Skip to main content

PREDICTIVE MODELLING OF MICROBIAL GROWTH SURVIVAL IN FOODS

Objective

The overall objective was to introduce young scientists to the concept of modelling microbial growth responses, to develop databases of the responses of key microorganisms to the processes and conditions to which they are exposed in food processing. In parallel, awareness of the concept would be promoted to facilitate use of the database. It was necessary to standardize and coordinate the accumulation of relevant experimental microbiological, and to develop new approaches to modelling those microbial responses so that microbial death, survival or growth can be 'predicted' using simple computer software. Widespread use of such software will lead to improved control of shelf-life of perishable products and greater assurance of food safety.

The long term objective was to cover the most important food preservation processes, the common food poisoning organisms, the important food spoilage organisms, and to develop 'user-friendly' models that can be validated by comparison with data from challenge tests by researchers or the food industry.
Improved control of microbial growth and survival are essential if European States are to improve the quality and safety of the food supply with respect to microbial comtamination.
'Predictive Microbiology' is a powerful tool that can underpin improved control in food processing and distribution. Approaches to modelling microbial responses have developed so much that a unified database for the food industries, regulatory authorities and other interested parties is conceivable. This would provide a safer food supply for consumers, and improved control of shelf life and stability of products for consumers, manufactures and distributors.

Predictions of growth responses from the models are very similar to measures of those responses published in the scientific literature, thereby 'validating' the model. Nevertheless, data have been generated on red meats and poulty, fish and fish products, milks and dairy products, beverages, bakery products, vegetables (including ready to use), pasteurized meals and prepared salads. From time to time, testing the modelagainst published growth or death responses identifies a food, or circumstances, where the models are not appropriate. In such cases additional research will be needed.
The relevance of mathematical modelling to food microbiology to improve control of food safety and quality has been demonstrated clearly.

Programmes for modelling on are available for distribution and a PC disc is also available with examples of 2 models developed at the Institute of Food Research (Reading Laboratory United Kingdom) compiled so that the spreadsheet and linked graphics will run with commonly available software such as Excel for Windows, Lotus 1-2-3, Microsoft Works etc. This disc shows the users how simply the models can be used, with only a few minutes of training, and allows the user to compare the growth 'predictions' from the models for salmonellae and the spoilage bacterium Brochothrix thermosphacta with their own experimental results in laboratory media or foods.
There are strong, and increasing, demands from consumers for foods that are more convenient, fresher, more natural, less heavily processed, less heavily preserved (eg containing less salt, less sugar) and less reliant on additives and preservatives. It is essential that the growth and/or survival of microorganisms that can spoil, or limit the shelf life of, these, as well as traditional foods, are controlled. At the same time, there is considerable public concern at the high level of foodborne disease in Europe. That concern includes the morbidity and morality resulting from foodborne illness, and the substantial economic costs involved in its treatment and control.

Improved control of microbial growth and survival are essential if European States are to improve the quality and safety of the food supply with respect to microbial contamination, and to export with confidence, avoiding problems of microbiological hygiene. With the changes in food processing technology, the traditional inspectional approaches to control are proving relatively ineffective. End product testing is costly, slow and, because of the enormous numbers of units produced and the relatively few that can be tested, offers little assurance of safety, taking into account the statistics of sampling and the sporadic occurrence of the microbes of concern. 'Predictive Microbiology' is a powerful tool that can underpin improved control in food processing and distribution. Approaches to modelling microbial responses have developed so much in recent years that a unified database for the food industries, regulatory authorities and other interested parties is conceivable. This would provide a safer food supply f r consumers, and improved control of shelf life/stability of products for consumers, manufactures and distributors.

Coordinator

Institute of Food Research
Address
Reading Laboratory Earley Gate Whiteknights Road
RG6 2EF Reading
United Kingdom