Extending the quality of fresh strawberries by equilibrium modified atmosphere packaging

The impact of equilibrium-modified atmosphere packaging (EMAP) technology on extension quality [pH, acidity, brix, color (L, a, Chroma, hue)] and texture profile analyses of fresh strawberries was studied and compared during storage. Cast polypropylene (CPP), linear low density polyethylene (LLDPE) and polyethylene-terephthalate (PET)/Ethylene vinyl alcohol (EVOH)/Polyetlene-low-acetyl fractions (LAF) were used as heat-sealed lid and polyvinyl chloride (PVC/PE) tray with the purpose of obtaining equilibrium atmospheres. Among the various films used, pH of fresh strawberry was 3.275 at initial days, and increased to 3.39- for LLDPE; 3.42 for CPP and 3.44 PET/EVOH-LAF at the end of 10 days’ storage. Acidity values were 0.609 mg ml⁻¹ and decreased to 0.56 mg ml⁻¹ for LLDPE; 0.47 mg ml⁻¹ for CPP and 0.49 mg ml⁻¹ for PET/EVOH-LAF at end of storage. The strawberry brix had evolved from the initial 7.125 and reduced to about from 5.6 to 6.07 at the end of the storage. At the end of the storage, the strawberry L values had not significantly changed from the initial from 29.10 (L) to 28.9–26.46. Initial values of the firmness were 1,089 gf and reduced with ranged from 769 gf to 527 gf at end of the 10-day storage period. All the parameters in texture profile analyses showed a decline, except adhesiveness and springiness and used potential indicators of fresh strawberries. The overall results expressed that strawberry quality can be maintained effectively at least for 10 days using various polymeric lid films. PET/EVOH-LAF and CPP were much more effective then LLDPE due to barrier properties during storage periods. Quality of strawberry packaged with suitable high-barrier lid films have been prolonged significantly.     

牛肉冰温气调保鲜技术的研究

研究了以不同组合比例的CO2、O2、N2的气调包装,结合冰温（-1．5±1℃）贮藏的牛肉保鲜技术。以空气包装为对照,以牛肉的色差值、菌落总数、失水率、挥发性盐基氮、PH值为衡量指标,综合评价冰温气调保鲜牛肉的效果。研究结果表明,最佳的气调包装组分为10％O2,70％CO2和20％N2,在此条件下可以保鲜达28天;保鲜牛肉的PH值为6．09,挥发性盐基氮值为14．634mg／100g,菌落总数为3．7×10^4efu／g,色泽紫红,无异味。     

复合气调小包装技术保鲜效果研究

对多种食品应用复合气调包装机分别进行气调和普通包装,每天测定其相应指标,并进行统计分析。结果表明与普通包装相比气调包装具有显著的保鲜效果。     

Quality changes of fresh-cut kohlrabi sticks under modified atmosphere packaging

ABSTRACT:  The aim of this study was to determine the effect of different gas compositions on quality attributes and shelf life of kohlrabi sticks stored in modified atmosphere up to 14 d at 0 °C. Two commercial films were tested: oriented polypropylene (OPP) and amide-polyethylene (amide-PE). As a control, a microperforated OPP film was used. In order to study the changes in metabolic activity by minimal processing, the respiration rate and ethylene production at 0 °C were monitored for both intact stems and sticks. Changes in color, chemical parameters, sugars and organic acid contents, and sensorial quality of kohlrabi sticks were evaluated. An initial ethylene production of sticks was 13-fold higher than that of intact stems; meanwhile CO₂ production was 2-fold higher. However after 4 d of storage, a similar respiration rate for stems and sticks was found. Also the ethylene production of sticks and stems was steady around 15 to 20 nL/kg^/h after 10 d. Kohlrabi sticks showed a little change in chemical parameters and very low weight losses during cold storage. Sticks under an equilibrium atmosphere of 7 kPa O₂ and 9 kPa CO₂ at 0 °C reached by amide-PE kept an acceptable sensorial quality for 14 d.     

Storage behaviour of minimally processed pumpkin (Cucurbita maxima) under modified atmosphere packaging conditions

 Minimally processed vegetables in fresh, ready-to-cook form are gaining the confidence of both the trader and the consumer. This has led to a need to develop technology for increasing shelf life while maintaining the microbial, nutritional and sensory quality of minimally processed vegetables. This investigation was carried out on pumpkin in minimally processed form, packed in different polymeric film bags of varying permeabilities, creating an active equilibrium modified atmosphere within the package for the extention of storage life. It was observed that minimally processed pumpkin, which has a high respiratory rate at room temperature (155.7 mg CO₂/kg/h) could be stored for a period of 25 days at 5±2  °C under modified atmosphere packaging conditions with a minimum physiological loss in weight of 0.06% and marginally low changes in biochemical constituents, such as vitamin C, total soluble solids, moisture, carotenoids and titrable acidity, enabling the retention of near-fresh quality. The microbial loads of mesophilic aerobes and coliforms, which were log 5.5 and log 4.3 were less than threshold level. There was no growth of yeasts and moulds or mesophilic spore formers at the end of the storage period. Received: 24 January 2000 / Revised version: 4 April 2000     

Extending storage life of fresh ginseng by modified atmosphere packaging

Fresh ginseng (Panax ginseng) was packaged with LDPE and PVC films. The respiration rates of fresh ginseng were determined in modified atmosphere packaging (MAP) at 0, 10 and 20 °C. The changes in chemical compositions were also measured before and after storage. The results showed that respiration rates of fresh ginseng were suppressed more effectively in MAP, especially in a poly(vinyl chloride) (PVC) package. The storage life of fresh ginseng was significantly extended with better appearance and firmness for 210 days. The decay rate was only 1.3% and 1.0% in both low density polyethylene (LDPE) and PVC film package after 210 days of storage at 0 °C, respectively. The results of saponin analysis indicated that the contents of total saponin were not changed much in all treatments. Reducing sugar was increased by 2.7 to 5.3 times, while pectin decreased by 1.1 to 1.4 times after 210 days of storage at the range of 0–20 °C. Total sugar content also increased during storage, especially in LDPE packages and high temperature. It was considered that MAP was very effective storage method for keeping quality better with minimal quality loss and lower decay rate at lower temperature. Copyright © 2005 Society of Chemical Industry     

Sprouting and quality control of fresh ginger rhizomes by modified atmosphere packaging with film perforation

The quality of ginger rhizomes packaged in low density polyethylene bags (modified atmosphere packaging — MAP) without perforations (P-0), with 2 perforations (P-2), and 12 perforations (P-12) have been investigated for 5 months at 12±1°C. Sprouting and rotting rates of ginger in P-2 and P-12 were lower than ginger in P-0. Weight loss was higher in P-12 than P-0 and P-2. Surface L* (lightness) and a* (redness) values in P-2 and P-12 were lower and higher, respectively, than those found for P-0. Sensory appearance and overall acceptability were rated significantly better in P-2 and P-12 than in P-0. Internal color, firmness, soluble solids, and pH of ginger in MAP were not affected by presence of perforations. Therefore, MAP with the appropriate number of perforations (in this work, 2 perforations) could be a useful method to control sprouting and maintain quality except for surface color of stored ginger rhizomes.     

High carbon-di-oxide modified atmospheric packaging on quality of ready-to-eat minimally processed fresh-cut iceberg lettuce

Fresh-cut lettuce is a very well-known salad for today''s routines because it obliges minimal preparation to minimize the loss of health beneficial vitamins, minerals, antioxidants and other phytochemicals. It is a prodigious challenge to serve its consumers fresh. Quality of freshly processed lettuce under high CO₂ modified atmosphere packaging (MAP) has been investigated as a realistic alternative technique for its preservation. Storage under high CO₂ atmospheric treatments exhibited a significant impact in microbial development, electrolyte leakage, volatile metabolites and sensory quality of fresh-cut iceberg lettuce. This storage condition (MAP 1: 5 kPa O₂ and 20 kPa CO₂ balanced by N₂ at 7 °C for 6 days) inhibited the growth of mesophilic bacteria and yeasts; delayed the enzymatic browning (cut-edges and intact surface) of fresh-cut iceberg lettuce and overall visual quality was also in acceptance limit. The development of off-odors was perceived in high CO₂ MAP as a consequence of volatiles (ethanol and acetaldehyde) accumulation which was persisted at an inexcusable level during 6 days of storage periods.     

气调包装对冷鲜羊肉保鲜效果的影响研究

研究了单组分气体及不同比例气体组分对鲜羊肉进行气调包装后,对贮藏期间影响品质因素的关键技术指标的影响。试验条件下最优气体配比为CO2比例为20%,O2比例为65%。在此配比条件下,既可以改善并维持冷鲜羊肉良好的鲜红色泽,也可以在贮藏期间保持鲜肉的pH值和TVB-N值在规定的范围内,对延长冷鲜羊肉的贮藏期和保持良好的品质起到了一定作用。     

Behavior of flavonols and carotenoids of minimally processed kale leaves during storage in passive modified atmosphere packaging

Minimally processed kale leaves were packed in passive modified atmosphere and stored at 3 conditions: 1 °C in the dark and 11 °C with or without light exposure. The products were evaluated during storage in terms of headspace gas composition, sensory attributes, flavonol, and carotenoid contents. The sensory quality decreased slightly during 17 d at 1 °C in the dark. At 11 °C, the vegetable shelf life was predicted to be 6 d in the dark and 3 d with light. Quercetin and kaempferol were stable during storage for 15 d at 1 °C in the absence of light. At 11 °C in the dark, quercetin was stable during 10 d, increasing slightly on the 8th day. Kaempferol decreased up to the 5th day but increased on the 8th day, decreasing again on the 10th day. After 5 d at 11 °C under light, the flavonol levels were significantly higher than those of the initial values. Neoxanthin and violaxanthin did not change significantly after 15 d at 1 °C in the dark. Lutein and β-carotene, however, decreased 7.1% and 11.3%, respectively. At 11 °C in the dark, neoxanthin, violaxanthin, lutein, and β-carotene decreased 16.1%, 13.2%, 24.1%, and 23.7% after 10 d, respectively. At 11 °C under light, neoxanthin and lutein had a slight increase while violaxanthin and β-carotene decreased 23.1% and 16.5% after 5 d. Practical Application: Passive modified atmosphere packaging together with refrigeration can extend the shelf life of minimally processed kale, retaining the health-promoting compounds, flavonols and carotenoids. Quercetin, kaempferol, neoxanthin, and violaxanthin are stable and lutein and β-carotene slightly reduced.     

Keeping quality and safety of minimally fresh processed melon

Fresh-cut Amarillo melon was stored under passive modified atmosphere packaging (MAP) for 14 days at 5 °C. Three commercial films were tested: microperforated polypropylene (MPP), bioriented PP (BPP), and oriented PP (OPP). As a control, a macroperforated PP film was used. The effect of a citric acid dip treatment (0.52 mM) on the quality of the melon pieces packaged in OPP film was also evaluated. A similar final gas composition (4 kPa O2 plus 12–13 kPa CO2) within packages was achieved by using the three tested films. This atmosphere was effective for maintaining sensorial quality and microbial safety and for avoiding weight loss and translucency. When citric acid dip was applied, a reduction of microbial counts, a low discoloration, an increase of lightness, and a general improvement of visual appearance were found. However, after 14 days of storage, neither MAP treatments nor citric acid dip were enough to avoid softening of at least 23%, although the highest value (32%) was found in control pieces. Taking into account safety, quality attributes and consumer acceptance, shelf life of fresh processed melon stored under the studied MAP conditions could be stabilised for 10 days.     

Combined effects of irradiation and modified atmosphere packaging on minimally processed Chinese cabbage (Brassica rapa L.)

Cut Chinese cabbage with air, CO₂ or CO₂/N₂ packaging was irradiated at doses up to 2 kGy and the microbiological and physicochemical qualities were investigated during a refrigerated storage for 3 weeks. Irradiation significantly reduced the microorganisms, and additionally, the modified atmosphere packaging (MAP) enhanced the reduction of the total aerobic and coliform bacteria during storage. Irradiation effectively inhibited the changes of the titratable acidity and pH, while a significant effect was not shown in the texture by irradiation. Antiradical and antioxidant activity, and the phenolic contents were slightly increased by irradiation at 0.5 kGy, while the phenolic contents were reduced by irradiation over 1 kGy. Our results suggest that irradiation at 1 kGy or above can be used to enhance the microbial safety of cut Chinese cabbage without a significant loss in the quality attributes.     

气调包装中氧气含量对冷鲜猪肉品质的影响

为研究气调包装中氧气含量对冷鲜猪肉贮藏期间品质的影响,采用高阻隔性包装材料及两种不同气体比例(80%O2+20%CO2和50%O2+20%CO2+30%N2)对冷鲜猪肉进行气调包装,以托盘包装为对照,对冷鲜猪肉贮藏期间的菌落总数、色差、保水性、剪切力及包装内气体组成等指标进行检测分析。结果表明:气调包装组能够维持贮藏过程中包装盒内气体成分基本恒定;与托盘包装相比,50%O2气调包装可延长冷鲜猪肉货架期6 d,80%O2气调包装冷鲜猪肉货架期更长;气调包装组冷鲜肉红度值a*、黄度值b*显著高于(P0.05)托盘包装组;气调包装冷鲜猪肉保水性比托盘包装差,而两气调包装组之间无显著差异(P0.05);贮藏过程中气调包装组剪切力值大于托盘包装组(P0.05),80%O2气调包装组剪切力值小于50%O2气调包装组(P0.05);结论:气调包装会对冷鲜猪肉保水性、嫩度等品质造成一些不良影响,但可显著延长其货架期,采用80%O2比50%O2保鲜效果更好。     

Organoleptic properties of minimally processed apple pieces stored under modified atmosphere

Abstract

Fresh apple pieces were treated with 1‐2.5% ascorbic acid and stored in various modified atmosphere conditions at 0°C for 4 weeks. The desired whitish green color of apple pieces was retained for 4 weeks, during storage and after exposure to ambient conditions for 1 hrs, by the treatment with 2.0% ascorbic acid and vacuum packaging in a 65 mm (linear low density polyethylene (LLDPE)/nylon/LLDPE) 5 layer co‐extruded bag at 50% vacuum level. During storage in a 50 mm linear low density polyethylene (LLDPE) the 2% ascorbic acid treated apple pieces retained the desirable color only for 2 weeks. The use of ethylene and/or carbondioxide absorbants did not remarkabaly increase the quality and storage life of apple pieces stored in both LDPE and vacuum packages. Sensory and microbiological properties of the ascorbic acid‐treated apple pieces were of acceptable quality throughout the storage period of 4 weeks.     

Browning,polyphenol oxidase activity and headspace gas composition during storage of minimally processed pears using modified atmosphere packaging

Modified atmosphere packaging was used to prevent browning of minimally processed Conference pears, thus extending their shelf‐life. Colour changes as well as PPO activity were strongly influenced by the package headspace gas composition, which was determined by the packaging conditions. The initial colour of minimally processed pears was preserved for several weeks under cold storage in plastic pouches of very low O₂ permeability and an initial atmosphere of 100% N₂. A fractional conversion kinetic model fitted the experimental browning data with high accuracy. Colour degradation (ΔE*) of minimally processed pears occurred exponentially (k_ΔE = 0.019–0.077 day^?1) owing to changes in lightness (k_L = 0.021–0.07 day^?1). In contrast, PPO exhibited a linear increase in activity which could be related to the availability of O₂ in the package headspace. © 2002 Society of Chemical Industry     

Preservation of fresh meat with active and modified atmosphere packaging conditions

The sensory, microbiological and physicochemical attributes of fresh meat stored at 5 and 15 degrees C were affected by the combined effect of volatile compounds of oregano essential oil and modified atmosphere packaging conditions (40% CO2/30% N2/30% O2, 100% CO2, 80% CO2/20% air, vacuum pack and air). It was found that the extension of shelf life of meat samples depended on the packaging conditions and augmented in the order: air < vacuum pack < 40% CO2/30% N2/30% O2 < 80% CO2/ 20% air < 100% CO2. Longer shelf life was observed in samples supplemented with the volatile compounds of oregano essential oil and stored under the same packaging conditions mentioned above. The extension of shelf life may be due to the synergistic effect of volatile compounds of oregano essential oil and the modified atmosphere packaging used on the microbiological and physicochemical characteristics of meat. Indeed, both these hurdles can prolong and delay microbial growth or suppress the final counts of the spoilage microorganisms in comparison with the 'control' samples. The effect of essential oil volatile compounds was even more pronounced on the physicochemical changes of meat samples caused by microbial association. Oregano essential oil delayed glucose and lactate consumption, both indicators of meat spoilage aerobically as well as under 40% CO2/30% N2/30% O2, and 100% CO2. Finally, changes in other metabolites such as formic acid were also observed.     

调理配料对生鲜猪肉高氧MAP产品品质的影响研究

新鲜猪肉为原料,研究以食盐、复合香辛料、料酒添加量作为正交实验因素的生鲜调理猪肉在气调包装下的品质指标的变化.结果表明:与鲜肉相比,生鲜调理猪肉红度值提高,剪切力值与水分含量有小幅度上升,在4℃储藏过程中,生鲜调理猪肉色泽逐渐变暗(表现为a值下降),剪切力值呈现上升趋势,但货架期(5d)内生鲜调理猪肉的色泽与嫩度仍在可接受范围内,食盐与复合香辛料以及料酒含量对剪切力值的影响有显著交互作用(P＜0.05).综合正交实验直观分析及以剪切力值为目标函数的回归优化,最终得出配方为食盐:2％,香辛料:1％,料酒:7％.     

调理配料对生鲜猪肉高氧MAP产品品质的影响研究

新鲜猪肉为原料,研究以食盐、复合香辛料、料酒添加量作为正交实验因素的生鲜调理猪肉在气调包装下的品质指标的变化。结果表明:与鲜肉相比,生鲜调理猪肉红度值提高,剪切力值与水分含量有小幅度上升,在4℃储藏过程中,生鲜调理猪肉色泽逐渐变暗(表现为a值下降),剪切力值呈现上升趋势,但货架期(5d)内生鲜调理猪肉的色泽与嫩度仍在可接受范围内,食盐与复合香辛料以及料酒含量对剪切力值的影响有显著交互作用(p<0.05)。综合正交实验直观分析及以剪切力值为目标函数的回归优化,最终得出配方为食盐:2%,香辛料:1%,料酒:7%。      

The effect of modified atmosphere packaging with carbon monoxide on the storage quality of master-packaged fresh pork

Modified atmosphere packaging with carbon dioxide is effective for prolonging shelf-life of fresh meat. Addition of carbon monoxide to the system provides the advantage of enhancing meat colour. The study objective was to determine the effect of CO₂-MAP + 0.4% CO, vs. 100% CO₂-MAP, on the bacteriology and colour of retail-ready fresh pork stored for 8 weeks in a master-package system. Total plate counts were not affected and listeria was present on meat from both treatments. Colour was enhanced with the inclusion of CO, while no effect on lipid oxidation was observed. Use of CO in MAP provides sufficient storage life and product colour quality to permit shipment of fresh pork to distant markets. However, given the stable fresh colour of CO-treated meat and the lack of inhibition of pathogen growth by CO, there is concern that CO-MAP under certain conditions may pose a food safety risk.