Food science and engineering in the IIR

Refrigeration is one of the most important technologies used to extend the storage life of foods. Commission C2 of the Inter­national Institute of Refrigeration (IIR) aims to enhance and disseminate scientific and tech­nical knowledge and economic data concerning refrigeration as related to food science and engineering. This article examines the Institute’s main activities.

The International Institute of Refrigeration is a bilingual (English/French) scientific and technical intergovernmental organisation that aims to pool scientific and industrial know-how in all refrigeration fields, on a worldwide scale. The IIR’s mission is to promote knowledge of refrigeration technology and all its applications in order to address today’s major issues, including food safety, protection of the environment (reduction of global warming and protection of the ozone layer) and the advancement of the least developed countries (food, health). Members of the IIR include Member Countries, of which there are now 61. Member Countries take part in IIR activities via the commission members they select. There are also other IIR members: corporate or benefactor members (companies, laboratories, universities, etc.) or private (individual) members.

Food Science and Engineering

Commission C2 on Food Science and Engineering is one of the IIR’s ten commissions – other commissions address issues such as cryology, thermodynamics, energy, refrigerated storage and transport etc. Commission C2 specifically looks at how refrigeration may enhance the storage life of foods with respect to quality and microbial safety. Both fresh commodities as well as processed foods are considered. Whereas a whole array of technologies such as cooling, freezing, controlled and modified atmosphere storage is commonly used, the emphasis is not on the technology itself (as this is addressed by other commissions) but on the interaction between food and equipment with special emphasis on food quality and safety.

Conferences

Commission C2 organises conferences on a regular basis as a vehicle to disseminate knowledge amongst scientists and professionals. The conference topics may cover a large range, from the preservation of genetic resources, over post-harvest technology of fresh fruit and vegetables to modelling of quality. Often the commission may decide to co-sponsor conferences when refrigeration technology is involved in the conference theme.

Working parties

IIR Working Parties bring together specialists in order to work on specific themes. Their aim is to promote development and provide knowledge in these areas. They provide solutions to problems encountered and give recommendations. Members of Working Parties come from industry, University and research centre settings or are refrigeration practitioners.

Revision of Red Book

The so-called Red Book (‘Recommendations for the processing and handling of frozen foods‘) is a basic book on freezing that has been used as an invaluable resource by food engineers all over the world since its first publication in 1964. It gives an update on the principles of freezing, quick-freezing, storage and thawing of food, with due attention to physical, physicochemical, nutritional and biochemical aspects, as well as to microbiology, hygiene, packaging, transport, presentation and retail sale. It has been translated in different languages including Chinese. A Working Party has been established by Leif Bøgh-Sorensen of the Danish Institute for Food & Veterinary Research to prepare the fourth edition of the Red Book, due in 2005.

Data and models for refrigeration and freezing of foods

Most consumers are concerned about the microbial safety of their foods. In many countries appropriate hygienic quality control systems such as HACCP (Hazard Analysis Critical Control Points) are now mandatory. The HACCP methodology is essentially a qualitative approach to identify microbial safety risks and to suggest appropriate control measures. Temperature control is one of the most obvious and relatively easy-to-implement control activities at the manufacturing level. However, abuse may occur downstream in the cold chain and may promote growth of hazardous microorganisms. Novel, quantitative approaches such as predictive microbiology and microbial risk analysis may be used to evaluate the consequences of such temperature abuse and are gaining much attention in the food safety community. However, they rely on data concerning cold chain parameters such as refrigeration temperature, relative humidity, air velocity etc., which is often not available.

Also, although mathematical models have been used extensively for refrigeration engineering design purposes, advances in both computer hardware and numerical analysis have led to new tools for analysing heat and mass transfer during cooling and freezing processes. One such tool is Computational Fluid Dynamics (CFD). This is essentially the numerical calculation of fluid flow and related phenomena (such as heat and mass transfer) based on the fundamental conservation laws of physics in realistic geometries generated by Computer Aided Design (CAD) programs or three-dimensional (3D) computer visualisation tools. With input of physically meaningful properties and realistic conditions from measurement, CFD generates 3D contours and vector plots of all relevant variables (velocity, pressure, temperature, concentrations and heat flux). CFD is accurate and versatile but requires powerful computers and considerable expertise to obtain valid solutions for industry-relevant problems. CFD provides answers where experiments fail or are too expensive. However, there are still many unsolved problems such as the modelling of heat and mass transfer in stacks of produce, turbulence in porous media etc.

A Working Party has been set up to achieve the following:

• Establish a database of typical temperature-time profiles and other relevant parameters (relative humidity, air velocity, etc.) in the food refrigeration and freezing chain
• Review heat and mass transfer models and appropriate computational methods for the cold chain
• Present these results in a special issue of the International Journal of Refrigeration
• Make the database available via the IIR Web site
• Regularly update the database

Cold Chain Optimisation

Commission C2 also participates in a Working Party on Cold Chain Optimisation, chaired by Dr. Nevin Amos, Zespri, New Zealand. The emphasis is on the development of integrated models for the whole cold chain and the optimisation of the cold chain through these models with respect to food quality, microbial safety and energy usage. Special attention will be paid to links between food refrigeration and human health – particularly Crohn’s disease – by collaborating with medical scientists.

Other activities

One of the activities of the IIR is to distribute, on a regular basis, informative notes. These notes are aimed at industry decision makers and legislative bodies, to provide scientific information on selected topics. Commission C2 has recently issued such a note on the use of temperature indicators (TI) and time-temperature integrators (TTI) in the cold chain (http://www.iifiir.org/note_alim3_en.pdf). Both are simple, inexpensive devices – usually in the form of self-adhesive labels attached to products. The principle of both devices is a temperature dependent process that can be mechanical, chemical, physical, biochemical or electrochemical. The process results in an irreversible, measurable and often visual change, for example a change in colour. In a TI the change is typically triggered when some threshold temperature is exceeded. A TTI reacts to the cumulative time-temperature history of the product. It is clear that such indicators provide a powerful tool to monitor the cold chain. This may have a beneficial effect on both product quality and public health through the detection of temperature abuse. Several technologies are now commercially available and the advantages and disadvantages of the technology are discussed extensively in the informative note. Other notes cover topics such as Listeria monocytogenes in refrigerated foods and the role of refrigeration in worldwide nutrition.

More information

More information about the IIR and its activities can be found at www.iiriif.org