Evaluation of the safety and prediction of the shelf-life of vacuum cooked foods

The microbial safety and the shelf-life of various vacuum cooked foods were evaluated. In industrial situations the raw material features and size of the products have a wide variability with respect to the rate of thermal increase, pasteurization value and cooling rate. Surviving microorganisms mainly belong to the-genus Bacillus (Bacillus stearothermophilus, B. subtilis, B. pumilus, B. polymyxa, B. sphaericus). Bacillus cereus and Clostridium perfringens were not detected in this study. The shelf-life of the various products, predicted on the basis of a storage test at 4 degrees C, ranged from 40 to 76 days. Thermal abuse at 15 degrees C remarkably decreased the shelf-life and allowed the growth of anaerobic sporeforming bacteria. Challenge testing using a mixture of spores of Bacillus cereus, Bacillus licheniformis and Clostridium perfringens showed that only B. licheniformis was able to survive during storage at temperatures less than or equal to 4 degrees C in all samples. B. cereus proved to have a growth potential only when inoculated in pilaf rice and under abuse conditions, while the viability of C. perfringens continued to decrease during refrigerated storage.