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Rapid prediction of microbiological shelf life Over the past ten years, CCFRA has led the field in modelling the growth of spoilage organisms as a tool to help companies determine the shelf-life of food products. Models have been produced for major groups of spoilage organisms such as Pseudomonas, Enterobacteriaceae, Bacillus and yeasts and for spoilage consortia of relevance to different food commodities. Many models for spoilage organisms do not allow the inclusion of the effects of extrinsic factors such as modified atmosphere packaging within the model.Work is on-going to assess the validity of the current model for Enterobacteriaceae developed under different conditions of temperature, pH and water activity for use under modified atmosphere conditions. In addition, data has been gathered on microbial spoilage of fresh produce under different packaging conditions and new models will be developed in early 2006. A new approach to modelling microbiological data has also been developed. Traditional models are fitted to data in two stages: a primary stage which fits a single growth curve to each data set, and a secondary stage which looks at the effects of temperature, pH etc on the shapes of the growth curves. CCFRA has developed a model which combines these two stages into one.This is a more powerful use of the data and will allow us to produce models over a wider matrix of conditions and including more factors of importance to food stability. The new system can also be used to fit data on microbial death rates, so models for the effect of pasteurisation processes on spoilage organisms under a range of environmental conditions could also be developed. There are very few models of this type available for the food industry and it is an area which is of considerable importance, allowing pasteurisation treatments to be designed and refined with ease. Contact: Gail Betts |