A simple model for the interaction between water vapour and oxygen transmission in multilayer barrier materials intended for food packaging applications

The low oxygen permeability of the ethylene‐vinyl alcohol copolymer, EVOH, is outstanding, but is also known to be very sensitive to moisture uptake and cannot be used as a monolayer packaging material. In this paper, theory is presented in order to calculate the average water activity of the EVOH layer at steady state and the corresponding oxygen barrier for different multilayer structures using various polymer types and layer thicknesses. Multilayer materials can be designed for different food packaging applications and storage conditions, in order to keep the relative humidity of the barrier below recommended 75%, by varying the thickness of the outside versus the inside protective layers and/or varying the water vapour transmission rate of the outside versus the inside layer. The conclusion reached is that to retain the optimal barrier properties and thereby the optimal protection of the food, asymmetric multilayer structures are necessary. Copyright ©2007 John Wiley & Sons, Ltd.     

Process of contaminant transfer through a food package made of a recycled film and a functional barrier

The process of the transfer of a contaminant through a package made of a recycled film in good contact with a virgin film playing the role of a functional barrier is studied. The two films being made of the same polymer, the contaminant diffuses within the two layers of polymer with the same constant diffusivity. Convective transfer of the contaminant takes place through the surface of the functional layer in contact with the food, while the other external surface is impermeable to it. The effect of the coefficient of mass transfer at the packaging-food interface on the rate of transfer of the contaminant to the food is especially studied. Dimensionless numbers are used, making the results general.     

Assessment of insulating package performance by mathematical modelling

A mathematical model has been developed in the present work to describe the temperature change in a typical insulated shipping container as a function of time. The model was created by combining steady state and transient models in a 2D geometry of a typical shipping container and was subsequently validated by an ice melt test and comparison of temperature change obtained from the model and experimental measurement. An excellent agreement was obtained between the computational model developed in this work and experimental results. In addition, a parametric study was also carried out to investigate various factors in controlling the insulation performance of the packaging. It was found that the model has capability of evaluating the effect of a wide range of packaging design parameters such as thermal conductivity, surface emissivity, packaging geometry, and sounding temperature.     

Migration of BHT through airspace in food package systems

In the system composed of a plastic package and a solid food, which are only partially in contact with each other, the migration of the plastic ingredient to the food may take place through the airspace between the package and the food unless the ingredient is non-volatile. This paper describes the migration of an antioxidant BHT(2,6-di-tert-butyl-4-methylphenol) from low-density polyethylene films containing BHT, or from pure BHT crystals used as a source of BHT vapour, to model foods such as casein and granulated sugar. The results obtained:

• i confirmed that the migration of BHT occurs from the film to the food even when they are separated completely by an airspace between them
• ii showed that the amount of migration increases with time and attains a practically constant value after a certain period, but the value and the time vary significantly with the food
• iii found that the BHT concentration in the film remains virtually unchanged at all times in the experiments carried out in this study, because the amount of BHT migration is very small compared with the total amount of BHT contained in the film initially
• iv elucidated the relation between the BHT concentration in the film and the equilibrium amount of BHT migration to the food. This result should be useful for the estimation of the amount of BHT migrating from a polyethylene package to a contained food.

     

Characterization of moulded‐fibre packaging with respect to water vapour sorption and permeation at different combinations of internal and external humidity

A moulded‐fibre packaging system was characterized under conditions simulating real‐life packaging of food. A steady‐state moisture flux through the moulded‐fibre packaging was generated by subjecting the system to different combinations of internal humidity [33–97% r.h. (0.33–0.97a_w of contents), RH(i)] and surrounding humidity [33–97% r.h., RH(e)]. The objective was to resolve whether a hygroscopic fibre material absorbs moisture proportional to the rate of moisture transport, and the moulded‐fibre material was thus characterized with respect to accumulation of moisture in the fibre material, water vapour transmission rate (WVTR) and permeability (k/x). These steady‐state properties showed significant asymmetry depending on direction of moisture transport. When moisture was transported out of the system [RH(i) > RH(e)] the fibre material adsorbed moisture to a considerable lesser extent compared to when moisture was transported into the system [RH(i) < RH(e)], just as (k/x) increased by 15–20%. Taking both directions of moisture transport into account, the moisture content of the fibre material depended largely on surrounding humidity, even at high internal humidity. Moisture contents ranged from 5.5 g/100 g dry fibre at RH(e) 33% r.h. to 16.4–25.1 g/100 g dry fibre at RH(e) 97% r.h. The observed asymmetry was shown to derive from the experimental set‐up and not from the material itself. A minimal theory based on the various transport steps in the experimental set‐up was proposed in order to qualitatively explain this asymmetry. The rate of moisture adsorption in moulded‐fibre was described by the normalized response function H(t). Response times to reach equilibrium moisture contents were 6 and 8 h for RH(e) 33 and 53% r.h., and 40 and 41 h for RH(e) 75 and 97% r.h. Copyright © 2004 John Wiley & Sons, Ltd.     

Active packaging as an opportunity to create package design that reflects the communicational,functional and logistical requirements of food products

The packaging of industrial food products is the most important means of transmitting a product's image and taste value. When the nature of its interface and its contents are the product of carefully planned imaging, the product has notable advantages in defining its image and product identity. Modern food trends dictate an ever‐increasing amount of services: The so‐called ‘functional packaging’ and ‘active packaging’ are prime examples of this service. The greatest innovation within this category of products consists literally of their interaction with food. These features create numerous fallbacks within all stages of the life‐cycle of a product, requiring a complex and multidisciplinary evaluation. The evaluation strategy of services which this packaging will offer to the consumer is still to be defined, and still to be identified within the key applications are the interests of the intermediary links of the production process. This requires the evaluation of the semantic and communicative aspects of the packaging which tend to be confused with the foodstuffs, the individualization of appropriate user profiles, control of logistical and location aspect of production, and a careful analysis of a comprehensive environmental balance, all issues that are parts of the objectives of the European project, Actipak. It is hoped, therefore, that the elaboration of these packaging systems will become a motive to try out a more knowledgeable and systematic design process for foodstuffs, in which innovative technology is used to provide effective benefits to the consumer. Copyright © 2000 John Wiley & Sons, Ltd.     

Permeability of naphthalene in different types of polymeric food packaging materials

The relative permeabilities of naphthalene through different types of common polymeric food packaging materials were determined by migration studies in a controlled environment. The results illustrate that polyolefins, such as low density polyethylene (LDPE), have a higher relative permeability than other polymers, such as polyethylene terephthalate (PET) or polyvinylchloride co-polymer (PVC). This was explained by the correlation between the permeability of the migrant and the glass transition temperature (Tg) of the different polymers, as well as their polarity.     

Prediction of overpressure required for seal integrity during sterilization of semirigid food and drug packages

Heat processing semi-rigid packages with a steam/air mixture requires an overpressure to ensure seal integrity. A method was developed to calculate the overpressure needed to ensure seal integrity, during thermal processing, of semi-rigid packages that contain a liquid food or drug. An equation was derived relating total retort pressure (steam and air) required during sterilization to retort temperature, product water activity and tensile seal stress at the sterilization temperature. The proposed method was tested, under commercial sterilization conditions (123–127°C for 30min), with individual packages containing a dilute saline solution. The method was found useful for predicting the total retort pressure (steam and air overpressure) needed to ensure seal integrity and to prevent leakage of packages.     

几种食品包装用塑料膜阻透性能比较

目的研究不同厚度、不同材质的食品包装用塑料膜透氧量、透湿量的变化情况,为食品包装在阻隔性方面的选材提供依据和指导。方法采用压差法和杯式法分别测试塑料膜的透氧量和透湿量。结果单层塑料膜随厚度的增加,透氧量和透湿量均减小,阻隔性能变好。相同厚度的PE,PET,BOPP,PA这4种单层塑料膜中,PA的透氧量最小,PE的透氧量最大,BOPP的透湿量最小,PA的透湿量最大。复合膜厚度增加,其透氧量、透湿量均减小,但减小幅度逐渐变小。塑塑复合膜外层材料厚度不变时,透氧量、透湿量随总厚度变化不太明显,EVOH塑料复合膜的透氧量值和透湿量值较小,通常在5以下,铝箔塑料复合膜的透氧量值和透湿量值均小于1。结论单层塑料膜PA的氧气阻隔性最好,PE的氧气阻隔性最差,BOPP的水蒸气阻隔性最好,PA的水蒸气阻隔性最差。复合膜中,塑塑复合膜的阻隔性主要取决于外层材料,铝塑复合膜的阻隔性最好,含高阻隔材料EVOH的塑料复合膜的阻隔性比普通塑塑复合膜好,其阻隔性可与铝塑复合膜媲美。     

A simplified environmental evaluation tool for food packaging to support decision-making in packaging development

Packaging developers in the food industry must consider several, sometimes conflicting, environmental requirements on packaging along with an already complex combination of marketing, logistics and production requirements. Existing methods for the environmental evaluation of packaging either focus on a limited amount of environmental packaging criteria (such as recyclability or renewable content) or rely on life cycle assessment methodology requiring expert competence. To support the food industry in their efforts toward developing product and packaging combinations that reduce the total environmental impact in food supply chains, this article presents a simplified environmental evaluation tool for food packaging. The presented tool was developed through an iterative process in a collaborative research project with the food industry. It evaluates packaging systems based on packaging criteria sorted into four areas that represent the life-cycle steps packaging material production, transport, household and end-of-life. A comparison of the tool results and screening LCA results for three packaging cases showed no major differences. From the practitioners' perspective, the main advantages of the suggested tool are that it does not require LCA-competence, that the required input data is commonly available in packaging development projects and that its overall structure invites several functions of the company to participate. The theoretical benefits of the suggested tool are that it allows for a parallel assessment of eco-efficiency and eco-effectiveness criteria in a life cycle perspective and that it considers littering risk as well as the influence of packaging on food waste in households     

BB/T 0030-2019《包装用镀铝薄膜》内容解读

本文系统解读BB/T 0030-2019《包装用镀铝薄膜》的相关内容,对生产企业的出厂检验和检验机构的产品检测具有一定的意义。     

High‐pressure processing effects on the mechanical,barrier and mass transfer properties of food packaging flexible structures: a critical review

Food products can be high‐pressure processed (HPP) either in bulk or prepackaged in flexible or semi‐rigid packaging materials. In the latter case the packaging material is subjected, together with the food, to high‐pressure treatment. A number of studies have been performed to quantify the effects of high‐pressure processing on the physical and barrier properties of the packaging material, since the integrity of the package during and after processing is of paramount importance to the safety and quality of the food product. This article reviews the results of published research concerning the effect of HPP on packaging materials. Copyright © 2004 John Wiley & Sons, Ltd.     

利用真空衰减法测试预包装食品的密封性

目的 预包装食品的密封性关系到食品质量与安全。本文针对预包装食品目前普遍采用水检气泡法时灵敏度不足的问题,采用真空衰减法检测食品包装的密封性。方法 分别利用2种不同检测技术对市面上55款预包装食品样品进行密封性检测,并根据包装类型、封合方式、包装规格等不同分类方式将测试数据进行综合比较分析。结果 水检气泡法测试成本低,可明显地指示出泄漏位置,但方法灵敏度较低,且无法准确定量;真空衰减法可在不破坏原有包装的情况下,大幅度提高检测灵敏度,并得到定量数据,但无法准确指示泄漏点位。结论 真空衰减法可以作为水检气泡法的有效补充方法在实际工作中使用。     

Measurement of permeability for packaging films to d-limonene vapour at low levels

A method that utilizes permeation cells in conjunction with gas chromatography was developed to measure permeation of d-limonene vapour through packaging materials at very low gradient concentrations. The same method, when properly adjusted, can be used to determine the effect of temperature and relative humidity on permeation. The suitability of the method for its intended use was demonstrated by generating permeation data for polyester (Mylar) and oriented polypropylene (OPP) films at d-limonene vapour concentration gradients as low as 0.54 ppm. The ability to measure permeability at such low concentration levels, where the permeability coefficient approaches a virtually constant value, is of considerable importance. The permeation behaviour of packaging materials at even lower concentrations, most typical of foods, can be obtained by extrapolation. Thus, flavour loss through the package and shelf-life can be estimated in a more reliable manner.     

The effect of high‐pressure food processing on the sorption behaviour of selected packaging materials

The sorption behaviour and flavour‐scalping potential of selected packaging films in contact with food simulant liquids (FSLs) (ethanol and acetic acid solutions) were evaluated after high‐pressure processing (HPP). The films used were monolayer polypropylene (PP), a multilayer (polyethylene/nylon/ethylene vinyl alcohol/polyethylene: PE/nylon/EVOH/PE), film and a metallized (polyethylene terephthalate/ethylene–vinyl acetate/linear low‐density polyethylene: metallized PET/EVA/LLDPE) material. D‐limonene was used as the sorbate and was added to each of the FSLs. After HPP treatment at 800 MPa, 10 min, 60°C, the amount of D‐limonene sorbed by the packaging materials and the amount remaining in the FSL was measured. Untreated controls (1 atm, 60°C and 40°C) were also prepared. Extraction of the D‐limonene from the films was performed using a purge/trap method. D‐limonene was quantified in both the films and the FSL, using gas chromatography (GC). The results showed that D‐limonene concentration, in both the films and the food simulants, was not significantly affected by HPP, except for the metallized PET/EVA/LLDPE. Significant differences in D‐limonene sorption were found in comparison with the control pouches. The results also showed that changes in temperature significantly affected the sorption behaviour of all films. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of functional barrier thickness for a food package with recycled polymer

Food packaging films can be made of bilayer polymers, one being a virgin polymer and the other the recycled polymer. The mathematical treatment of the diffusion of a contaminant with constant diffusivity when the two polymers are of the same nature is considered. Moreover it is considered that the contaminant does not pass through the external surfaces of the packaging. The effect of the relative thicknesses of the virgin and recycled polymers is presented using dimensionless numbers so as to establish general results. Master curves of the profiles of concentration of contaminant developed through the packaging are drawn as are the kinetics of contaminant transfer into the virgin polymer and the increase in its concentration at the external surface of the virgin polymer. From the master curves thus obtained it is possible to determine in any typical case the time necessary for a given transport of pollutant to occur.     

方便壳/皮回收的环保型食品包装袋设计

为解决目前大量休闲食品产生的垃圾带来环境污染的社会问题,本文在现有食品包装袋基础上提出一种方便壳/皮回收的食品包装袋设计技术方案,并针对不同人群的心理需求结合工效学原理,设计了壳/皮回收食品袋多种外形结构方案及相应的制作方案,经市场初步应用效果良好,且有利于引导人们养成良好的卫生行为习惯。     

Specific migration of caprolactam and infrared characteristics of a polyamide/polyethylene composite film for food packaging under conditions of long-term storage before use

Caprolactam is the monomer typically used for the production of polyamide 6 films. Originating from incomplete polymerization reactions, caprolactam can remain part of the final food packaging and has the potential to migrate from the plastic packaging into the packed good. For film and food producers as well as for end users, it is of great interest that the conformity of a film with migration limits is ensured over its lifetime and that environmental conditions do not affect the migration behavior inadequately. In this work, we have investigated the long-term storage characteristics of a polyamide/polyethylene (PA/PE) film over a storage period of 40.5 months with respect to the specific migration rate of caprolactam. Within statistical indicators, this rate is stable over the complete storage period. Different exposure conditions were applied to the same PA/PE film to accelerate the aging process. Alterations under forced aging conditions (elevated temperature and ultraviolet radiation) were studied by Fourier transform infrared (FTIR) spectroscopy to detect possible chemical changes in the polymer bulk and, by the use of the attenuated total reflection method, on the sample surface. The film was subjected to an extraction study to verify the results obtained using FTIR. Additionally, mechanical tensile tests were carried out. Indication for alterations regarding caprolactam under the different storage conditions were found. The results clearly show that photo-oxidative conditions led to changes in the chemical and mechanical properties of the film. New chemical species occurred caused by degradation of the polymers and their contribution to chemical migration is discussed.     

新欧盟指令对塑料食品接触材料产业影响及对策研究

[目的]为深入了解、系统分析欧盟塑料食品接触材料及制品新指令及其影响,[方法]对塑料包装材料的欧盟新指令和现行强制性国家标准进行了比较研究,[结果]明晰了两个技术法规之间的显著差异。[结论]分析认为,按照WTO规则,技术法规的差异必然造成对食品塑料包装及相关产业的深刻影响。并从遵循国际贸易规则、提升产业层次等角度,针对性地提出应对对策。     

Comparison of Various Packaging Films for Mango Export

This study compared the effects of the use of various types of packaging films in maintaining quality, preserving bioactive compounds and extending shelf life of the ‘Nam Dok Mai’ mango. The principal techniques for maintaining the quality of mangoes are based on modified atmosphere packaging using highly gas‐permeable films and an ethylene‐removing mechanism. The films studied were non‐perforated highly gas‐permeable film, non‐perforated ethylene‐absorbing highly gas‐permeable film (HNPE), micro‐perforated highly gas‐permeable films (HMP) and common non‐perforated polyethylene film (LNP). These films were compared with non‐packaging treatment, which served as a control (C). Gas composition (O₂, CO₂ and C₂H₄) in the package headspace was monitored during storage at 12°C. The quality of mangoes were assessed by weight loss, colour (L* a* b*), texture, total soluble solids, titratable acidity, total phenolics, total flavonoids, ethanol concentration and sensory quality. Equilibrium‐modified atmospheres of 5 kPaO₂ + 5 kPaCO₂ and 4 kPaO₂ + 5 kPaCO₂ were achieved in the non‐perforated highly gas‐permeable film and HNPE packs, respectively. Carbon dioxide accumulation was observed in the HMP and LNP packs where CO₂ reached 17 and 10 kPa, respectively, after storage for 10 days. The shelf life of mangoes was extended to 40 days with HNPE, 35 days with HNP, and 30 days with HMP, as compared with 20 days with control and 5 days with LNP. HNPE, the film incorporated with fine particles of mordenite framework inverted‐type zeolite with ethylene‐absorbing ability, could further extend the shelf life of mangoes in addition to modified atmosphere packaging alone. Copyright © 2011 John Wiley & Sons, Ltd.