54F-26 |
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M. ESTRADA-GIRON1, B. G. Swanson2, and G. V. Barbosa-Cánovas1. (1) Dept. of Biological Systems Engineering, Washington State Univ., 213 L.J. Smith Hall, PO Box 646120, Pullman, WA 99164-6120, (2) Dept. of Food Science and Human Nutrition, Washington State Univ., PO Box 646376, Pullman, WA 99164-6376 The present trend toward the application of emerging technologies has produced a number of alternatives other than thermal processing of foods. The use of High Hydrostatic Pressure (HHP) as an alternative process alone, or in combination with thermal treatment is demonstrated to reduce the processing time of foods while minimizing damage to nutritional components and, at the same time, reducing microbial populations. The objective of this research was to investigate the effects of high hydrostatic pressure in the inactivation of Bacillus stearothermophilus spores suspended in soymilk as an aspect related to quality and safety. Inoculated soymilk with an initial count of 1 x 106 CFU/mL was treated at three selected HHP (550, 585, and 620 MPa) and temperatures (70, 80, and 90o C) for 0, 2, 5, 7, 10, 12, and 15 min of holding time. Inactivation of spores occurred for all selected treatments in this study. Highest reduction of spores from initial population was estimated as <102 spores/mL at 620 MPa and 90o C and 7 min of holding time. At the highest level of pressure (620 MPa) an increase in the inactivation rate constant was observed, resulting in a decrease in the D values for all levels of temperature. Smallest D values were calculated as 10.66, 6.18, and 3.51 min at 620 MPa and 70, 80, and 90oC, respectively. The z values decreased with increased pressure treatment with values ranging from 142 to 212 MPa. The values of activation energy required for inactivation of spores at the selected treatments were calculated in the range of 37.57 to 57.44 kJ/mol. In this work, important reduction of these pressure-thermal resistant spores was achieved at selected treatment levels, indicating that HHP may be advantageous in controlling undesirable microorganisms in soymilk.
Session 54F, Nonthermal Processing: General I
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |