Unravelling the mode-of-action of preservation processes through functional genomics on survivors
S. BRUL, Dept. of Food Processing, Amsterdam Univ./Unilever Research, Olivier van Noortlaan 120, Vlaardingen, 3133 AT, Netherlands, F. M. Klis, Swammerdam Institute for Life Sciences, Amsterdam Univ., Kruislaan 318, Amsterdam, 1098 SM, Netherlands, and P. Coote, Centre for Biomolecular Sciences, Univ. of St. Andrews, North Haugh, Saint Andrews, Fife, KY169ST, United Kingdom.
Heat sterilisation and chemical additives are frequently used in processes of the food industry aimed at preserving industrial food products. Although effective, they may seriously affect nutritional value and flavour. In addition, there is a strong tendency in food legislation to lower the permitted levels of chemical preservatives in food products. This has led to a search for new and milder preservation strategies including the use of mild-heat processes combined with natural antimicrobial molecules and or an alternative to heat processing such as the application of high hydrostatic pressure. In all cases it is crucial that resistance development is avoided from the beginning. This presentation will show how modern tools in biology such as genomics, protein expression data and metabolic pattern recognition can aid in understanding the mode-of-action of preservation processes. We will discuss extensively two main cases in the model microorganism Saccharomyces cerervisiae (bakers yeast) i.e. the application of mild-heat processes and the addition of preserving compounds including sorbic acid. Additionally, we will include the latest molecular information with respect to mode-of-action and resistance towards high hydrostatic pressure. The data discussed is analysed with a mixture of novel molecular biological tools and bioinformatics including advanced pattern recognition software packages. This allows us to (i) characterize and classify the stress and adaptation/ salvage responses in S. cerevisiae; (ii) identify characteristic RNA expression profiles ('signatures'); (iii) to identify combinations of preservation treatments with a strong synergistic effect. These data will be put in a broader context including application on filamentous spoilage fungi such as Aspergillus niger and spoilage bacteria such as spore forming species from the genera Bacillus. The outlook will indicate how the information can be used to construct predictive models to answer the question which combinations of antimicrobial preservation processes will be most effective in specific food products.
Session 6, Effect of combinations of thermal and nonthermal treatments on microbial survival