Estimating packaging atmosphere–temperature effects on the shelf life of cod fillets

The behaviour of the natural microflora (total bacterial count, psychrotrophic bacteria, total coliforms, and lactic acid bacteria) of fresh cod fillets packaged in air, under vacuum, in a modified atmosphere with low oxygen concentration (5%) and in a modified atmosphere with high oxygen concentration (80%) was monitored during storage at different isothermal conditions from 4 to 12 °C. The growth data of the total bacterial count and total coliforms were used to model kinetically the shelf life of the samples in order to check the effects of storage temperature and packaging atmosphere. The acceptability times were compared with the stability times to establish if the shelf lives predicted were correlated. At 4 °C, cod fillets packaged under vacuum and in a modified atmosphere with low oxygen concentration had a higher shelf life (6.00 and 5.42 days), calculated from the growth of the total bacterial count, than the samples packaged in other atmospheres (1.96 and 2.62). Kinetic modelling could be valuable for the prediction of microbial fish quality loss.     

Botulism challenge studies of a modified atmosphere package for fresh mussels: inoculated pack studies

A series of botulism challenge studies were performed to determine the possibility of production of botulinum toxin in mussels (Mytilus edulis) held under a commercial high-oxygen (60 to 65% O(2)), modified atmosphere packaging (MAP) condition. Spore mixtures of six strains of nonproteolytic Clostridium botulinum were introduced into mussel MAP packages receiving different packaging buffers with or without the addition of lactic acid bacteria. Dye studies and package flipping trials were conducted to ensure internalization of spores by packed mussels. Inoculated mussel packages were stored at normal (4°C) and abusive (12°C) temperatures for 21 and 13 days, respectively, which were beyond the packaged mussels' intended shelf life. Microbiological and chemical analyses were conducted at predetermined intervals (a total of five sampling times at each temperature), including total aerobic plate counts, C. botulinum counts, lactic acid bacterial counts, package headspace gas composition, pH of packaging buffer and mussel meat, and botulinum toxin assays of packaging buffer and mussel meat. Results revealed that C. botulinum inoculated in fresh mussels packed under MAP packaging did not produce toxin, even at an abusive storage temperature and when held beyond their shelf life. No evidence was found that packaging buffers or gas composition influenced the lack of botulinum toxin production in packed mussels.     

微冻及真空包装对原汁整壳贻贝贮存期品质的影响

为研究微冻及真空包装对原汁整壳贻贝贮存期品质的影响,将原汁整壳贻贝进行真空包装及普通包装,于4和-3℃下进行贮存,对样品的感官评分、汁液流失率、pH、电导率、挥发性盐基氮(total volatile basic nitrogen,TVB-N)、2-硫代巴比妥酸(2-thiobarbituric acid,TBA)、菌落总数等指标的变化规律进行分析。结果表明:原汁整壳贻贝在贮藏过程中,随着时间的延长,感官评分下降;pH先降低后升高;汁液流失率、TVB-N、TBA、电导率和菌落总数均随贮存时间的延长而增长。-3℃微冻的保鲜效果明显优于4℃冷藏(P<0.05),真空包装的保鲜效果明显优于普通包装(P<0.05),-3℃微冻结合真空包装保鲜效果最佳,能显著延缓原汁整壳贻贝感官性状的下降(P<0.05),抑制汁液流失率、电导率、TVB-N值、TBA值的上升(P<0.05),延缓pH最低点出现的时间(P<0.05),抑制菌落总数的增长(P<0.05)。综合比较分析,4℃普通包装、4℃真空包装、-3℃普通包装、-3℃真空包装的货架期分别为6、15、15和60 d。因此,微冻结合真空包装能较好维持原汁整壳贻贝的感官性状及品质稳定性,有效延长货架期。     

Color and thiobarbituric acid values of cooked top sirloin steaks packaged in modified atmospheres of 80% oxygen, or 0.4% carbon monoxide, or vacuum

Case-ready fresh beef is typically packaged in a modified-atmosphere with approximately 80% oxygen and 20% carbon dioxide. Recently, USDA approved distribution of fresh meats in a master bag system using 0.4% carbon monoxide (CO). This study compared effects of packaging system (vacuum, 80% oxygen, 0.4% carbon monoxide), fresh meat storage time (7-21 days) and cooking temperature (49-79 °C) on extent of myoglobin denaturation, color and rancidity in cooked top sirloin steaks. Steaks packaged in 80% oxygen or CO retained desirable red color for 14 and 21 days storage, respectively. Steaks stored in 80% oxygen exhibited the greatest TBA values and myoglobin denaturation at all storage times and cooking temperatures. Steaks stored in high oxygen developed brown interior color at internal temperatures as low as 57 °C, the premature browning effect. Premature browning and rancidity associated with steaks packaged in 80% oxygen was prevented by packaging in 0.4% CO or vacuum.     

不同包装方式对冷鲜鹿肉品质的影响

用出水率、菌落总数、挥发性盐基氮及pH值为指标,研究真空热缩包装、气调包装、真空贴体包装三种不同包装方式对冷鲜鹿肉在(0±2)℃条件下品质的影响。实验结果显示,在相同的冷藏条件下,真空热缩包装的鹿肉品质最佳,保鲜效果最好,产品的保质期最长达(70 d),气调产品色泽最好但包装保质期最短(7 d)。     

VACUUM PACKAGING OF FRESH BEEF: A REVIEW

Vacuum packaging is a method of distributing beef primal cuts in oxygen impermeable bags under vacuum. Increased technology in the application of vacuum packaging has verified that it provides a means of prolonging the shelf-life and palatability of beef during extended periods of shipment and storage. Additional advantages of vacuumized storage include reduction in weight loss from evaporation and trimming, preservation of color, increased hygienic control and enhanced palatability due to controlled aging. Such benefits have been achieved by intensified research efforts directed towards improving packaging systems. The objective of this review is to discuss these research efforts and identify those factors associated with the quality of vacuum packaged beef.     

Effects of dietary vitamin e supplementation and packaging on the quality of minced beef

Friesian cattle, aged 26-27 months, were fed a diet supplemented with 2000IU α-tocopheryl acetate/kg feed/day and another group was fed a basal diet (20IU/kg feed/day) for approximately 50 days prior to slaughter. Following frozen storage (-20°C for 8 weeks) semimembranosus muscles from basal and α-tocopheryl acetate supplemented cattle were minced and vacuum packaged, aerobically packaged or packaged under modified atmospheres (MAP) (30% O(2): 70% CO(2); 70% O(2): 30% CO(2); 80% O(2): 20% CO(2)). Samples were held under refrigerated (4°C) display (fluorescent lighting, 616 lux) for eight days. Vacuum-packaged samples were held under similar conditions but in complete darkness and allowed to bloom for a minimum of 4hr prior to taking colour readings. TBARS values and Hunter a values in minced beef were measured every two days. α-Tocopherol concentrations were significantly (p<0·05) higher in minced meat samples from the supplemented group than in the basal group. Significant (p<0·05) reductions in α-tocopherol concentrations in supplemented meat samples were observed with increased concentrations of oxygen in different packaging systems after eight days of refrigerated storage. TBARS values were reduced over the whole retail display period for all packaging systems when α-tocopheryl acetate supplemented beef was used. TBARS values increased as oxygen levels increased in MAP. Hunter a values showed that vitamin E supplementation in combination with vacuum packaging and MAP improved the colour stability of meat during the first 4 days of storage, however, the failure of MAP to extend meat colour for longer periods of time was probably the result of prior storage at -20°C for 8 weeks.     

Microbiological,chemical and sensory assessment of mussels (<Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis>) stored under modified atmosphere packaging

Wild mussels (Mytilus galloprovincialis), were packaged aerobically under vaccum packaging(VP) and modified atmosphere packaging (MAP (50%/50% CO₂/N₂: M1, 80%/20% CO₂/N₂: M2, 65%/35% CO₂/N₂: M3), and stored at 2 ± 1 °C. Quality evaluation was carried out using microbiological, chemical and sensory analyses. Microbiological results revealed that M2 and M3 delayed microbial growth compared to M1. Of the chemical indices determined, the TVB-N and TMA-N values of M2 remained lower than the proposed acceptability limits of 35 mg N/100 g and 8 mg N/100 g, respectively, up to 8 days of storage. All of the MAP and VP mussel samples exceeded these limits after 12 days of storage. All samples retained desirable sensory characteristics during the first 8 days of storage. Based on microbiological and chemical analyses along with sensory evaluation, M2 and M3 gave a longer shelf-life compared with VP and M1. M2 gas mixture was the most effective for mussel preservation.     

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.     

Microbiological and sensory changes in "Morcilla de Burgos" preserved in air, vacuum and modified atmosphere packaging

"Morcilla de Burgos" is the most popular blood sausage in Spain. Traditionally, this product is distributed and sold without packaging in the local market. To extend its shelf-life and expand the market, different packaging methods have been employed and compared: "morcilla" stored in air (without packaging), in vacuum and in modified atmosphere packaging (MAP) using three different CO(2) concentrations 30%, 50% and 80% and balanced with N(2). Total viable count (TVC), psychrotrophs, lactic acid bacteria (LAB), pseudomonads, enterobacteria, moulds and yeasts, enterococci, Staphylococcus aureus, and sulfite reducing clostridia were analysed during storage at 4°C. Sulfite-reducing clostridia, pathogenic staphylococci, and enterococci were not detected in any sample. In air-stored "morcilla" a significant increase in all microbial groups was observed during storage. Pseudomonads were the predominant microorganisms reaching a population higher than 8 log cfu/g after 27 days of storage. On the other hand, a decrease in pH was noticed in MAP and in vacuum packaged "morcilla" (pH 4.73) during storage. At the same time, LAB becomes the predominant species in all these packaged samples. The rest of the microbiota did not grow during storage. In "morcilla" packed with 50% and 80% of CO(2), counts of pseudomonads and enterobacteria were lower than found in the vacuum packs. Sensory analysis showed that shelf-life of "morcilla" stored in air did not exceed 17 days, while samples packed under vacuum and with 30% CO(2) were acceptable until 22 days of storage. "Morcillas" packaged with 50% and 80% CO(2) were sensorially acceptable for 32 days.     

Irradiated Ground Beef: Sensory And Quality Changes During Storage Under Various Packaging Conditions

Ground beef patties (irradiated with 2 kGy and nonirradiated) were packaged using oxygen permeable (polyolefin) or oxygen impermeable material (polyethylene). Samples were irradiated in air and stored in air; irradiated under vacuum and stored under vacuum; or irradiated under vacuum and stored in air. Changes in flavor, texture, juiciness or aftertaste were evaluated after either 1 or 7 days storage at 25°C prior to cooking. Irradiated "Vac/Air" samples were more tender, irradiated "Vac" samples were more moist, and irradiated "Air" samples had the least aftertaste. A 3 log₁₀ reduction in total aerobic counts was detected immediately after irradiation. No difference in lipid oxidation was found within the first week of storage, regardless of packaging atmosphere. Shelf life of ground beef patties was extended 55 days at 4°C.     

Identification and evaluation of volatile compounds of vacuum and modified atmosphere packaged beef strip loins

Beef strip loins were packaged and stored for up to 28 days at 3°C in high-oxygen barrier film under vacuum and in 100% CO(2), 40% CO(2)/60% N(2) and 20% CO(2)/80% O(2). As storage progressed, loins packaged and stored in 20% CO(2)/80% O(2) developed strong off-odors. 1-hexene, methyl thiirane, ethyl acetate, benzene and 1-heptene were detected in these packaged loins beginning at 7 to 14 days of storage. With the exception of 1-hexene, these compounds were not consistently detected in loins stored in vacuum, in 100% CO(2), or in 40% CO(2)/60% N(2), and these packaged loins developed much less off-odor during storage than loins packaged and stored in 20% CO(2)/80% O(2). A large number of volatile compounds from the headspace of the packaged loins originated from the packaging material. Lactobacillus plantarum became the dominant flora on loins stored under vacuum and under 40% CO(2)/60% N(2) while Leuconostoc mesenteroides subsp. mesenteroides predominated in loins stored in 100% CO(2). Pseudomonas putida eventually dominated on loins stored in 20% CO(2)/80% O(2).     

托盘和真空包装对冷却猪肉中MetMb还原活性的影响

在冷却肉的贮藏过程中,其肌红蛋白(Mb)被氧化为高铁肌红蛋白(MetMb),导致了冷却肉的褐变。研究了托盘包装和真空包装条件下,冷却肉自身的还原系统活性变化规律及其对肉色稳定性的影响。在2周的贮藏期内,真空与托盘包装冷却肉糜肌浆蛋白粗提液的还原活性持续下降;但真空包装组MetMb还原酶粗提液还原活力第1天到第14天活性差异不显著,托盘包装组前后差异显著。真空包装组在贮藏期间MetMb含量持续下降,但托盘包装组MetMb含量则持续上升,说明无氧条件有利于MetMb的还原。托盘包装组TBA在贮藏期间持续上生,但真空包装组TBA变化不明显。结果表明,托盘包装不利于冷却肉自身MetMb还原能力的维持,而真空包装的无氧环境,有利于MetMb的还原和肉色的保持。     

Modification of in-pack conditions to extend the storage life of vacuum packaged lamb

High pH (>5·9) lamb loins from a research abattoir were subjected to differing packaging treatments to determine whether package modification could reliably extend the storage life of chilled lamb cuts beyond that attained by cuts vacuum-packaged in film of low gas permeability, as in current commercial practice. Treatments applied were carbon dioxide flushing or addition of a citrate buffer (pH 4·8), a 5% lactic acid solution or a Lactobacillus inoculum (plastic packs only) and packaging in a plastic film of moderately low oxygen permeability (140 cc/m(2)/24 h at 25°C and 90% relative humidity) or in a foil laminate of immeasurably low oxygen permeability. After 12 weeks' storage at -0.5°C, the cuts packaged in the plastic film were spoiled by off-odours produced by enterobacteria, except for inoculated cuts, which, instead, had developed unacceptable dairy flavours. In contrast, cuts packaged in foil laminate developed floras of lactobacilli that had not caused spoilage after 12 weeks, and meat colour was much improved by the exclusion of oxygen. Loin cuts from a commercial packaging operation were packaged in a shrinkable plastic film of low oxygen permeability (30 to 40 cc/m(2)/24 h at 25°C and 90% relative humidity), in foil laminate, or in foil laminate after the addition of 5% lactic acid solution. For the first 6 weeks, cuts were stored in a commercial chiller nominally operating at 0°C; subsequently, they were held in a laboratory chiller at -0.5°C. Some cuts packaged in the shrinkable plastic were spoiled after 9 weeks' storage and all were spoiled at 12 weeks, because of off-flavours produced by enterobacteria. All cuts packaged in the foil laminate were very acceptable at 9 weeks but most were spoiled by off-flavours at 12 weeks. Most cuts treated with lactic acid and packaged in foil laminate were unspoiled after 12 weeks. The packaging requirements indicated to be necessary for reliable extension of the storage life of vacuum packaged lamb are discussed.     

Packaging optimisation for portioned Canestrato di Moliterno cheese

Different polymeric films and various headspace conditions (air, vacuum and four different modified atmosphere packaging) were combined to select a packaging system that assured the desired shelf life for two types of portioned Canestrato di Moliterno cheese ripened for 4 and 12 months. To evaluate the quality deterioration of the packaged cheese samples under refrigerated conditions, texture change, weight loss, water activity, moisture content, microbial contamination, pH and sensory attributes were monitored during storage. The results highlighted that a high‐barrier multilayer film delayed proliferation of moulds and gave the best results for both types of ripened cheese.     

PACKAGING PRESERVATION OF β-CAROTENE IN SWEET POTATO FLAKES USING FLEXIBLE FILM AND AN OXYGEN ABSORBER

Sweet potato flakes are potentially an affordable, shelf-stable source of provitamin A β-carotene. Because β-carotene is susceptible to oxidative degradation, particularly in dehydrated food materials exposed to atmospheric oxygen, several packaging conditions were evaluated for enhancement of β-carotene retention in sweet potato flakes during storage. The flakes were packaged in either a polypropylene film (high oxygen permeability) with air headspace or a nylon laminate film (low oxygen permeability) with air headspace, under vacuum, or with an Ageless oxygen absorber sachet enclosed. Packaged flakes were stored in the dark at ambient laboratory temperature (～23C), and β-carotene content was determined at intervals from 0 to 210 day storage using reversed-phase liquid chromatography. Among the packaging conditions tested, β-carotene retention was enhanced incrementally as the apparent availability of oxygen was reduced (nylon > polypropylene; oxygen absorber > vacuum > air headspace). The combined use of oxygen absorbers and flexible oxygen barrier film gave excellent retention of β-carotene during the 210 day trial.     

不同气调包装结合冰温贮藏对羊肉保鲜效果的影响

为延长鲜羊肉的保鲜时间,研究不同气体组分的气调包装对羊肉冰温贮藏过程中品质的影响。以真空包装为对照,比较75% O2＋25% CO2、75% N2＋25% CO2气调包装羊肉在－1 ℃冰温条件下贮藏过程中感官品质、色泽、汁液流失率、嫩度、挥发性盐基氮、pH值、微生物等品质指标的变化。结果表明：真空包装羊肉的汁液流失率显著高于2 种气调包装,而75% N2＋25% CO2气调包装羊肉的色泽和感官评分最差。75% O2＋25% CO2气调包装的保鲜效果最好,其色泽和感官评分最高,汁液流失率较小,pH值最低,－1 ℃冰温条件下贮藏42 d时,羊肉的菌落总数、假单胞菌菌数、乳酸菌菌数的对数值分别为5.91、5.95、5.23 （lg（CFU/g））,其中菌落总数指标符合国家二级鲜肉标准。因此,－1 ℃冰温条件下结合75% O2＋25% CO2气调包装可以使羊肉有效保鲜42 d,是较好的鲜羊肉保鲜方法。     

不同包装方式调理牛排在冰温贮藏过程中品质变化特点

本试验旨在为调理牛排的贮藏保鲜提供数据参考,以生鲜牛里脊为原料,经整形、腌制等工艺制成调理牛排,并对其进行托盘包装和真空包装,将包装后的成品贮藏于0~4 ℃及0~-1.5 ℃两种环境下,即托盘组冷藏条件(ST)、真空组冷藏条件(SZ)、托盘组冰温条件(BT)以及真空组冰温条件(BZ),并定期检测汁液流失率、感官评价、感官总评分、TBARS值、菌落总数、TVB-N值以及pH指标变化。结果表明:托盘包装下,BT组的货架期为20 d,与ST组的12 d相比能将货架期延长8 d;真空包装下,BZ组贮藏的货架期为32 d,与SZ组的20 d相比将货架期延长了12 d。在同种贮藏温度下,除汁液流失指标外,真空组各项指标变化幅度都低于托盘组,能够较好的维持调理牛排的品质;在贮藏期间,真空包装方式下,汁液流失较严重,且显著高于托盘组(p<0.05);BT组色泽变化较缓慢,BZ组气味变化较缓慢。相关性分析发现,SZ组、BZ组以BT组,汁液流失率、感官总评分、TBARS值、菌落、TVB-N值以及pH与调理牛排的贮藏时间显著相关。ST组,仅感官评分、菌落总数以及TVB-N与调理牛排品贮藏时间显著相关。因此,在贮藏过程中,冰温贮藏和真空包装方式均能有效改善调理牛排品质,且两者结合效果改善效果更明显。     

Effect of active and modified atmosphere packaging on quality retention of dark chocolate with hazelnuts

The present study investigated the effect of active and modified packaging as well as packaging material oxygen permeability on quality retention of dark chocolate with hazelnuts. Dark chocolate was packaged in: a) polyethylene terephthalate//low density polyethylene (PET//LDPE), and b) polyethylene terephthalate coated with SiOx//low density polyethylene (PET-SiOx//LDPE). Samples were packaged either under, vacuum or N₂ or with an oxygen absorber and stored in the dark at 20 °C for a period of 12 months. “Commercial” control samples for comparison purposes consisted of chocolate packaged in aluminum foil in air while “model” control samples used for sensory evaluation consisted of chocolate packaged in glass jars and stored at ? 18 °C. Quality parameters monitored were: peroxide value, hexanal content, color, fatty acid composition and volatile compounds. Of the sensory attributes color, texture, odor and taste were evaluated. PV ranged between 0.80 for fresh dark chocolate with hazelnuts and 6.51 meq O₂/kg chocolate fat for commercially packaged samples after 12 months of storage. Respective values for hexanal were 0.53 and 7.56 mg/kg. % Saturated fatty acids (SFA) increased with a parallel decrease in monounsaturated fatty acids (MFA) and polyunsaturated fatty acids (PUFA) after 12 months of storage mainly in least protected samples (commercial package). Likewise, after 12 months of storage an increase in concentration of aldehydes, ketones, alcohols and alkanes (p < 0.05) with a parallel decrease in pyrazines where observed especially in case of least protected products after 6 and 12 months of storage. In general after 12 months of storage chocolate showed whitening of the surface resulting to an increase in L* and a* values (p < 0.05) and a decrease in b* value. Dark chocolate with hazelnuts retained acceptable quality for ca. 8 months in commercial packages. For samples packaged in PET//LDPE irrespective of storage atmosphere the shelf life was 8 to 9 months and for samples packaged in PET-SiOx//LDPE irrespective of storage atmosphere the shelf life was 11 months. Finally for samples packaged with an oxygen absorber irrespective of packaging material the shelf life was at least 12 months.Industrial relevanceChocolate packaged with an oxygen absorber in a barrier packaging material will maintain its aroma, taste and nutritional quality substantially longer than other packaging methods.