不同气调比例对酱卤鸭腿货架期的影响

以酱卤鸭腿为原料,以菌落总数,感官评定,电子舌为评价指标,研究3种气调包装比例(45%O_2+45%CO_2+10%N_2;5%O_2+70%CO_2+25%N_2;30%CO_2+70%N_2)分别在25℃和4℃条件下贮藏对酱卤鸭腿货架期的影响。研究结果表明:在25℃条件下,3组气调包装都能存放2d。在4℃条件下,45%O_2+45%CO_2+10%N_2;5%O_2+70%CO_2+25%N_2;30%CO_2+70%N_2分别能放置10d,8d,8d。     

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%O_2+5%CO_2+90%N_2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%O_2+5%CO_2+90%N_2气氛比例下的保鲜效果最好。     

气调包装对空心菜净菜冷藏品质的影响

以空心菜为对象,研究采后经质量浓度1. 8 mg/L臭氧水清洗过的空心菜净菜通过不同的气调包装方式,在10℃条件下的冷藏保鲜效果。研究表明:空气包装、低氧(5%O_2、10%～15%CO_2、80%～85%N_2)气调包装,均不利于采后空心菜净菜保鲜,而适宜的高氧(10%O_2、5%～10%CO_2、80%～85%N_2)气调包装,特别是(10%O_~(2+)10%CO_~(2+)80%N_2)的气调包装工艺最适合空心菜净菜的采后贮藏,可以有效地保持空心菜感官品质,维持叶绿素、维生素C的含量,延缓水分迁移,抑制丙二醛积累,延缓组织氧化衰老,抑制细菌生长繁殖,延缓腐败,较对照组空气包装相比,货架期延长了2 d。     

包装方式对减轻冷却猪肉辐照异味的影响

冷却猪肉分别经真空包装、保鲜膜包装、复合包装、气调包装等预处理后辐照2.8kGy剂量,低温4℃冷藏,研究包装方式对减轻猪肉辐照异味的影响。结果表明,复合包装和60%O_2+30%CO_2+10%N_2组合的气调处理均可有效去除猪肉辐照异味,其中60%O_2+30%CO_2+10%N_2组合的气调处理4.2kGy剂量辐照后异味达到不可察觉的程度。     

正交与神经网络优化菠萝蜜最少加工保鲜工艺

正交试验与BP人工神经网络模型优选菠萝蜜最少加工保鲜的工艺条件。以贮藏时间及感官评分为指标,结合正交试验与人工神经网络方法,考察CaCl_2浓度、壳聚糖浓度、气调包装成分及比例对贮藏保鲜工艺的影响。BP神经网络模型优化工艺为CaCl_2浓度0.30%,壳聚糖浓度0.75%、气调包装成分及比例5%CO_2+15%O_2+80%N_2;正交试验优选的工艺条件为CaCl_2浓度0.30%,壳聚糖浓度0.50%、气调包装成分及比例5%CO_2+15%O_2+80%N_2;前者的感官评分高于后者。     

不同气体比例对金枪鱼气调解冻及贮藏期间保鲜效果的影响

为减缓解冻过程及解冻后金枪鱼品质劣化,研究金枪鱼在不同气体比例条件下解冻及后续贮藏期间的品质变化。采用6种不同气体比例(100%O_2、20%O_2+80%N_2、60%O_2+40%N_2、40%O_2+60%CO_2、20%O_2+60%CO_2+20%N_2、40%O_2+40%CO_2+20%N_2),在4℃冷藏条件下对金枪鱼进行解冻及贮藏,以汁液流失率、pH值、色泽、嫩度、硫代巴比妥酸反应物值、高铁肌红蛋白含量、挥发性盐基氮、菌落总数等理化指标的变化为依据评价金枪鱼的品质变化。结果表明:气调解冻对金枪鱼的色泽影响较明显,并且气调包装有利于金枪鱼贮藏期间的保鲜,其中组4(40%O_2+60%CO_2)金枪鱼气调解冻及贮藏期间保鲜效果最好。     

酸性电解水联合气调包装对鲜切生菜品质的影响

以鲜切散叶生菜为研究对象,在4℃贮藏条件下研究酸性电解水联合气调包装对其保鲜效果的影响。研究表明:与pH 2.3、有效氯含量为60 mg/L的酸性电解水联合空气包装(21%O_2+1%CO_2)的对照组相比,电解水联合气调包装可以有效抑制鲜切生菜微生物的生长繁殖,延缓水分和VC的损失,抑制新陈代谢和可溶性固形物含量的减少,抑制叶绿素的分解,延缓褐变黄化的速度,保持鲜绿的外观,维持鲜切生菜的感官品质。采用酸性电解水联合气调包装(5%O_2和10%CO_2)可以将鲜切生菜的货架期从6~9d延长到15d,并保持良好的感官品质。     

保鲜方式对冷鲜猪肉挥发性风味物质的影响

以冷鲜猪肉为对象,研究保鲜方式对冷鲜猪肉挥发性风味物质的影响。通过气相色谱-质谱联用(gas chromatography-mass spectrometer,GC-MS)分析发现,70%O_2+20%CO_2+10%N_2气调保鲜和60%CO_2+40%N_2气调包装冷鲜猪肉的挥发性风味物质的种类和含量都明显低于真空保鲜的产品,通过电子鼻主成分分析(principal component analysis,PCA)和线性判别分析(linear discriminant analysis,LDA)可以发现,当真空保鲜的冷鲜猪肉发生变质时,气调保鲜产品的挥发性风味物质与其有显著差异,说明气调保鲜可有效地延缓蛋白质和脂肪的氧化降解。     

高氧气调包装对绿芦笋POD活性及其基因表达的影响

以"Grande"绿芦笋为研究对象,采用空气包装、100%O_2、80%O_2+20%CO_2、60%O_2+20%CO_2+20%N_2这4种气调包装(Modified-atmosphere packaging,MAP)方式贮藏绿芦笋,定期测定过氧化物酶(Peroxidase,POD)活性,同时采用QRT-PCR技术测定POD基因相对表达水平,探讨高氧MAP对POD活性及其基因相对表达水平的影响。结果显示,贮藏30 d,经80%O_2+20%CO_2MAP后的绿芦笋POD活性,低于空气MAP(P0.05),POD基因相对表达水平始终低于空气MAP,在贮藏12～24 d时,二者差异有统计学意义(P0.05)。因此高氧MAP可有效降低绿芦笋POD活性和抑制基因表达,为进一步研究气调保鲜机制和产业化应用提供了理论支持。     

低氧高二氧化碳贮藏环境对马铃薯品质的影响

为探索低氧高二氧化碳贮藏环境对马铃薯贮藏品质的影响,本实验研究了5%(体积分数,下同)O_2+2%CO_2、5%O_2+4%CO_2、5%O_2+6%CO_2、5%O_2+8%CO_2及5%O_2+10%CO_2的气体环境对马铃薯在4℃和10℃贮藏120 d期间主要营养品质、外观品质及生理品质的影响。结果表明:5%O_2+2%CO_2的贮藏环境可延缓贮藏过程中还原糖含量的上升,并且保持良好的薯皮色度及抑制膜脂过氧化反应,保护膜系统的相对完整性,延缓多酚氧化酶活力的升高,从而延缓马铃薯块茎的衰老;而5%O_2+10%CO_2的贮藏环境反而会引起还原糖的大量积累,但可明显抑制块茎的发芽。本研究结果可为加工型马铃薯的贮藏提供理论依据。     

Microbiological and visual quality of fresh-cut cabbage as affected by packaging treatments

Microbiological behavior of fresh-cut cabbage as affected by packaging treatments including high oxygen (MAP1: 70 kPa O₂+15 kPa CO₂/balanced N₂), low oxygen (MAP₂: 5 kPa O₂+15 kPa CO₂/balanced N₂), and moderate vacuum (MVP), in combination with gas permeable (LDPE) and barrier (Ny/PE) films, was investigated. Spoilage bacteria and pathogens were inoculated on shredded cabbage, and observed for viable cell counts during storage at 5°C. Overall population of the tested bacteria was noticeably reduced in MAP1 with Ny/PE, but was little influenced by MAP2. However, the inoculated bacteria in MVP with Ny/PE significantly increased or leveled off. In sensory evaluation, the barrier packages maintained better visual quality compared to the permeable. Results indicate that packages with high O₂ and CO₂ in the barrier film showed considerable microbial inhibition without deteriorating visual quality. Therefore, it can be applied as a promising tool to secure microbial safety of fresh-cut vegetables at refrigerated temperatures.     

The role of peroxidase on the antioxidant potential of fresh-cut ‘Piel de Sapo’ melon packaged under different modified atmospheres

The effects of different initial in-package O₂ and CO₂ concentrations (2.5 kPa O₂ + 7 kPa CO₂, 10 kPa O₂ + 7 kPa CO₂, 21 kPa O₂, 30 kPa O₂ and 70 kPa O₂) on peroxidase activity, vitamin C content, total phenolics and antioxidant capacity of fresh-cut ‘Piel de Sapo’ melon have been investigated for 14 days at 4 °C. The radical scavenging activity of fresh-cut melon strongly increased after 9 days storage related to a synthesis of phenolic compounds, especially under 2.5 kPa O₂ + 7 kPa CO₂ atmospheres. Low O₂ levels best maintained vitamin C and phenolic content during the storage. However, stressful too-low O₂ and high CO₂ levels induced an important increase of peroxidase activity under 2.5 kPa O₂ + 7 kPa CO₂ atmosphere, which was directly related to changes of vitamin C throughout storage. Therefore, 70 kPa O₂ atmospheres are proposed to prevent anaerobic conditions during storage of fresh-cut melon and thus, reduce wounding stress and deteriorative changes related to high peroxidase activity in tissue.     

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     

Innovative active modified atmosphere packaging improves overall quality of fresh-cut red chard baby leaves

The antimicrobial effects and quality changes of O₂, He, N₂ or N₂O-enriched active modified atmosphere packaging -MAP- (100 kPa initial gas partial pressure) compared to a chlorinated −100 mg L⁻¹ NaClO- passive MAP (control) in fresh-cut Red Chard baby leaves up to 8 days at 5 °C were studied. High O₂ MAP (>85 kPa O₂) inhibited natural microflora growth during 7 days at 5 °C. Regarding control treatment, no differences for He and N₂O-enriched MAPs on microbial growth were found although control samples were previously disinfected. Initial total phenolics content (613 mg ChAE kg⁻¹ fw) increased up to 61-93% after 6 days at 5 °C under O₂, He, and N₂-enriched MAPs. Vitamin C content decreased up to 67% after shelf life in control samples while lower decreases were monitored in samples stored under non-conventional MAPs. He-enriched MAP preserved the total chlorophylls content throughout shelf life. After 8 days at 5 °C the overall sensory quality of all treatments showed a moderate decrease while still being scored at the limit of usability. In conclusion, He and O₂-enriched MAPs are useful tools in the preservation of fresh-cut Red Chard quality.     

EFFECT OF MODIFIED ATMOSPHERE PACKAGING ON COLOR STABILITY AND ON MICROBIOLOGY OF TURKEY BREAST MEAT

The effects of several modified atmospheres (100% O₂, 100% N₂, 100% CO₂+ O₂ scavenger, and 25% CO₂ 9% N₂ 66% O₂) and vacuum on the color stability of turkey were studied. Microbiological examinations were performed at days 0, 7, 14 and 21. pH and pigment content measurements were performed at days l and 2, respectively. Color coordinates were determined at intervals of 2, 5, 7, 11, 14 and 21 days storage in the CIELAB system (1976). Meat kept under vacuum and 100% CO₂+ O₂ scavenger treatment showed the highest a* values color stability (p < 0.05) and the lowest rate of myoglobin oxidation (p < 0.05). The level of microbiological contamination of turkey breast meat stored with 100% CO₂+ O₂ scavenger was the lowest. Conditioning breast turkey meat with 100% CO₂+ O₂ scavenger or under vacuum would improve the color stability during storage.     

Microbial Changes in Shredded Iceberg Lettuce Stored under Controlled Atmospheres

Our purpose was to determine initial microbial populations in shredded Iceberg lettuce (Lactuca sativa L.) cv ‘Great Lakes’, and to study their changes under different controlled atmospheres. Lettuce was shredded, washed, disinfected, water rinsed and centrifuged before being stored for 12 days under air, 3% O₂, 3% O₂+ 5% CO₂ or 3% O₂+ 10% CO₂. Microbiological analysis and assessment of visual quality were carried out every 3 days. No human pathogens were found. Controlled atmospheres had little or no effect on the microbiological populations studied. A 3% O₂+ 10% CO₂ atmosphere maintained acceptable visual quality of lettuce, without appreciably affecting microbial development.     

Effect of oxygen on aroma volatiles and quality of fresh-cut cantaloupe and honeydew melons

Cantaloupe and honeydew melon cultivars were processed and stored under a high oxygen passive modified atmosphere packaging (MAP) or reduced oxygen controlled atmosphere (CA; 5 kPa O₂ + 10 kPa CO₂ and balance N₂) for 14 days at 5 °C. Atmosphere did not affect softening rate or soluble solids content and had a negligible effect on colour. Volatile compounds known as flavour-important in melons were extracted using stir bar sorptive extraction (SBSE) and quantified via GC–MS. Acetate esters increased more in MAP than in CA. Non-acetate esters increased markedly in both cultivars and storage types. Alcohols were more abundant in honeydew than in cantaloupe. Aldehydes decreased during storage in both cultivars and storage types. Lower O₂ availability under CA conditions likely suppressed some of the esters relevant to the aroma of fresh-cut melon. Results suggest that package O₂ levels are more important in determining aroma than other quality attributes of fresh-cut melon, and high O₂ levels may be required to reveal desirable aroma compounds.     

Antioxidant phytochemical and fruit quality changes in mango (Mangifera indica L.) following hot water immersion and controlled atmosphere storage

Tropical fruits such as mangoes destined for import into the United States are commonly required to have a thermal treatment against invasive pests, which could be combined with controlled atmosphere (CA) storage to prolong shelf life and preserve fruit quality. Changes in antioxidant phytochemicals and resultant quality during storage and ripening were investigated in fresh mangoes, as influenced by application of CA in combination with a hot water immersion quarantine treatment (46 °C for 75 min). Mature-green mangoes with or without a hot water treatment, were held in air, 3% O₂ + 97% N₂, or 3% O₂ + 10% CO₂ + 87% N₂ and evaluated for external quality and phytochemical differences after storage for 2 weeks at 10 °C and after subsequent ripening in air at 25 °C. Visible appearance of anthracnose during ripening was effectively inhibited by the hot water treatments combined with CA. Concentrations of gallic acid and numerous hydrolysable tannins and their resultant antioxidant capacity were unaffected by the hot water treatment, while total polyphenolics naturally decreased throughout fruit ripening, regardless of hot water treatment or storage atmosphere. However, the overall decline in polyphenolic concentration was inhibited by the CA treatments, as a result of delayed ripening. Quality parameters such as flesh colour and titratable acidity provided supporting evidence that the CA conditions helped to delay fruit ripening.     

Effectiveness of ozone in combination with controlled atmosphere on quality characteristics including lignification of carrot sticks

Fresh-cut carrots were ozonized in water (1:2 w/v; @ 200 mg O₃/h) for 10 min and stored under controlled atmosphere (CA) conditions (2% O₂, 5% CO₂ and 93% N₂) at 6 ± 1 °C and 85% RH for up to 30 d. Ozonation was found to reduce lignification and maintaining the keeping quality of fresh-cut carrots during CA storage. The maximum decrease in respiration and ethylene emission rates were obtained by the combination of CA with ozone followed by CA alone and ozonation compared with the control samples kept under low temperature (6 ± 1 °C). Significant (p < 0.05) reduction in ascorbic acid, carotenoids and oxidative enzymes such as polyphenol oxidase (PPO) and peroxidase (POD) were observed due to ozonation and CA storage. The control of lignification by ozone in synergy with CA was characterized by decrease in L∗ values. The results highlighted the positive role of ozonation in combination with CA storage in controlling lignification and microbial spoilage of carrot sticks.     

Effect of Modified Atmosphere Packaging on Shelf-Life of Iced Fresh Hake Slices

Shelf-life of hake slices (Merluccius merluccius) stored in the ice state (2±1°C) under modified atmosphere packaging (MAP) conditions was determined by measurements of pH, total volatile bases (TVB) and trimethylamine (TMA) content, mesophilic and psychrophilic bacterial counts, malonaldehyde content, exudation, protein functionality and sensorial analyses (colour and odour). The effect of different gas mixtures were evaluated: (1) 40% CO₂, 50% N₂, 10% O₂; (2) 60% CO₂, 30% N₂, 10% O₂; (3) 40% CO₂, 30% N₂, 30% O₂; (4) 60% CO₂, 10% N₂, 30% O₂ and (5) air (control). Important differences were found between MAP-stored and air-stored hake slices. Shelf-life of hake stored under MAP conditions was two-fold extended. Bacterial growth wasinhibited, increases of pH, TMA and TVB were reduced, and alterations inprotein functionality were delayed, and off-odours were not noted in MAP-stored hake slices after 21 days storage. Significant correlations were found between TMA content and total viable count (TVC), as well as between apparent viscosity and exudation. Hake slices could be stored in the ice state under MAP conditions for about three weeks without an important loss of quality. Fish freshness, handling practices and initial bacterial load have an important influence of shelf-life of hake.