15D-19 |
Effect of high pressure combined with heat on reducing populations of Alicyclobacillus acidoterrestris in apple juice |
S. Y. Lee, R. H. Dougherty, and D. H. KANG. Department of Food Science and Human Nutrition, Washington State University, Pullman, WA 99164-6376, Pullman, WA 99164-6376 Alicyclobacillus acidoterrestris, a thermoacidophilic and spore-forming bacterium, has been identified as a spoilage organism in commercially pasteurized fruit juices. A. acidoterrestris spores, besides being resistant to the pasteurization treatments normally applied to acidic fruit juice products, can germinate and grow under storage conditions. Therefore, this microorganism was suggested as an indicator organism to test the adequacy of pasteurization protocols. The objective of this study was to investigate the effectiveness of combined high pressure and heat treatment in reducing populations of A. acidoterrestris spores in commercially pasteurized apple juice. In this study, each of three high pressure treatments (207, 414, and 621 MPa) was performed at each of four different temperatures (22, 45, 71, and 90°C) in a menstruum of commercial apple juice. Treatment with high pressure alone at 22°C did not reduce the numbers of spores. Nor did high temperature treatment alone reduce A. acidoterrestris spores. However, the combination of high pressure and heat strongly reduced the numbers of A. acidoterrestris spores. When spores were treated with high pressure at 45 or 71°C, there was significant reduction. Treatment at 414 or 621 MPa at 71°C for 5 min, and at 90°C for 1 min reduced spores to undetectable levels (<1 CFU/ml). From these results, it is obvious that the combination of high pressure and heat can strongly reduce the populations of A. acidoterrestris in apple juice. This information would be highly useful to fruit juice processors.
Session 15D, Food Microbiology: Fruits and vegetables
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