坚果仁铝塑复合膜包装结构的性能比较与剖析

目的坚果仁铝塑复合膜包装易出现袋体泄漏、复合膜剥离分层、热封不良等问题,导致产品在保质期内变质,需监测坚果仁包装材料的关键性能并熟知改进工艺,保证优质包装材料的选用。方法以3种不同材质及厚度的坚果仁铝塑复合膜包装为例,测试并对比分析3种包装材料的揉搓前后的氧气透过率、剥离强度、耐热性、热封强度、密封性能等关键参数。结果 3种包装材料中,1#样品各方面性能均较优,2#样品仅在耐揉搓性方面稍差,3#样品各方面性能均较差。结论坚果制品企业在选用铝塑复合膜包装材料时,应在充分考虑内容物的特性、保质期、存储条件等因素的基础上,注重包装材料厚度、各层膜质量及热封工艺,并及时监控包装材料性能,从而筛选出阻氧性、物理机械强度及密封性能较好的包装材料。     

Effects of modified atmosphere packaging conditions on quality preservation of powdered infant formula

The effect of different modified atmospheres (100% N₂, 100% CO₂, 70% N₂/30% CO₂, 50% N₂/50% CO₂, and air) on the quality preservation of powdered infant formula was investigated by a storage test at 30°C. Metal can packages of 400 g per unit were stored for 493 days with periodic measurements of package gas composition and product quality attributes, which included peroxide value (POV), pH, titratable acidity, bifidobacteria count, hydroxymethylfurfural content, surface colour, and solubility. In the air package, POV as an oxidative quality index increased highly along with oxygen concentration decrease, reaching a maximum of 58.7 meq/kg lipid at 350 days. Compared with the air package, POV increase of the product was significantly lower, with all the O₂‐excluded modified atmosphere packages showing a maximum of 28.5 to 29.3 meq/kg at 350 days. Packages of high CO₂ concentration experienced a pH decrease and an acidity increase of the stored product caused by dissolution of CO₂. The count of bifidobacteria in the product was maintained higher after 119 days in the package of 100% CO₂ than in the other packages. Hydroxymethylfurfural content showed a slight increase after an initial period of slight decrease, with little difference among the package treatments. There were no significant changes in product solubility and surface colour during storage. Considering that the high CO₂ atmosphere helps the survival of bifidobacteria and protects the product from oxidation without negative effects on the other quality attributes, it is suggested for use in packaging of powdered infant formula.     

Non‐intrusive Measurements of Headspace Gas Composition in Liquid Food Packages Made of Translucent Materials

The increase in chilled food consumption requires enhanced food safety and quality assurance. Food deteriorating processes are affected by the presence of oxygen, combined with factors such as time and temperature. To slow down deterioration processes and prolong shelf life, traditional packaging methods are being replaced by modified atmosphere packaging, for example. Oxygen, which is naturally present in the headspace of most food packages, is then reduced and controlled. Many sensing techniques for food quality assurance have been developed; however, almost all are intrusive, increasing the complication level and causing sample waste. The purpose of this paper is to introduce a non‐intrusive technique [gas in scattering media absorption spectroscopy (GASMAS)] for measuring gas composition in the headspace of liquid food packages. The GASMAS method uses diode laser absorption spectroscopy combined with diffuse light propagation to analyse gas located inside solids and liquids. By illuminating the package from the outside and analysing the scattered light that emerges, the absorption from the gas inside the headspace can be studied.The GASMAS technique was evaluated on a series of carton packages with a high‐quality orange juice and a nitrogen headspace. A clear variation in oxygen content was measured for samples with different storage times. The results demonstrate the possibility of using the GASMAS method for non‐intrusive quality measurements in food products and packaging. They also indicate the potential for the non‐intrusive quality assurance applications without waste of samples. A further development of the technique could include ‘in‐line’ quality control of packed food items throughout the food packaging supply chain. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of the gas/product ratio and CO2 concentration on the shelf-life of MA packed fish

Rainbow trout and Baltic herring fillets were gas packed at two different gas/product ratios and two different CO² concentrations. Two reference samples were used; one frozen and one vacuum packed. Changes in gas composition in the gas packages, microbial and sensory quality, K values and drip formation of the fillets were investigated during storage at 2°C. A gas/product ratio of 100 ml/100g gas package was as effective as a vacuum package in preserving the microbial quality of fish and a gas/product ratio of 40ml/100g gas package was as effective as a vacuum package in preserving the sensory quality of fish.     

Oxygen permeance: a method applied to modified atmosphere packages containing fresh plant foods

A method to determine the oxygen content and oxygen permeance of composite packages is described. It can be used for packages comprising materials of different permeability, or ones that have pinhole or sealing defects. The method requires little specialized apparatus and is well‐suited to the determination of the temperature coefficient of permeance for a package. The results are relevant to the design and quality control of modified atmosphere packaging for respiring fresh vegetables. Copyright © 1999 John Wiley & Sons, Ltd.     

The effect of packaging materials and oxygen on the colour stability of sliced bologna

The aim of the study was to determine the effect of packaging materials with different oxygen permeability, residual oxygen concentration in the package and light upon discoloration of the surface of sliced bologna. The packaging material caused significant differences in the discolouration of vacuum-packed, sliced bologna. The surface colour of sliced bologna packed in films with an oxygen transmission rate lower than 10cm³/m²/24h/atm was not affected by illuminated storage. Packages of sliced bologna with 0% oxygen in the head space showed good colour stability after 28 days of illuminated storage at 4 C. The discolouration of bologna was almost directly proportional to oxygen concentration in the package. Bologna stored in a high oxygen concentration developed more off-odour; 1% and 2% oxygen in the packages caused higher worst spot colour, discolouration and off-odour scores after 3 days of storage.     

Effect of light and oxygen transmission characteristics of packaging materials on photo‐oxidative quality changes in semi‐hard Havarti cheeses

Changing transmission characteristics of food packaging materials by colouring the materials may be a suitable way of reducing photo‐oxidative quality changes. This study proved that packaging in black laminates provided the best protection of Havarti cheese, followed by a white laminate. However, transparent packaging materials did not protect the product in the critical wavelength range, i.e. 400–500 nm, and changes in colour and odour were already notable after few hours of exposure to fluorescent light. Additionally, secondary oxidation products, hexanal, 1‐pentanol, and 1‐hexanol, were formed in cheese packaged in transparent or semi‐transparent packaging materials. The expected effects of oxygen transmission were difficult to evaluate, due to high residual oxygen levels in the packages. Copyright © 2002 John Wiley & Sons, Ltd.     

Predicting changes in oxygen concentration in the headspace of nitrogen flushed packages by the ambient oxygen ingress rate method

The ambient oxygen ingress rate (AOIR) method is an alternative/supplementary method to Ox‐Tran for measuring the oxygen transmission rates of packages. The AOIR method facilitates high‐capacity testing of packages under realistic food storage conditions, on the one hand, and on the other hand provides the possibility to predict the oxygen concentration over time in packages flushed with nitrogen at the time of packaging. The predicted oxygen concentration values showed good agreement with experimental values for flexible packages stored over a period of 91 days at 23°C and 38°C. The prediction of the oxygen concentration in­nitrogen‐flushed packages may be a useful tool, e.g. in shelf life studies, in the selection of the optimal food package as regards to oxygen protection and within quality control purposes. Copyright © 2002 John Wiley & Sons, Ltd.     

菠菜微孔膜气调保鲜包装的试验研究

微孔膜气调包装技术是一种有效控制与调节包装内部气氛的方法.采用微孔膜气调保鲜技术包装菠菜,测量菠菜在贮藏过程中包装盒内的O2含量、外观、失重率、色差及叶绿素含量的变化,探讨微孔膜气调包装保鲜技术对贮藏菠菜的保鲜效果,并以无微孔密封包装为对照.结果发现,微孔膜气调包装能更好的维持菠菜的形态与品质.     

本征型聚酰亚胺膜气体分离性能的研究进展

包装内环境气氛对产品的性能具有重要的影响。选择合适的包装材料,控制包装内环境气氛的成分与含量,可有效延长产品的储存时间与使用寿命。为了实现良好的包装内环境气氛控制效果,包装材料需具备合适的气体分离性能。聚酰亚胺因其优异的气体分离性能、热稳定性和结构可设计性等特点受到关注,但气体渗透-选择性的平衡问题限制了其广泛应用。梳理了聚酰亚胺气体分离膜性能的研究进展,重点阐述了如何通过分子结构设计实现聚酰亚胺致密膜与微孔膜的性能调控,并对聚酰亚胺基气体分离膜材料的发展进行了展望。     

火炸药产品用包装物现状及发展趋势

目的总结我国火炸药产品用包装物的现状及发展趋势。方法梳理火炸药产品包装物应具有的基本功能,分析国内火炸药产品包装物及其标准现状,指出现有包装物及其标准存在的问题,总结未来火炸药产品用包装物的发展趋势。结果我国火炸药包装物采用的苏式箱包装、木箱包装和纸桶包装等3种形式,虽然能够满足火炸药产品贮存、运输的要求,但其在结构、材质、加工工艺及使用等方面落后的现状,逐渐暴露出不少问题;火炸药包装物标准使用年限长,至今未换版,在使用过程中也存在一定的争议。结论优化包装物的材料和结构,适应火炸药和弹药的自动化、智能化制造需要是未来火炸药产品包装物发展的重要趋势。     

Oxygen‐ and light‐barrier properties of thermoformed packaging materials used for modified atmosphere packaging. evaluation of performance under realistic storage conditions

The oxygen transmission rate (OTR) of packaging materials used for modified atmosphere packaging (MAP) of chilled products varies extensively with temperature, relative humidity (RH) and material thickness after the thermoforming of packages. Two different polymer combinations were studied: APET/PE (tray) and PA/PE (lid). A temperature reduction of 8°C (in the interval 7–23°C) caused an OTR reduction of 26–48% depending on material type, degree of thermoforming and RH. A 2–3‐fold increase in OTR was observed for PA/PE film when measured at 100/100% RH compared to 0/100% RH, whereas the APET/PE trays were not affected by RH. Increased OTR was observed as a result of material thinning; however, the increase was not always directly proportional to the degree of material thinning. Even very small amounts of oxygen have, in combination with light exposure, significant effects on oxidative quality deterioration of many products. Consequently, the changes in OTR observed in this study emphasize the necessity of evaluating the performance of packaging materials under realistic storage conditions, in order to estimate the real oxygen content of a chosen package solution. The light transmission through the packaging material was found to be reduced to 0–30% (300–800 nm) by dyeing of the lid and/or addition of labels. Thus, it is easy to protect the products from light, at least partly. Copyright © 2005 John Wiley & Sons, Ltd.     

Simple models for evaluating effects of small leaks on the gas barrier properties of food packages

A detailed theoretical analysis and calculations were made for providing a simple and explicit means to evaluate the effects of small leaks on the barrier properties of food packages. Small leaks, such as pinholes and channel leaks, were approximated as cylindrical pores with diameters of 50–300 μm. The first part of the current study proposes a simple mathematical model based on Fick's law of diffusion, which accounts for both the gas leakage across small leaks and the gas permeation across package walls. The model uses an effective permeability that depends on leak dimensions, type of diffusing gas, type of packaging material and gas conditions around the leak ends. In the second part of the study, three practical cases are presented to illustrate the application of the proposed model in examining the significance of leaks. These demonstrate in a simple and explicit manner that for LDPE packages: (a) leaks affect the oxygen transfer more than the water vapour transfer; (b) leak effects are more significant at lower storage temperatures; and (c) that for high gas barrier packages, the effect of leaks is very important and should not be neglected. The model can be also used to arrive at conclusions about the significance of leaks in other packaging situations (e.g. other than LDPE packaging materials) and to correct the shelf‐life estimation of gas‐ and water vapour‐sensitive foods for errors from package leaks. Copyright © 2003 John Wiley & Sons, Ltd.     

多层U形A瓦楞结构材料的共面力学性能

目的 定量化研究了不同包装厂家生产的无菌砖产品包装质量。 方法 采集了 3 种不同的无菌砖包装样品,通过层次分析法,建立了无菌砖包装质量评估方法,并检测了产品包装质量,对外观质量视觉缺陷率 PDR 值进行了统计和分析。 结果 甲、乙、丙 3 家产品中,甲产品外观质量最好,产品缺陷少,产品稳定性好,丙产品其次,乙产品最差。 鼓肚是影响无菌砖包装外观质量的主要影响因素。在置信水平 95% 下,甲产品的正态区间估计精确度最高,丙产品其次,乙产品最差;在相同区间估计精确度时,甲产品的可靠程度最高,丙产品其次,乙产品最差。 结论 对产品的包装质量进行了评估,为食品生产企业全面有效地管理和控制产品包装,以及分析和选择包装供应商提供了科学依据。     

Effect of Storage in a Low Oxygen Gas Atmosphere on Colour and Sensory Properties of Pork Loins

The objective of this study was to examine the quality characteristics of packaging materials and packaging units, and the viability and acceptability of the colour and sensorial properties of fresh pork meat during storage in low oxygen and high carbon dioxide modified atmosphere packaging up to 16 days at two temperatures (0°C and 4°C), as well as the sensorial properties of cooked meat. Packaging materials had good mechanical and barrier properties and were suitable for packaging in selected atmosphere. The concentration of oxygen during the whole storage period was less than 0.5% at both temperatures. The proportion of red colour (a*) was successfully maintained although the colour was slightly darker (L*) and the sensory value was lower when evaluated at the end of the storage period. Based on the obtained results and discussion, it can be concluded that samples packaged in a modified atmosphere with 40% CO₂ and 60% N₂ can be stored at 0°C for 15 days and at 4°C for 10 days. Samples had a good sensory quality until the 16th day, with the best results achieved on the 7th day. Copyright © 2013 John Wiley & Sons, Ltd.     

The influence of packaging materials on the dissolved oxygen content of probiotic yoghurt

The health benefits of probiotic functional foods have been widely reported. However, manufacturers face great challenge in guaranteeing delivering beneficial numbers of viable probiotic bacteria through to the end of the product shelf life. The oxygen toxicity of some probiotic species has been shown to contribute to reduced viable counts. The packaging system favoured by manufacturers may play a negative role, promoting oxygen uptake in the product. The research detailed herein evaluates the performance of current packaging materials and an alternative, oxygen‐barrier material. Commercial stirred‐type probiotic yoghurt was evaluated for dissolved oxygen content over a 6 week period from manufacture to expiry date. The results indicate a rising level of dissolved oxygen in the yoghurts over time. The distribution of oxygen throughout the product was also examined by measuring concentrations in two lateral positions, at three different depths. It was found that oxygen was not distributed homogenously, but was in significantly different concentrations (p < 0.05) at most sampling points. At some locations (near packaging weak spots), readings were approaching saturation, hardly an environment suited to the survival of the anaerobic and probiotic Bifidobacterium species. Yoghurt stored in packaging materials with improved gas‐barrier properties was also tested, displaying a decrease in dissolved oxygen levels during storage. It was concluded that using packaging materials with greater gas‐barrier properties would help remove a hurdle to the viability of the probiotic bacteria within the food. Suggestions for further steps, such as the addition of an oxygen‐scavenging technology, are also made. Copyright © 2002 John Wiley & Sons, Ltd.     

微孔膜包装内外气体交换的理论研究

为有效地提高包装膜的透气率,基于原包装膜而进行后加工制孔是近年来采用的主要技术手段之一.探讨了该类型微孔膜的透气机理,基于气体的渗透与粘性流动理论,建立微孔膜硬质盒包装、袋包装内外气体交换模型.理论分析了包装型式、微孔参数对包装内气份变化的影响.结果表明:设置微孔可显著地提高包装内外气体的交换速率;包装型式对包装内气份的变化有影响但不显著;包装膜孔隙率、微孔孔径显著地影响包装内气份变化速率,且孔径大小对包装内气份变化的影响更为显著.     

葡萄贮运过程中跌落与振动损伤的试验分析

目的 以巨峰葡萄为试验对象,研究在贮运过程中跌落冲击机械损伤,以及振动疲劳累积对其生理品质产生的影响。方法 在现有贮运包装条件下对葡萄进行不同高度的跌落试验,得到跌落高度对葡萄力学特性的影响。在相同高度下,对葡萄进行不同包装的试验验证,得到新型减振包装对葡萄力学特性的影响,并使用模拟运输振动试验台和六度空间振动试验台进行试验,模拟实际运输路况下不同包装对葡萄生理品质的影响。结果 研究发现,新型减振包装在2种振动疲劳累积试验下,质量损失率比普通包装减少了27.07%和21.42%,表面损伤系数减少了20.11%与17.61%。结论 可为葡萄设计合理的包装方式和运输方式提供理论依据。     

Packaging materials for fermented milk: effects of material crystallinity and polarity on food quality

The ability of a packaging material to protect the food product and extend its shelf‐life depends on several material properties. In this work the effects of material crystallinity and polarity on the quality of fermented milk were studied. The fermented milk is a high‐quality Swedish product, similar to yoghurt. The quality of the food product was determined as a function of storage time by containing the liquid in pouches of different materials. The material crystallinity was varied by using very low‐density polyethylene, high‐density polyethylene and aluminium laminate as packaging materials. Aluminium was used on account of its ‘100%’ gas‐tightness. The polarity was varied by comparing an aliphatic polyketone with polyethylene of similar crystallinity. The carbon dioxide (CO₂) and oxygen (O₂) contents in the headspace of the pouches were determined. The food quality was determined by measuring whey syneresis, viscosity and the content of desired Bifidobacteria, as well as of undesired yeast and mould. A trained taste panel determined the degree of acidity and of the sparkling taste. It was found that the content of CO₂ increased and that of O₂ decreased in the pouches with increasing degree of crystallinity and increasing polarity. The sparkling taste of fermented milk was a clear function of the headspace CO₂ content. The data presented here could thus be used to ‘design’ a package for a desired sparkling taste of the fermented milk by selecting a certain material crystallinity. Whey syneresis, viscosity and content of Bifidobacteria were found to be independent of pouch material. While the degree of whey syneresis and the viscosity increased with increasing storage time, the content of Bifidobacteria slowly decreased. The content of yeast and mould in the liquid was below the existing limit values for foodstuffs. The degrees of acidity and sparkling taste were highest for the liquids contained in aluminium and polyketone pouches, although the differences in acidulous taste between the various pouch materials were small. Copyright © 2001 John Wiley & Sons, Ltd.