Influence of cryogenic temperatures on food products and packaging during rail transportInfluence des cryotempératures sur les produits alimentaires et leur emballage au cours du transport par chemin de fer

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.     

Precooling of cylindrical food products

For homogeneous spherical produce numerically generated time-temperature data are used to develop a relationship between the Fourier number, Biot number, dimensionless radial distance and normalized temperature. This allows determination of thermal diffusivity through time-temperature measurements. The method is used to determine the thermal diffusivity of apples, oranges and portatoes. The results are compared with those from previous studies^1,2, and good agreement is observed.     

Storage lives of chilled and frozen fish and fish products

This Paper describes a meeting that was timely and clearly of wide international interest. It brought together people of diverse backgrounds — academics, Government research workers, inspectors, industrialists and others and, although no clear conclusions emerged, there was general agreement that the participants gained considerably from the information presented and discussed. It focussed attention on the areas where information is still lacking and hopefully it will have stimulated endeavours in one way or another to further our understanding of fish as food and thereby improve the quality available to the consumer.     

Literature reporting of shelf life data. What does it all mean?

This paper presents an analysis of reported shelf life data in the scientific literature, and a critique of the methods used to determine shelf life and the manner in which the data are reported.     

Refrigeration and the world's food supply — especially in developing countries

The reason for starvation today is poverty. Refrigeration can help the developing countries to export high value products. This helps to improve the economical situation and their buying power. Refrigeration can also help to reduce waste. Primitive distribution systems using refrigeration can be used at an early stage but the infrastructure is the limiting factor for introduction of modern transport equipment. Appropriate refrigeration technology is required, and the IIR should promote this by, for example, introducing an award for good proposals.     

Measuring the convective heat transfer coefficient while chilling carcasses

The importance of the heat transfer coefficient when chilling carcasses justifies its re-examination and work to its magnitude and variation. While the air velocity at the surface of carcass (with its rather irregular configuration) is an elusive quantity, the author demonstrates that the measurement of the transfer coefficient and its variation should be based on the rate of air flow over unit mass of carcass and on the rate of weight loss through evaporation.     

Comparison of conventional and automated refrigerated storage systems

High rise warehouses with automated storage and retrieval systems (AS/RS) can frequently be justified as a viable alternative to conventional freezer storage. To determine viability, a design year data base must be developed and both conventional and automated system/facility options tested against this operational standard. To determine which alternative best suits design year requirements, a justification analysis must be completed. This analysis must address investment costs and total operational costs. Operational factors such as expandability, flexibility and maintainability must be considered. This Paper outlines a basic approach to the justification analysis required when considering high rise automated and conventional alternatives for refrigerated warehousing applications.     

Structured packing liquid holdup in cryogenic systems

Experimental results and a theoretical analysis are presented on structured packing liquid holdup under cryogenic conditions. The experimental tests were performed on a novel laboratory unit incorporating a gas lift pump to recirculate the cryogenic liquid in a flow visualization dewar. Holdup is measured by sensing the difference in level in the dewar when the liquid flow is shut off after a constant operation at a given liquid loading. A dimensional analysis is performed to identify the important system properties that affect the liquid holdup. The preliminary experimental data are compared against a correlation developed from the dimensional analysis.     

Comparative experiments on three-wall and one conventional road vehicle

In 1984 international research took place which compared the transport conditions of quick-frozen foods in thin-wall vehicles and conventional vehicles. This work was done at the request of the group of experts of the UNECE/TRANS/GE.11 in Geneva, Switzerland. In the Netherlands measurements have been carried out on three road vehicles — one conventional and two thin-wall vehicles — in the test station and on the road. The road transport involved taking a commercial cargo of frozen fish from Holland to Italy during the summer (July). Later on an additional test was performed in the test station with a fourth thin-wall vehicle at an ambient temperature of 30°C. The results show, that in the conventional vehicle, equipped with a bulk head and a ceiling air duct, and working on a temperature setting of −25°C, a maximum product temperature of −18°C could be maintained. The maximum temperature difference in the cargo was 6 K. Thin-wall vehicles appeared to have a temperature difference of 12 K between air inlet temperature and warmest product temperature. The maximum product temperature could be held below −12, −15 or −20°C, depending on the air distribution and, in particular, on the cooling power of the thermal appliance.     

Changes in sheath properties of rainbow trout eggs during cold and frozen storage

Rainbow trout eggs (V/VI Maier scale maturity stage) stored at 2 and −25°C were studied for hardness, lipid components, peroxides and conjugated diene and triene groups. The egg resistance to crushing after seven days of cold storage decreased from 87.3 to 66.0 g. The concentrates of free fatty acids, peroxides, diene and triene groups showed no tendency to increase. Changes in sheath resistance to crushing during frozen storage were significant, the resistance dropping from 87.3 to 30.0 g after 12 months of storage at −25°C. The temperature of −25°C inhibited lipolytic enzymes. Egg lipids were not oxidized before the third month of storage. After four months of storage at −25°C (hardness 46.5 g), the eggs were salted to determine the extent of hardness changes under the influence of sodium chloride solution and thermal treatment. Egg sheath hardness assays showed salting to result in hardness increasing from 46.5 to 85.0 g. Pasteurization reduced egg hardness, but the extent of reduction was not proportional to the duration of thermal treatment. Hardness reduction (down to 50.0 g) in the rainbow trout eggs during frozen storage has no detrimental effects on the suitability of eggs for delicatessen product manufacture.     

Prediction of freezing and thawing times for foods — a review

This communication presents a review of methods to predict the freezing and thawing times of foods. A bibliography of over 400 references was used.