气调包装(MAP)对草莓保鲜的影响

研究了气调包装技术对草莓贮藏保鲜的效果。结果表明,草莓最佳气调贮藏的条件为2.5%O2 16%CO2,它能够把草莓的货架寿命延长4～6d;利用LDPE和PVC复合膜明显优于LDPE膜和PVC膜。气调贮藏效果表明,MAP能明显抑制草莓的呼吸作用和水分的蒸腾作用,抑制糖、酸和花色苷等物质的降解。最后研究了包装内气体组分的动态变化。     

Mass transport analysis in perforation-mediated modified atmosphere packaging of strawberries

A space-and-time dependent mathematical model was developed to predict O₂, CO₂, N₂ and H₂O concentration in perforation-mediated polymeric packages during cold-storage of strawberries. The numerical solution of the corresponding mathematical model was obtained by applying the finite element method (FEM). The problem was solved in a domain corresponding to the headspace of a package augmented by the total void spaces of the contained bulk produce and for realistic boundary conditions. Transport of O₂, CO₂, N₂ and H₂O was modelled based on Maxwell–Stefan equations for gas transport through packaging’s headspace and on Fick’s law for diffusion through the micro-perforated packaging. The model predictions were tested against published experimental data of O₂ and CO₂ concentrations in modified atmosphere packaging storage of strawberries and the agreement is satisfactory. As for reaching the recommended in the literature gases concentrations for strawberry storage, the model predictions revealed that the tested micro-perforated polypropylene packaging combined with the adopted storage conditions are marginally adequate. To this end, the theoretical findings are suggestive of improvements, in terms of material properties, especially with regard to the permeability of the polymeric packaging film.     

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.     

Effect of integrated application of chitosan coating and modified atmosphere packaging on overall quality retention in litchi cultivars

BACKGROUND: The storage life of litchi is limited due to pericarp browning and decay. Modified atmosphere packaging (MAP) showed promising results for ensuring quality retention. However, to improve the efficiency of MAP the integrated treatment of a chitosan coating and MAP was investigated. RESULTS: The effect of chitosan (1.0 g L⁻¹) + MAP was compared with MAP (control), and was effective in preventing decay, browning and retaining the pericarp colour in the cultivar McLean's Red. Chitosan (1.0 g L⁻¹) + MAP significantly reduced polyphenol oxidase (PPO) and peroxidase (POD) activity, retained membrane integrity, anthocyanin content and prevented the decline of pericarp colour values during storage. The POD activity was greater than the PPO activity in the cultivars McLean's Red and Mauritius. The two cultivars differed in anthocyanin content and the activity of oxidation enzymes. The gas compositions within the packages were compared between chitosan at 1.0 g L⁻¹ and 20.0 g L⁻¹ concentration for both cultivars. Chitosan (20.0 g L⁻¹) + MAP lowered the respiration during storage in both cultivars compared to 1.0 g L⁻¹ + MAP. CONCLUSION: The McLean's Red cultivar is better suited for chitosan (1.0 g L⁻¹) + MAP integrated treatment than is Mauritius in retaining overall quality. Copyright © 2009 Society of Chemical Industry     

Optimization of an active package for wild strawberries based on the release of 2-nonanone

Active packaging is becoming in an emerging food technology to improve quality and safety of food products, commonly based on the retention or release of compounds which are beneficial for the product. In this work, an active packaging system based on the release of 2-nonanone has been optimized to increase the postharvest shelf life of fresh wild strawberries during the marketing stage. To avoid that excessive levels of this volatile could affect the berries' taste and cause consumer rejection of the product, a preliminary sensory analysis was carried out to determine the threshold value of 2-nonanone, 7.16 mg/kg fresh wild strawberries. Taking this threshold value into account, diverse quantities of 2-nonanone were tested to optimize the packaging parameters. Wild strawberry fruits were packaged in the active packages developed and their quality monitored during storage at 10 °C with exposure to light to simulate real-life conditions on supermarket shelves. The analyses of weight loss, SSC, gas composition and aroma volatiles provide evidences that exposure to the highest-tested 2-nonanone concentrations are an effective way of maintaining the quality of wild strawberries during distribution and sale without modifying their typical taste.     

Metabolic response to combined mild heat pre-treatments and modified atmosphere packaging on fresh-cut peach

The combined influence of mild heat pre-treatments (MHPT) and two types of modified atmosphere packaging conditions on metabolic response of fresh-cut peach was monitored during a 8-day long storage under refrigeration (4^C). The quality-affecting parameters were evaluated by physical and chemical methods (solute leakage, weight loss, firmness, colour, pH and soluble solid content) and by the evaluation of physiological aspects (respiration rate, PPO and PME activity) as well as vitamins, organic acids and sugars. Regarding main acid compounds, lower levels of malic acid are evident in heat-treated samples. Succinic and citric acids did not seem to be affected by the treatments. Provitamin A (β-carotene) was not affected by MHPT. The decrease in ascorbic acid content observed along the storage period was similar for both treated and untreated samples. Significant firmness improvements were obvious after MHPT due to the activation of PME (≈25%) and the ensuing production of calcium pectates. Efficiency of the passive modified atmosphere was enough to preserve the quality attributes of fresh-cut peaches subjected to MHPT.     

Volatile organic compound permeation through porous polymeric films for modified atmosphere packaging of foods

The use of perforated packaging films is increasing with the application of modified atmosphere packaging (MAP) to fresh produce. These films provide high to very high mass exchange rates which usefully allow oxygen ingress and carbon dioxide exit. However, the use of porous films also increases the loss of other food volatile components through similar processes. In this paper we present data on the permeation through porous films of several organic compounds found in many fruits and vegetables. The results are compared with those predicted by theoretical equations describing pore permeation processes. A discussion on the significance of these very high permeation values for product quality is also presented through the analysis of ethanol concentration evolution during MAP of mandarin segments. It was found that the barrier effectiveness of the fruit cuticle and the elevated partition coefficient of the organic compounds between the fruit (flesh) and the headspace appear to be responsible for the reduced food aroma compound loss. Copyright © 2004 Society of Chemical Industry     

酱鸭的气调包装保鲜技术研究

通过试验确定了酱鸭的气调包装保鲜工艺：50％CO2／50％N2的气调保鲜包装方法,调节酱鸭的盐度,实现了酱鸭常温保鲜2d。     

Effect of modified atmosphere packaging on visual quality and glucosinolates of broccoli florets

Broccoli (Brassica oleracea var. italica) florets were packaged in polyethylene bags with no holes (M₀), two microholes (M₁), and four macroholes (M₂), and then stored at 4 or 20 °C. The effects of modified atmosphere packaging (MAP) treatments on visual quality and glucosinolate contents were determined by comparing with non-wrapped florets. The results showed that MAP treatments, especially with M₀ and M₁, extended the shelf life and reduced the postharvest deterioration of broccoli florets stored at 4 and 20 °C. All three MAP treatments reduced the decreasing concentration rates of individual, total aliphatic and indole glucosinolates in broccoli florets when compared to those in the control, with M₀ being the most significant, followed by M₁ and M₂ during 23 days of storage at 4 °C or 5 days of storage at 20 °C. Broccoli florets with M₀ treatment maintained the visual quality and glucosinolate contents for 13 days at 4 °C and 3 days at 20 °C.     

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     

Influence of the modified atmosphere packaging on shelf life and quality of Navalinda sweet cherry

The benefits of different wrap-films for Navalinda sweet cherry, packaged in small-format (consumer packages), were analysed. A storage and distribution process entailing eight days at 4 °C plus four days at 20 °C was simulated. The cherries were packed in punnets and film-wrapped with one macroperforated film and two microperforated films of 0.30 (MAP.30) and 0.55 (MAP.55) µmol cm/cm² atm day of CO₂ permeability at 0 °C. Packing in MAP at 0 °C did not alter the subsequent respiratory intensity of the fruits at 20 °C; however, the respiratory intensity at 20 °C did increase when the storage temperature was raised to 4 °C. The concentration of CO₂ (%) inside the packets at 20 °C was proportional to the permeability of the films: MAP.30 (21%) and MAP.55 (15%). The microperforated films preserved fruit acidity and firmness while slowing down the darkening of colour, loss of quality and decay. Shelf life was most effectively prolonged with MAP.30 film. However, in view of the levels of hypoxia reached at 20 °C, its use is recommended only in the distribution and marketing processes with failsafe cold chains. The recommendations of use of the films, for the different markets, are expressed in light of the obtained results.     

Gas exchange in modified atmosphere packaging. 2: Experimental results with strawberries

Strawberries were used to test a new model describing gas transport through micro-perforated polypropylene films and fruit respiration involved in modified atmosphere packaging. Some experiments were conducted with empty packs initially filled with either 100% N₂ or 100% O₂. Simulations agreed very well with experiments only if we replaced the cross-sectional area of the micro-perforations by areas of approximately half the actual areas in order to account for the resistance of air around the perforations. It is also possible to fit the model to gas concentration changes in packs filled with strawberries, although deviations have been due to the contamination of strawberries by fungi. the model was used to quantify the consequences of the variability of pack properties (number of micro-perforations per pack and cross-sectional area of these perforations) on equilibrium gas concentrations and to define minimum homogeneity requirements for modified atmosphere packaging.     

The effect of modified atmosphere packaging on the quality of Honeoye and Korona strawberries

Strawberries (cultivars Honeoye and Korona) were stored in perforated polypropylene bags at 5 °C for 10 days. Unpackaged strawberries were used as a reference. Several quality parameters were monitored during the storage period. The packaged strawberries retained their weight throughout the experiment as opposed to the unpackaged samples which lost 1.5% of their weight per day because of dehydration. The aroma profile of Honeoye strawberries was not affected by storage in modified atmospheres. In Korona fruits, on the other hand, there was a considerable increase in ethyl acetate levels, indicating unwanted metabolism caused by the altered gas composition. The production of potential off-odours was, however, not possible to distinguish in the sensory analyses of the strawberries. The results indicated that storage in a modified atmosphere (11–14% O₂ and 9–12% CO₂) can be used to maintain the quality of Honeoye and Korona strawberries for a longer time, than if kept in air in open containers.     

Responses of CA-stored Bramley's Seedling and Cox's Orange Pippin apples to modified atmosphere retail packaging

The responses of Bramleys and Coxs apples to modified atmosphere (MA) retail packaging were studied in samples of fruit removed from controlled-atmosphere (CA) storage at monthly intervals through the marketing season, packed in MA or perforated control packs and held under simulated marketing conditions at 15C. The degree of modification of the pack atmospheres and the effects of MA packaging on fruit ripening changes were influenced by the duration and conditions of storage prior to packing. In addition, differential effects of MA packaging on the extent of retardation of flesh softening and skin yellowing were found as the storage period was extended. During 2 or 4 weeks at 15C, however, MA packs made from low density polyethylene (LDPE, 30 p) were effective in retarding changes in firmness and skin colour of Bramleys, previously stored for < 22 weeks (October-March) in 8% C02+ 13% O2 or for < 30 weeks (October-May) in 6% C02+3% 02. Similarly, during a 2-week marketing period at 15C, LDPE or ethylenevinylacetate (EVA, 30 II.) MA packs were effective in retarding some ripening changes in Coxs previously stored for < 31 weeks (Oc- tober-May) in < 1% C02+1.25% 02. The practical benefits of MA retail packaging for the marketing of apples are also discussed.     

包装材料及气调贮藏对薄荷保鲜效果的影响

以品质优良的薄荷为试验原料,在不同包装材料、不同气调比例及不同容积比3种条件下进行正交试验,在低温(4℃)条件下贮藏12h,分析各组薄荷在贮藏期内感官品质变化,并对其他相关理化指标进行测定。结果表明:在4℃条件下,以HDPE为包装材料,采用O2CO2N2的体积比为6985,容积比为15g处理后薄荷的失重率和VC含量的流失受到明显抑制,并且具有较高的感官品质、叶绿素含量和POD酶活性,将货架期延长至14d。     

Effects of modified atmosphere packaging (MAP) on the microbiological quality and shelf life of ostrich meat

Effects of various concentrations of O₂/CO₂ in modified atmosphere packaging on the microbiological quality and shelf-life of ostrich meat was investigated. Nine–12 months old ostriches were used. The iliofibularis muscle was cut into small cubes that were divided into five groups and then separately packaged under various gas mixes: air and O₂:CO₂:N₂ ratios of 80:20:0, 60:20:20, 60:40:0, and 40:40:20, using 2 different headspace ratios (1:1 and 3:1). The packaged meats were kept at 4 °C for 10 days and were analysed microbiologically, physico-chemically and sensorially. As a result, the meat quality and shelf-life of ostrich meat under various gas compositions were improved; microbial growth was delayed due to high CO₂ usage and shelf-life was increased by 5–7 days. However, an undesired loss of red colour of the ostrich meat may affect consumer acceptance.     

Effects of modified atmosphere packaging with different sizes of silicon gum film windows on Salicornia bigelovii Torr. storage

BACKGROUND: Salicornia bigelovii Torr. is a promising seasonal plant using seawater production but perishable with short shelf‐life under ambient conditions. To develop a modified atmosphere packaging (MAP) for extension of S. bigelovii shelf‐life, a nonselective polyethylene/polyamide (PE/PA) bag combining different sizes (0.6, 1.0 and 1.4 cm²) of silicon gum film (SGF) windows was tested, and low‐density polyethylene (LDPE) and perforated (1.0 cm²) PE/PA bags were used as controls. RESULTS: During 36 days of storage at 2 °C, the equilibrium compositions of O₂/CO₂ in LDPE, SGF1 (0.6 cm²), SGF2 (1.0 cm²) and SGF3 (1.4 cm²) were 3.0–5.0/4.5–6.5 kPa, 0.5–1.5/8.5–19.0 kPa, 2.5–5.0/5.5–10.0 kPa, and 6.0–13.0/4.0–6.5 kPa, respectively. Passive MAP treatments improved the quality attributes of S. bigelovii during initial storage; however, the 0.6 cm² SGF package markedly accelerated deterioration over the latter storage. The 1.0 cm² SGF package was observed to provide the optimal condition for S. bigelovii storage. CONCLUSION: The results show that passive MAP with optimized sizes of SGF windows could be an effective technique for prolonging shelf‐life of S. bigelovii. Copyright © 2009 Society of Chemical Industry     

Shelf-life of Domiati cheese under modified atmosphere packaging

The present study describes the effects of modified atmosphere packaging (MAP) on shelf-life extension, chemical, microbiological, and sensory properties of Domiati cheese. Five different MAP were studied [10% CO₂/90% N₂ (G1), 15% CO₂/85% N₂ (G2), 25% CO₂/75% N₂ (G3), 100% CO₂ (G4), and 100% N₂ (G5)]. Control samples were packaged in air (CA) and under vacuum. In both groups of cheeses, chemical analysis was significantly affected by MAP during cold storage. Ripening indexes were significantly affected by MAP during cold storage. Microbiological data showed that G4, followed by G5, were the most effective groups inhibiting the growth of total aerobic mesophilic and psychrotrophic bacteria, and yeasts and molds until the end of storage. Sensory evaluation was significantly affected by MAP and storage period, at 45 d CA cheese samples were judged as unacceptable. The best sensory properties were obtained in G5, G4, and G3 treatments, and recorded a relatively higher sensory evaluation scores. The best shelf-life extension was obtained in G5, G4, and G3 treatments.     

Development of shelf-life kinetic model for modified atmosphere packaging of fresh sliced mushrooms

Mushrooms are highly perishable and their shelf-life depends on processing, package properties and environmental conditions during storage and distribution. The aims of this work were to evaluate the effect of temperature and number of film perforations on quality and develop shelf-life kinetic model for a modified atmosphere packaging (MAP) for sliced button mushrooms. Sliced mushrooms were packed in a tray, covered with cellophane film, and stored for 7 days at four levels of temperature (0, 5, 10, and 15 °C) and three levels of perforations at each temperature ranging the number of perforations from 1 (58 perforations per m²) to 6 (349 perforations per m²). Headspace gas composition and quality parameters (weight loss, pH, firmness and colour) were measured throughout the storage period. Increasing the storage temperature required an increase of the number of perforations in order to obtain the optimum MAP conditions. Temperature had a significant effect (p < 0.05) on quality of sliced mushrooms. Firmness was identified as a critical quality parameter; therefore, a kinetic model was developed to describe the influence of temperature on firmness and predict shelf-life of sliced mushrooms. Fresh sliced mushrooms had a shelf-life of 1, 2, 4, and 7.5 days at 15, 10, 5, and 0 °C, respectively, under optimum MAP conditions.