The gas mixtures evaluated were 10% O₂ + 50% CO₂ + 40% N₂, 10% O₂ + 50% CO₂ + 40% Ar, 20% O₂ + 50% CO₂ + 30% N₂, 20% O₂ + 50% CO₂ + 30% Ar, 30% O₂ + 50% CO₂ + 20% N₂ and 30% O₂ + 50% CO₂ + 20% Ar. Sensory quality deterioration was delayed and bacterial growth as well as increases in pH, TVB and hypoxanthine levels were reduced by modified atmosphere packaging (MAP). Lipid oxidation was higher in gas packages with 20 and 30% O₂ than in those with 10% O₂. Vacuum‐packed fillets presented the lowest TBARS values. In summary, MAP gave rise to a significant extension of shelf‐life when compared with vacuum and over‐wrap packaging. No significant differences were found between the packages containing either N₂ or Ar. The best evaluated atmosphere consisted of 10% O₂ + 50%CO₂ + 40% N₂/Ar. © 2002 Society of Chemical Industry     

Modified atmosphere packaging inhibits browning in fennel

The effects of modified atmosphere packaging (MAP) to inhibit browning of the butt end cut zone of fennel bulbs stored during 14 days at 0°C followed by complementary air storage during 3 days at 15°C were studied. Selected bulbs were placed in 35 μm oriented polypropylene bags or in plastic baskets heat-sealed with nonperforated or perforated (control) polypropylene film. Changes in respiratory rate, ethylene emission, colour of both external leaves and butt end cut, as well as chemical and sensory attributes and browning development were monitored. A low to moderate nonclimacteric respiratory behaviour at 0°C with a respiration rate of 8-9 mg CO₂ kg⁻¹ h⁻¹ and an ethylene emission of 0.2-0.5 μl C₂H₄ kg⁻¹ h⁻¹ were found. Development of fungal attacks, chilling injury, decay and browning of external leaves were not detected for any treatment. All the MAP inhibited browning development of the butt end cut when evaluated after cold storage. However only the atmosphere of 6-7 kPa O₂ and 10-12 kPa CO₂ delayed that process at the end of complementary shelf life.     

Modified atmosphere packaging technology: A review

Modified atmosphere packaging is becoming increasingly common. It has been claimed that the technique enables significant shelf-life extension but in so doing presents an increased public health risk. This paper reviews the literature relating to the scientific basis of these claims. It demonstrates that shelf-life, sensory quality and safety of packaged products may be optimised only by harmonising a complex relationship between product and process.     

Modified atmosphere packaging improved quality of kohlrabi stems

To improve the keeping quality of the kohlrabi stems and avoiding wilting of the leaves, modified atmosphere packaging (MAP) with oriented polypropylene and amide-polyethylene copolymer bags was applied. Avoiding wilting of the kohlrabi leaves is crucial because European consumers consider the freshness of kohlrabi leaves as a key quality parameter. Whole kohlrabies were stored within, above-mentioned sealed bags, for 14 days at 0 °C and 95% RH, followed by 3 days at 10 °C. In the MA packages gas compositions of about 5 kPa O₂ and 10-15 kPa CO₂ were generated. The respiratory activity, C₂H₄ production, firmness (of stems and leaves), sugars, organic acids contents, as well as chemical and sensory quality attributes were monitored. The respiratory rate of the kohlrabi stems in air at 0 °C was 10-11 mg CO₂/kg/h with a C₂H₄ production lower than 0.05 μl/kg/h (traces). However, when the temperature was increased at 10 °C the respiration rate raised 3.5 folds. Acidity, pH, soluble solids, sugars and organic acids content and firmness did not show significant changes at the end of both cold storage and retail sale periods. MAP was very effective improving keeping quality of the stems and retarding wilting of the leaves. During the retail sale period at 10 °C, the bags must to be perforated to avoid anaerobic conditions.     

Combined effects of modified atmosphere packaging and thymol for prolonging the shelf life of caprese salad

The aim of this study was to investigate the influence of packaging atmosphere and a thymol dipping solution on the shelf life of caprese salad. Caprese salad was prepared with sliced tomatoes and mozzarella cheese. The samples were pretreated by dipping in a 400-ppm thymol solution and then packaged under air or under a modified atmosphere (65% N2, 30% CO2, and 5% O2). Changes in natural microflora of mozzarella and tomato, the O2 and CO2 in the head space, pH, and sensory characteristics were monitored during storage. The combination of the thymol dip and the modified atmosphere decreased the coliform populations in caprese salad from 5.65 to 4.23 log CFU x g(-1) and extended the shelf life from 3.77 to 12 days. A decrease in the concentration of Pseudomonadaceae from 7.03 to 5.09 log CFU x g(-1) was observed, and the lag phase was prolonged to approximately 3 days. The combination of the modified atmosphere and thymol did not affect the growth kinetics of lactic acid bacteria and enterococci, thus preserving the function of mozzarella cheese in the salad.     

Modified atmosphere packaging to extend the shelf life of tomatoes

An experimental retail packaging system was used to compare the atmospheric com-position and relative humidity which developed within packs sealed with a range of plastic films with different permeability properties, and to study the effects of these conditions on the rate of ripening (as indicated by colour change) and sensory quality of tomatoes. In packs sealed with several polyvinylchloride (PVC) films or with K-resin (a butadiene-styrene copolymer), an atmosphere containing 3–9% CO₂+3−9% 0₂ developed within circa 3–4 days at 10 or 12.5°C. Ripening of part ripe fruit was retarded, but continued normally after the packs were perforated, with no obvious adverse effects on the smell, flavour or texture of the fruit. In packs sealed with less permeable films (e.g. cellulose acetate), the internal atmosphere equilibrated to 10–18% CO₂+ < 2% O₂, resulting in complete inhibition of ripening, a high incidence of rotting and tainting of the fruit. Very high (98% or above) relative humidity within sealed packs also encouraged fungal spoilage. The possible commercial applications and benefits of this type of modified atmosphere (MA) packaging are discussed.     

Modified atmosphere packaging and vacuum packaging for long period chilled storage of dry-cured Iberian ham

Dry-cured Iberian ham slices were stored under vacuum and under four different modified atmospheres (60/40 = 60%N₂ + 40%CO₂; 70/30 = 70%N₂ + 30%CO₂; 80/20 = 80%N₂ + 20%CO₂; argon = 70%argon + 30%CO₂) at 4 ± 1 °C during 120 days. Gas composition, moisture content, pH, colour, pigment content, and lipid stability were measured, as well as sensory and microbial analysis were carried out throughout storage. A loss of intensity of red colour (a^*-values) was observed during storage in ham slices (P < 0.05). Consistently, MbFe(II)NO content also decreased throughout storage (P > 0.05). Slices of ham packed in 40%CO₂ (60/40) and 30%CO₂ (70/30) showed lower a^*-values than the rest of the batches after 60 days (P < 0.05), though differences were not evident after 120 days (P > 0.05). TBARs values showed an upward trend during the storage of packaged slices (P < 0.05). Vacuum-packed slices showed the lowest TBARs values and those packed with 40%CO_2, the highest. Sensory attributes did not vary significantly (P > 0.05) throughout storage under refrigeration and packed either in vacuum or in modified atmospheres. No safety problems were detected in relation to the microbial quality in any case.     

Modified atmosphere packaging (MAP) and pathogen growth and survival

A series of short articles on topics of interest to the dairy industry. The subjects covered will include chemistry, consumer affairs, marketing, microbiology, nutrition and processing, and contributions of 1000–1500 words (including tables and figures) are invited from any member of the Society.     

Modified atmosphere packaging of fresh produce: Current status and future needs

Fresh produce is more susceptible to disease organisms because of increase in the respiration rate after harvesting. The respiration of fresh fruits and vegetables can be reduced by many preservation techniques. Modified atmosphere packaging (MAP) technology is largely used for minimally processed fruits and vegetables including fresh, “ready-to-use” vegetables. Extensive research has been done in this research area for many decades. Oxygen, CO₂, and N₂, are most often used in MAP. The recommended percentage of O₂ in a modified atmosphere for fruits and vegetables for both safety and quality falls between 1 and 5%. Although other gases such as nitrous and nitric oxides, sulphur dioxide, ethylene, chlorine, as well as ozone and propylene oxide have also been investigated, they have not been applied commercially due to safety, regulatory, and cost considerations. Successful control of both product respiration and ethylene production and perception by MAP can result in a fruit or vegetable product of high organoleptic quality; however, control of these processes is dependent on temperature control.     

臭氧协同气调包装对鲜切叶菜的保鲜作用研究

采用臭氧水处理鲜切大白菜,并进行气调包装贮藏,通过正交实验法分析相关生理指标与保鲜效果,主要研究了4℃贮藏期间菌落总数、失重率、细胞膜透性、多酚氧化酶活性、VC含量和感官品质的变化。实验结果显示:臭氧水处理结合气调包装能有效控制微生物数量,保护了细胞膜透性及降低了VC含量的损失,并对多酚氧化酶有抑制作用,感官品质优良,可使鲜切白菜在4℃条件下保藏至20d以上。极差分析表明:优化的工艺参数为1.44mg/L的臭氧水处理5min协同5%O2/20%CO2/75%N2的气调包装。     

气调包装对混合鲜切果蔬保鲜效果的影响

以包装盒中充入空气为对照组,设置3组不同浓度的气调包装气氛比例,对预处理后的杨桃、砀山梨、黄瓜、小麦草4种混合鲜切果蔬进行包装,于4℃贮藏,通过测定并分析其理化指标,判断混合鲜切果蔬品质。结果表明,5%O₂+5%CO₂+90%N₂处理的混合鲜切果蔬贮藏8d后的感官品质较高,失重率较低,色泽和硬度保持良好,可溶性固形物含量降低较缓,微生物滋长得到抑制。说明气调包装对杨桃、砀山梨、黄瓜、小麦草4种混合鲜切果蔬有良好的保鲜效果,其中5%O₂+5%CO₂+90%N₂气氛比例下的保鲜效果最好。     

Modified atmosphere packaging as a means to alleviate package expansion of Korean fermented red pepper paste

Summary Korean fermented red pepper paste was packaged under a modified atmosphere (MA) of 30% CO₂/70% N₂ and 100% CO₂. A plain air package was also prepared as a control for comparison. The MA conditions were applied with a high gas barrier film and subsequently with a gas permeable film. Throughout the storage period at 13 °C, package volume, headspace gas composition, microbial flora, surface colour, pH and acidity were measured. An MA of 100% CO₂ suppressed the growth of aerobic bacteria and yeasts, and reduced the CO₂ production from the paste without any adverse effect on product quality, and thus alleviated the volume expansion of flexible packages stored at 13 °C. However, the reduced volume expansion for the package of high‐barrier film was not sufficient in prolonged storage. An MA package of 100% CO₂ using plastic film of appropriate gas permeability could be stored at 13 °C for 150 days without volume expansion or any adverse quality changes, and was also tolerant to temperature abuse conditions at 25 °C.     

Modified atmosphere packaging confers additional chilling tolerance on ethylene-inhibited cantaloupe Charentais melon fruit

Cantaloupe Charentais melon fruits are subject to chilling injury when stored at low temperatures, around 2 °C. Ethylene-suppressed cantaloupe Charentais melon, expressing a 1-aminocyclopropane-1-carboxylic acid (ACC)-oxidase gene in antisense orientation, showed strong, but not total, resistance to chilling injury, allowing an extended storage at low temperatures. Modified atmosphere packaging (MAP) is known to alleviate chilling injury symptoms in a variety of chilling-sensitive horticultural commodities. In the present work, we have compared the effects of MAP in non-retractile plastic film and storage in air on ethylene production, respiratory activity, development of chilling injury symptoms, water loss, ion leakage and accumulation of ethanol and acetaldehyde in wild-type and ethylene-suppressed melons, during storage at 2 °C and after re-warming at 22 °C. MAP reduced chilling injury and extended the postharvest life of wild-type fruit and conferred additional chilling resistance on ethylene-suppressed melons. Reduction of ethylene production and water loss are necessary to prevent chilling injury symptoms in melon.