Temperature fluctuations and quality deterioration of chilled cod (Gadus morhua) fillets packaged in different boxes stored on pallets under dynamic temperature conditions

A study was carried out to evaluate temperature variation and quality deterioration of packaged cod fillets as influenced by the box type used and their position on pallets under dynamic temperature storage. Storage life of thermally abused fillets was compared to that of fillets stored at steady temperature. Thermal performance of fish boxes, made of corrugated plastic on one hand and expanded polystyrene on the other hand, was also compared. Fillet temperature at multiple positions on the pallets along with environmental temperature and humidity were monitored during storage. Differences in product temperature of up to 10.5 °C were recorded on the thermally abused pallets stored for 6.4 h at mean ambient temperature of 18.5 °C. A reduction in storage life of 1.5-3 days was observed depending on the box position on the abused pallets compared to steady temperature storage.     

Assessment of technical and environmental performances of wheat‐based foams in thermal packaging applications

This paper presents an assessment of the technical and environmental performance of a wheat‐based foam (WBF) and bio‐composite for shipping chilled products. The thermal conductivity of the WBF was found to be higher than that of polyurethane foams commonly used in high‐value insulation packaging, but close to that of low‐density (expanded polystyrene) EPS foams and significantly lower than that of polyethylene (PE) foams, which are typically used in thermal packaging of foods. The insulation performance of a simple cool box constructed from both the WBF and EPS sandwich panels without the use of any refrigerant was studied experimentally. The comparison demonstrated that the performance of the WBF cool box was comparable to that of the EPS counterpart. Two industrial case studies were conducted on WBF cool boxes with refrigerants in comparison with PE or EPS counterparts. The WBF cool boxes had comparable thermal performance to the EPS and PE counterparts on the basis of identical foam thickness. The performance of the WBF cool boxes was also simulated with finite element (FE) modelling. Good agreement was achieved between experimental data and the FE prediction. The model was then used to assist cool box design. WBF cool boxes made from renewable raw materials are inherently biodegradable and may be used as an alternative to those based on polymer foams in thermal packaging applications. Life‐cycle assessment (LCA) was used to investigate environmental profiles of cool boxes made with WBF, EPS and PE foams. The WBF cool boxes offer substantially lower global warming and abiotic depletion potentials than equivalent cool boxes made from petrochemical foams. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of food container depth on the quality and yield of superchilled and iced Atlantic salmon

Insulated food containers of different sizes are commonly used to preserve the quality of perishable fresh fish products during transport and storage. The aim of the study was to explore the effects of packaging solutions with various depths on the quality of iced and superchilled farmed Atlantic salmon (Salmo salar). Insulated containers of different depths (32, 42, and 60 cm) and 17-cm deep expanded polystyrene (EPS) boxes were used to simulate transport and storage of the fish. The fish quality was evaluated after 4, 10, and 14 days of storage, where measurements on drip loss, texture, cooking yield, sensory evaluation, water and lipid distribution, and characteristics analysis in the fish muscle by nuclear magnetic resonance (NMR) spectroscopy were performed. Increased container depth from 32 to 42 cm increased the drip loss of superchilled salmon from 2.4% to 3.1% after 10 days of storage at −1°C. Iced storage of salmon for 10 days in EPS boxes resulted in less drip loss (0.5%) compared with superchilled salmon (1.5%) stored in EPS. The NMR analysis, sensory evaluation, texture analysis, and cooking yield did not reveal any major differences between salmon stored in containers of different depths. Iced storage increased pressure marks as compared with non-iced, superchilled storage in insulated containers. The results indicate that transport of whole salmon in reusable insulated plastic containers with a depth of 60 cm is possible without major quality changes observed for up to 10 days.     

Packaging for freshness and the prevention of discoloration of fish fillets

Fillets of various kinds of fish are currently packed in thin films (e.g. polyvinyl chloride) for sale at supermarkets; however, these fillets are not necessarily fresh or of good quality. Packed fillets must be certified for safety, freshness and quality, because sensory judgement is difficult. In order to understand how the freshness and colour of red fish meat can be retained, the methods of packaging were examined. It was known that for freshness the packed fillets must be kept at a low temperature, but discoloration of red meat could not be prevented by this alone. However, discoloration of red-meat fish, such as yellowtail and oceanic bonito, can be prevented by packing with nitrogen gas (N₂).     

Performance comparison of thermal insulated packaging boxes,bags and refrigerants for single‐parcel shipments

A range of packaging solutions exists for products that must be kept within a specific temperature range throughout the supply‐and‐distribution chain. This report summarizes the results of studies conducted over a span of 2 years by the Consortium for Distribution Packaging at Michigan State University. Thermal insulation packaging materials such as expanded polystyrene, polyurethane, corrugated fibreboard, ThermalCor^® and other composite packaging such as thermal insulating bags were studied. Phase change materials such as gel packs were also evaluated. Properties such as R‐value, melting point and heat absorption were examined and are reported. Copyright © 2007 John Wiley & Sons, Ltd.     

Influence of the Preservation Process on the Quality of Carp Fillets

An investigation was carried out on the microbiological quality of carp fillets linked to slaughtering methods, variation in temperature, storage time and packing as well as recording the main bacterial flora (total aerobic bacteria, Enterobacteria and Pseudomonas sp. and lactic acid bacteria). The results of this study showed the following. (i) The working room temperature (5–18°C) and dipping of the fillets in ice water did not have any influence on the microbiological quality of the carp fillets. However, for industrial purposes it would be more adequate to work at low temperature. (ii) The packaging process (air, vacuum or modified atmosphere) had significant effects on the microbiology of the fillets. (iii) Only those fillets under a modified atmosphere offered a shelf-life of 10 days or more (up to 14 days). (iv) MA packaging with 50% CO₂ gave the best results with regard to limiting microbiological growth. (v) Storage of the fillets at a temperature higher than 3°C should be prohibited as well as potential breaks in the cold chain.     

Method to estimate the consumption of ice during fish storageMéthode d'estimation de la consommation de glace au cours de l'entreposage du poisson

The amount of ice needed for the storage of fresh fish is economically important especially in warm climates. It is affected by the insulation of the fish boxes and containers and by the procedures used in the handling and transporting of iced fish. This paper describes a simple method to estimate ice consumption during fish storage. The method was tried with plastic boxes containing hake (Merluccius hubbsi) when ice losses were caused by heat transfer due only to natural convection. It can be used also to test any kind of box or container, and can give valuable indications with other heat transfer conditions.     

Extension of soil thermal conductivity models to frozen meats with low and high fat content

Thermal conductivity models of frozen soils were analyzed and compared with similar models developed for frozen foods. In total, eight thermal conductivity models and 54 model versions were tested against experimental data of 13 meat products in the temperature range from 0 to −40 °C. The model by deVries, with water+ice (wi) as the continuous phase, showed overall the best predictions. The use of wi leads generally to improved predictions in comparison to ice; water as the continuous phase is beneficial only to deVries model, mostly from −1 to −20 °C; fat is advantageous only to meats with high fat content. The results of this work suggest that the more sophisticated way of estimating the thermal conductivity for a disperse phase in the deVries model might be more appropriate than the use of basic multi-phase models (geometric mean, parallel, and series). Overall, relatively small differences in predictions were observed between the best model versions by deVries, Levy, Mascheroni, Maxwell or Gori as applied to frozen meats with low content of fat. These differences could also be generated by uncertainty in meat composition, temperature dependence of thermal conductivity of ice, measurement errors, and limitation of predictive models.     

Influence of cryogenic temperatures on food products and packaging during rail transport

Six commercially packaged frozen food products were subjected to simulated railway shock and vibration conditions and manual handling abuse at both cryogenic (−70°C) and non-cryogenic (−18°C) temperatures. The amount of package and food product damage under different temperatures and levels of abuse were determined. The effects of cryogenic temperatures upon sensory and various analytical quality attributes of the food products were examined. The test results indicated that frozen food can be shipped at cryogenic temperatures in railcars equipped with cushioned draft gears with minimal product or packaging damage, provided there is not excessive manhandling abuse.     

Effect of packaging materials and storage conditions on bacterial growth,off‐odour,pH and colour in chicken breast fillets

A comparison was made of the effect of different packaging materials on bacterial growth, off‐odour, pH and colour of chicken breast fillets stored at 4°C. For one of the packaging materials, the effects of temperature (4°C and 8°C) and initial oxygen present (0%, 2% and 4%) on bacterial growth, off‐odour, pH and colour in chicken breast fillets were also evaluated. Chicken breast fillets stored in the packaging material with the highest oxygen transmission rate (OTR) measured at actual storage conditions had the highest bacterial growth and the highest degree of off‐odour. Chicken breast fillets stored in packaging material mainly consisting of expanded PET had similar bacterial growth and off‐odour as in the barrier display film (BDF) packages, despite a smaller headspace volume and lower initial concentration of CO₂. No differences in discoloration and pH of the chicken breast fillets, due to storage temperature and amount of initial oxygen present, were found when one of the packaging materials was studied. In the early phase of the storage period, Pseudomonas spp. constituted the majority of the total viable counts, while after about 12 days, lactic acid bacteria dominated. At the end of the storage period, both Pseudomonas spp. and Enterobacteriaceae were present in high numbers. Significant differences in counts of Brochothrix thermosphacta were only obtained with initial presence of oxygen. The storage temperature had greater impact on microbial growth and off‐odour than the initial presence of oxygen in the packages. Copyright © 2004 John Wiley & Sons, Ltd.     

Acceptability of frozen stored consumer fish products

Wide range testing is reported of customer acceptability of various fish products after varying periods of frozen storage at −18°C. Four products of cod, breaded fillets, glazed fillets, fillet fingers and minced fingers, were tested by trained assessors and by groups of students in Colleges of Home Economics after storage periods of up to one year. Some trends were apparent, but in general the acceptability to the consumers remained essentially unchanged even after 1 year at −18°C.     

Phase change material for the thermal protection of ice cream during storage and transportation

Ice cream is a very temperature sensitive product and temperature variations during the storage and distribution steps may result in a reduction of quality. It is possible to improve the ice cream storage and transportation conditions by using an additional packaging with a low thermal diffusivity. This paper studies a phase change material (PCM) packaging and compares its performance to a polystyrene packaging configuration. The impact on temperature fluctuations and ice crystal size distribution was characterized experimentally during long term storage and temperature abuse. The results show that the use of an additional PCM packaging has a significant impact on the final quality of the product by keeping ice cream temperature stable and close to the phase change temperature of the PCM material. These results were compared with the insulation material results and discussed, showing that a material with a buffering heat capacity can be more efficient to reduce temperature fluctuations than a low conductivity material, and that the same results can be usually obtained with a much thinner layer of material.     

石墨烯改性相变聚氨酯发泡材料传热特性研究及仿真

目的 提升无源冷链物流中保温容器的保温性能,减少或取消短途冷链运输中蓄冷剂的使用量.方法 将石墨烯改性相变大胶囊与聚氨酯发泡材料共混,制备石墨烯改性相变聚氨酯发泡材料,研究石墨烯的添加对其导热系数和保温性能的影响,并基于COMSOL Multiphysics对石墨烯改性相变大胶囊和石墨烯改性相变聚氨酯发泡材料的传热过程进行有限元模拟.结果 在常温状态下,石墨烯的添加会增加石墨烯改性相变聚氨酯发泡材料的导热系数;在冷藏工况下,石墨烯改性相变聚氨酯发泡材料的导热系数随石墨烯添加量的增加而降低,石墨烯改性相变聚氨酯发泡材料制备的保温容器的系统热阻随石墨烯的增加而升高.通过有限元模拟可发现,石墨烯的加入能够提升相变大胶囊的导热系数,同时能够减缓升温平台阶段的升温速率;在跨越平台区后,即内部相变大胶囊完全融化后,石墨烯会提升保温材料的导热系数,从而降低保温容器的保温效果.结论 制备的石墨烯改性相变聚氨酯发泡材料能够在设计使用时间内提升保温容器的保温性能,该材料在需要冷藏的生鲜果蔬短途无源冷链物流领域具有广阔的应用前景.     

BWBZX-1保温包装箱设计与验证

目的根据某产品性能特性设计BWBZX-1保温包装箱,并进行验证。方法首先提出BWBZX-1保温包装箱的设计方案,然后通过数值模拟分析结构材料热物性参数对包装箱的温度场和传热特性的影响,用以对初设包装箱结构进行优化,最后通过环境试验进行验证。结果产品、包装箱内外壁、底板、法兰、底座材料不易变更,只宜优化上保温层、下保温层和连接件的热物性参数,使最终包装箱温度场满足了产品使用要求。结论 BWBZX-1保温包装箱温度场数值模拟结果与实验温度实测结果相符较好,经过温度场数值模拟和温度实验验证,BWBZX-1保温包装箱保温性能满足设计指标要求。     

Investigation of dry ice blockage in an ultra-low temperature cascade refrigeration system using CO2 as a working fluid

Dry ice blockage in a CO₂-solid-gas-flow-based ultra-low temperature cascade refrigeration system is investigated experimentally by a visualization test and a system study of the liquid CO₂ blew into an expansion tube through a Throttle needle valve. The visualization test shows that dry ice sedimentation occurs in low flow velocity and the dry ice formation makes the heat transfer behavior of CO₂ complicated. The sedimentation also occurs at low condensation temperature and low heating power input. Based on the present investigation, it is found that the present ultra-low temperature cascade refrigeration system is better to work at heating power input above 900 W and condensation temperature above −20 °C. At suitable operating condition, the present ultra-low temperature cascade refrigeration system has been shown the capability of achieving ultra-low temperature −62 °C continuously and stably.     

The influence of cryostructure on the creep behavior of ice-rich permafrost

Unconfined constant stress creep (CSC) tests were performed in order to look at the influence of cryostructure on the creep behavior of ice-rich undisturbed permafrost soils and remolded frozen soils within the temperature range from − 1 °C to − 2 °C. Undisturbed ice-rich permafrost soils were sampled from a Pleistocene age yedoma or “ice-complex” permafrost deposit in Interior Alaska. Cryostructure or the pattern of ice inclusions within a frozen soil is a direct indicator of the geologic and cryogenic genesis of permafrost soils. The data indicate that cryostructure influences the creep behavior of permafrost soils. Undisturbed soils with massive cryostructure showed higher induced creep strains and minimum strain rates than the more ice-rich undisturbed soils. Remolded soils with massive cryostructure experienced significantly lower creep strains and lower strain rates than the undisturbed soils. Deformation rates increase rapidly above a threshold stress value for remolded soils. From an engineering viewpoint, use of creep rates from remolded soils is non conservative and under predicts the creep rates of undisturbed soils. The orientation of ice lenses can facilitate motion along the ice lens–soil contact. Similarly, folding of ice lenses may occur, thus inducing anisotropic lateral strains. The ice facies tested indicate that for the temperature and stress range tested, ice creeps at a slower rate than frozen soils.     

Practical mathematical model to predict the performance of insulating packages

Thermal insulation is used in a variety of applications to protect temperature‐sensitive products from thermal damage. Several factors affect the performance of insulating packages. These factors include the packaging material, the geometry of the package, the geometry of the product, and the degree of contact between the product and the package. In this study, a comprehensive model which includes all of these factors was developed to predict the performance of the insulating package. First, an equation was derived for the calculation of the thermal resistance of a multilayered wall. The wall resistance was then used in a mathematical model which included the aforementioned factors. Basic heat transfer principles covering conduction, convection and radiation were applied to the model and the package heat penetration rate was calculated. Based on this model, several factors affecting the performance of the insulating package were discussed. Examples of the use of this model for ice requirement calculations were also included. Copyright © 2007 John Wiley & Sons, Ltd.     

Linear elastic constitutive relation for multiphase porous media using microstructure superposition: Freeze-thaw soils

The constitutive relation derived in our previous work based on the microstructure superposition technique is implemented here for three-phase microstructure configuration to study the mechanical behavior of freeze-thaw soils. Three scenarios were considered for the frozen soils: frozen soil consisting of only two solids, soil skeleton and ice; frozen soil with soil skeleton, ice, and void; and frozen soil consisting soil skeleton, ice and pores saturated with fluid. The frozen soil studied is Alaska frozen soil mainly consisting of clay and silt particles at temperature about −10 °C. The effective elastic constants were calculated for the media under each scenario using two sets of elastic constants of soil skeleton (clay mineral). The modeled results were compared with Hashin-Shtrikman's upper bound solution and the experimentally measured data. In addition to be able to model the mechanical behavior of freeze-thaw soils, the derived constitutive relation, as indicated in the results of this study, could also be used as a tool in determining the microstructure of freeze-thaw soils by measuring the elastic constants of soil skeleton, the elastic properties and unfrozen water content of the media.     

聚酰亚胺/羰基铁粉吸波包装材料性能分析

目的 制备聚酰亚胺(PI)/羰基铁粉(CI)复合膜并探究其性能,以改变微波加热过程中的加热方式.方法 主要通过红外光谱、扫描电镜、力学性能、透氧透湿和微波转热测试分析其性能.结果 聚酰亚胺与羰基铁粉是物理结合;当羰基铁粉质量分数超过25％时,开始发生团聚;当羰基铁粉质量分数为20％时,弹性模量最小;当羰基铁粉质量分数为15％时,透氧透湿系数最低;随着羰基铁粉含量的增加,复合膜在微波加热下升温和常温下降温的速率增加.结论 PI/CI复合膜能够吸收部分微波转热能,是一种新型的吸波包装材料,为微波加热用包装材料的设计提供了新思路.