Modelling the gas exchange rate in perforation-mediated modified atmosphere packaging: Effect of the external air movement and tube dimensions

Perforation-mediated modified atmosphere packages control the gas exchange rate and thus the internal atmosphere composition by judicious choice of dimensions of small tubes in perforations in an otherwise hermetic container. The aims of this work were (i) to study the effect of external turbulence on the gas exchange rate through small perforations, (ii) to develop a mathematical model to predict the effect of tube dimensions and hydrodynamic conditions on gas exchange coefficients, and (iii) validate the model developed during the storage of shredded carrots. Different hydrodynamic conditions in the controlled temperature room due to the storage temperature settings (5, 10 and 15 °C) and PVC tubes dimensions (diameter from 1.5 to 4.5 mm length from 2.0 to 6.0 mm) were tested. Results showed that, as expected, hydrodynamic conditions (induced turbulence) and tube diameter had a significantly positive effect on the mass transfer values, whereas tube length had a negative effect. The permeability ratio between CO₂ and O₂ was 0.83 ± 0.01 and did not show any pattern with the factors tested. The gas exchange coefficients increased with decreasing temperature, as the establishment of lower temperatures implied a frequent air movement. A mathematical model to estimate changes of gas composition over time as a function of tube dimensions and hydrodynamic conditions was developed and found to have good predictive abilities. The model was validated during the storage of shredded carrots at 5 °C in PM-MAP, showing a good agreement between the experimental and predicted gas exchange of O₂ and CO₂. The results obtained in this work showed that hydrodynamic conditions of the cold storage room affected the gas exchange rate in PM-MAP.     

冷鲜肉高氧气调保鲜包装研究

为延长冷鲜肉的货架期,本研究以PP材质托盘盛装,PP膜封盒,充入不同比例的气体成分对冷鲜肉进行气调包装.在温度4℃、湿度80％的恒定条件下,分别研究了25％ O2＋ 75％ CO2、45％O2＋55％ CO2、65％ O2＋ 35％ CO2的3种不同气体组分的气调包装对冷鲜肉的感官指标、色度、pH值和挥发性盐基氮含量等指标的影响,并且通过与大气对照组的对比,对冷鲜肉气调保鲜包装第6天的保鲜效果进行雷达直观定性分析.结果表明,65％O2＋35％ CO2组气调包装的保鲜效果明显好于其他实验组,冷鲜肉的货架期延长了6天.     

气调保鲜包装机气体比例混合器的研究

综述了气调保鲜包装机中气体比例混合器的原理、类型及气体混合配送技术,研究了应用气体比例混合器的新技术实现不同比例气体的调节与组合,连续不断地供给气调保鲜包装机,适应各种被包装物品的保鲜包装要求。     

基于宏基因组分析气调保鲜卤鸭掌中微生物污染

摘 要:目的 研究气调保鲜卤鸭掌中微生物污染的菌相组成及主要致病菌、致病基因与耐药基因的相关情况。方法 从市场采购气调保鲜鸭掌样品,提取DNA,检测DNA浓度,测序、注释,菌种鉴定与丰度分析等,并检验菌落总数。结果 菌落总数结果为1200CFU/g,符合食品安全国家标准要求,DNA浓度为6.54ng/μL存在一定层度微生物污染;采用宏基因组研究方法分析菌相组成,共测出48种微生物,诺卡氏菌丰度最高约75%,大肠杆菌、不动杆菌、慢生根瘤菌、盐单胞菌、克雷伯菌、沙门氏菌、弧菌丰度大于1%;比对SEED数据库,检出对稳态铜的抗性基因;比对KEGG数据库,发现13种代谢通路可感染宿主;比对ARBD数据库,发现4个多重耐药性基因,1个氯霉素抗性基因。结论 宏基因组结合传统微生物研究方法可有效分析样品中微生物状况,并能从分子层面研究致病因子,以及耐药基因的传播机理,对于微生物污染防控,耐药基因传播阻断机制,有重要的借鉴性意义。     

Modified Atmosphere Packaging of Fresh Beansprouts

Freshly harvested beansprouts displayed a respiration rate of about 1 mmol O₂ kg⁻¹ h⁻¹ at 10°C which was strongly dependent on temperature, a 10-fold increase being observed every 16·5°C (z=16·5°C, ie Q₁₀=4·4). This commodity is also characterised by a high initial microbial load (about 10⁷ cells g⁻¹). During storage at various temperatures from 1 to 20°C, oxygen uptake rates dramatically increased with time and this phenomenon was well correlated with the development of aerobic microorganisms which reached 10⁹ cells g⁻¹ after 2 days at 20°C or 9 days at 1°C. Beansprouts were packaged in films, with permeabilities ranging from 950 to 200000 ml O₂ m⁻² day⁻¹ atm⁻¹, and stored at 8°C. Due to plant and microbial metabolism, oxygen concentrations decreased steadily within all packs until the onset of plant tissue decay. The latter occurred after 5–6 days with the least permeable films but did not occur within when the film permeability was over 100000 ml O₂ m⁻² day⁻¹ atm⁻¹. However, such films favoured brown discolouration, exudation texture and breakdown. The orientated polypropylene film (OPP) induced anoxic condition within 2 days and favoured anaerobic metabolism and necrosis of the sprouts. In all packages there was a rapid development of aerobic microorganisms and lactic acid bacteria that resulted in the accumulation of acetate and lactate and a decrease in pH. Thus, it clearly appeared that tissue decay was enhanced by microbial activity. At 8°C, 0·24 m² of film per kg of sprouts provided the optimal atmosphere composition (ie 5% oxygen and 15% carbon dioxide) when a film permeability of 50000 ml O₂ m⁻² day⁻¹ atm⁻¹ was used. These conditions allowed a shelf-life of 4–5 days.     

翡翠贻贝气调保鲜包装研究

采用涂布聚偏二氯乙烯的聚酯与聚乙烯复合薄膜袋(KPET/PE)气调包装翡翠贻贝,混合气体包括:CO2、O2和N2。选用5组气体配比(A:V(75%O2)/V(25%N2);B:V(50%O2)/V(50%N2);C:V(20%O2)/V(30%CO2)/V(50%N2);D:V(10%O2)/V(50%CO2)/V(40%N2);E:空气)进行包装并贮藏在5℃以下。在贮藏期间测定包装袋内气体浓度变化、需氧菌总数、TVBN和pH值,研究在不同气调比例包装条件下,翡翠贻贝的品质变化。实验结果表明:在贮藏温度为5℃条件下采用气调包装的样品,其需氧菌总数和TVBN等指标明显优于空气对照组。在5组气体比例中,以V(O2)∶V(CO2)∶V(N2)=10%∶50%∶40%的配气比例包装的保鲜效果最佳,其贮藏期比对照组空气包装延长3￣8d。     

Modified Atmosphere Packaging of Cut Belgian Endives

ABSTRACT: Modified atmosphere packaging of cut Belgian endives was simulated based on experimentally determined package and product parameters. Permeability of commercial packaging films was determined at 3 temperatures. The film permeability ratio for CO₂ and O₂ varied between 1.6 and 6. Respiration rate of cut Belgian endives stored under 10%O₂-10%CO₂-80%N₂ (optimal gas conditions) was measured at different temperatures. Initially, the activation energy for respiration rate was higher compared to the one for film permeability. After 3 d of storage, the E_a-value for respiration rate was similar to the E_a-value for film permeability. Simulations at constant temperature proved that none of the packaging films tested was suitable to maintain optimal gas conditions.     

微孔膜气调包装内外气体交换数学模型的建立

依据气体传质基础理论,基于Fick 定理建立微孔膜气调包装内外气体交换的数学模型。以无产品的微孔膜气调包装实验分析孔参数对包装内气体体积分数的影响,并验证数学模型。结果表明,孔径和孔数对包装内气体体积分数变化的影响显著,膜厚影响不显著,且模型预测值与实验数据吻合度较高。     

Evolution of the volatile compounds of ripened sausages as a function of both storage time and composition of packaging atmosphere

An experimental investigation was carried out to study the evolution of the volatile compounds of ripened sausages as a function of both storage time (time) and composition of packaging atmosphere (MAP). Ripened sausages, prepared at an industrial plant, were packed applying three different atmosphere compositions and were stored for three months. The obtained data evinced that the evolution of the volatile compounds was significantly related to the variable time more than to the variable MAP. The main volatile compounds were those derived from spices. Among them, Δ³-carene was the most abundant and a significant decrease was observed during storage (p < 0.05). The volatile compounds derived from lipid autoxidation showed generally a significant increase during storage, suggesting the raise of lipid oxidation also at low oxygen concentration. Moreover, octanal and nonanal were significantly influenced by the atmosphere composition, with the highest values in samples packed at the lowest CO₂ concentration.     

气调和乙烯对采后青梅果实保绿效果及生理的影响

本文研究了在25℃下,气调包装和乙烯吸收剂处理对青梅采后果实生理生化及保绿效果的影响。结果表明:气调包装和乙烯吸收剂处理均能抑制果实呼吸强度和乙烯释放量上升,延缓果实叶绿素含量和ASA含量含量降低,保持果实硬度,但以气调包装效果更佳。二者处理均能提高果实中SOD的活性,同时抑制了POD活性上升;抑制生成速率。以上结果说明二者处理可能是通过维持果实活性氧代谢平衡和抑制果实吸收强度和乙烯释放量来延缓叶绿素降解。-O2·     

Recent Application of Modified Atmosphere Packaging (MAP) in Fresh and Fresh-Cut Foods

Modified atmosphere packaging (MAP) has been applied in the food industry for about 90 years to extend shelf life and maintain quality of fresh and fresh-cut foods. Recently, MAP has experienced a rapid development in both scientific and industrial communities, which was one of the most appropriate and practical technologies for packaging fresh and fresh-cut produce. This paper reviews some recent developments of newly emerged MAP systems such as high-oxygen MAP, controlled MAP, and intelligent MAP and provides an overview of MAP applications for fresh and fresh-cut fruits, vegetables, mushrooms, meat, and aquatic products.     

自发气调包装对辣椒贮藏品质的影响

为探究不同自发气调包装对辣椒贮藏品质的影响,以\     

气调保鲜包装技术在食品包装中的应用

气调保鲜包装技术可调节不同比例的气体组合,适应多种被包装食品的要求,延长食品的保鲜期,能保证食品果蔬的原汁、原味、原貌。文中介绍了气调保鲜包装技术的原理以及在食品和果蔬等产品包装中的应用,探讨了其保鲜包装方法和特点。     

金枪鱼气调保鲜技术的研究进展

气调保鲜技术通过抑制微生物繁殖和降低氧化速率以达到延长水产品货架期的目的。在金枪鱼气调保鲜中,CO2的抑菌作用十分重要,O2对于肉色保持也必不可少,而经CO发色的肉制品是否可以食用国内外仍存在较大分歧。气调包装金枪鱼货架期的延长取决于贮藏温度、气体比例、包装材料、包装物体积比以及初始微生物的含量等因素,其中贮藏温度最为关键。气调包装对水产品货架期的延长明显优于空气包装。本文主要介绍了金枪鱼气调保鲜技术的研究现状,并指出可以从包装外形、气调包装和其他保鲜方法的结合,以及温度波动下气调包装是否能有效减损保质等方面进行今后的研究。     

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.     

An Integrated Approach to Factors Affecting the Shelf Life of Products in Modified Atmosphere Packaging (MAP)

The aim of this work was to analyze the main factors influencing the shelf life of peanut products in modified atmosphere packaging (MAP). Roasted and salted peanuts produced by three well-known commercial companies were presented as examples. Different types of packaging (multilayer laminated materials, cans) with different gas mixture composition (0-1% O₂, 1-3% O_2, 3-6% O₂) were compared. The main aim of shelf-life investigation is to ensure consumer acceptance of a product. Factors affecting the shelf life of products in MAP are presented as an integrated pyramid. All elements of this shelf-life pyramid should be analyzed and included during shelf-life investigations. This study indicates that estimation of the shelf life of a food is integrally related to its packaging (e.g., peanuts in MAP); both product conditions and the package as well as gas mixture composition should be considered.     

An Integrated Approach to Factors Affecting the Shelf Life of Products in Modified Atmosphere Packaging (MAP)

Abstract

The aim of this work was to analyze the main factors influencing the shelf life of peanut products in modified atmosphere packaging (MAP). Roasted and salted peanuts produced by three well-known commercial companies were presented as examples. Different types of packaging (multilayer laminated materials, cans) with different gas mixture composition (0–1% O₂, 1–3% O_2, 3–6% O₂) were compared. The main aim of shelf-life investigation is to ensure consumer acceptance of a product. Factors affecting the shelf life of products in MAP are presented as an integrated pyramid. All elements of this shelf-life pyramid should be analyzed and included during shelf-life investigations. This study indicates that estimation of the shelf life of a food is integrally related to its packaging (e.g., peanuts in MAP); both product conditions and the package as well as gas mixture composition should be considered.     

气调包装对杨桃贮藏品质的影响

以香蜜甜杨桃为材料,研究12℃条件下、非气调包装、被动气调包装(初始气体比例为21%O2+0%CO2+79%N2)和主动气调包装(初始气体比例为5%O2+5%CO2+90%N2)对杨桃果实保鲜效果的影响。结果表明:与非气调包装相比,被动气调包装和主动气调包装在一定程度上延迟了杨桃色泽的黄化,使果实的失重率维持在2%以内,果实硬度维持在0.4 MPa以上,3种包装在这3个指标的测量值上差异显著(P≤0.05)。对可溶性固形物、可滴定酸、VC的含量和pH值的维持效果来说,主动气调包装比被动气调包装的维持效果好,两者的差异极显著(P≤0.05)。被动气调包装与主动气调包装的总酚和类黄酮含量得到有效地维持,两者无显著差异(P≤0.05)。与非气调包装相比,主、被动气调包装都抑制了过氧化物酶的活力,使其达峰时间从25 d推迟到35d。果皮色泽、失重率和硬度可作为杨桃是否衰老的指标,非气调包装、被动气调包装和主动气调包装的杨桃的货架期分别为20～25 d,25～35 d和35～40 d。     

香菇气调保鲜包装工艺研究

以香菇为试验材料,研究1%壳聚糖涂膜结合不同气调包装工艺低温贮藏香菇的保鲜效果。分析了不同保鲜工艺对其感官品质、失重率、Vc含量变化、细胞膜透性等生理生化指标的影响。结果表明,采用1%壳聚糖涂膜结合314μm OPP/PE微孔膜气调包装的方法,可延长货架期到19d,并能较好的保持香菇的感官品质和营养价值。     

Modelling respiration rate of soybean seeds (Glycine max (L.)) in hermetic storage

The dynamic of oxygen (O₂) and carbon dioxide (CO₂) concentration was characterized in soybean (Glycine max (L.)) samples hermetically stored in glass jars at 15, 25 and 35 °C and 13, 15 and 17% moisture content (m.c., wet base). Two correlations were used for smoothing gas concentration in time: linear and exponential. Then, the respiration rate at each temperature and m.c. combination was calculated as storage time progressed and oxygen was consumed and two predictive models for respiration were proposed: Model I (temperature and m.c. dependent) and Model II (temperature, m.c. and oxygen dependent). It was observed that respiration rate increased with storage m.c. and temperature. However, respiration rate was not mainly affected by O₂ until a critical concentration limit of about 2% was reached. Respiration rates were from 0.341 to 22.684 mg O₂/(kgDM d) and from 0.130 to 20.272 mg CO₂/(kgDM d) for a range of storage condition of 13–17% m.c. and 15–35 °C temperature. The respiration rate of soybean seeds obtained in this study resulted significantly lower than the rates reported in the literature for other grains at similar temperature and a_w (water activity) storage condition. For hermetic storage simulations in which O₂ concentration is not expected to drop below 2%, the simplest model (Model I) could be used, but if the O₂ concentration of the hermetic system is expected to be depleted, Model I would under estimate the time at which O₂ is consumed, and thus a model with O₂ dependency is recommended instead (Model II).