The influence of water activity on some characteristics of bacterial growth is presented. Bacteria are able to overcome the plasmolytic effect of reduced water activity by intracellularly accumulating compatible solutes such as glutamic acid or proline. In food systems, water activity is one of several preservative factors which interact to form a preservative system. Other preservative factors considered in this review are temperature, pH, O/R potential and chemical preservatives. Control of water activity in foods is receiving more attention as new food products and new technologies are developed.

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Author notes

1Based in part on a seminar presented at the annual meeting of the American Society for Microbiology, March 4, 1981, Dallas, TX.