EFFECT OF HIGH HYDROSTATIC PRESSURE ON SPORES OF GEOBACILLUS STEAROTHERMOPHILUS SUSPENDED IN SOYMILK |
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| Authors: | YOKIUSHIRDHILGILMARA ESTRADA-GIRÓN JOSÉ A GUERRERO-BELTRÁN BARRY G SWANSON GUSTAVO V BARBOSA-CÁNOVAS |
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| Affiliation: | Biological Systems Engineering Department L.J. Smith Hall Room 213 Washington State University Pullman, WA 99164-6120; Food Science and Human Nutrition Department Washington State University Pullman, WA; Depto. Ing. Química y Alimentos Universidad de las Américas, Puebla Sta. Catarina, Cholula, Puebla, México |
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| Abstract: | The inactivation of Geobacillus stearothermophilus spores (ATCC 7953) inoculated in soymilk was investigated using high hydrostatic pressure (550, 585 and 620 MPa) in combination with temperature (70, 80 and 90C) for selected times (2 s to 15 min). Inactivation of spores occurred at all selected treatments. Less than 10 CFU/mL of G. stearothermophilus were observed after 7 min of treatment at 620 MPa and 90C. An increase in the inactivation rate constant, at the highest pressure, was observed, resulting in a decrease in D values at all temperatures. D values were calculated as 10.6, 6.2 and 3.5 min for 70, 80 and 90C, respectively after pressurization at 620 MPa. zp values decreased as temperature increased with values ranging from 142 to 238 MPa. The activation energy required for inactivation of G. stearothermophilus spores in soymilk, at the selected treatments, was in the range of 37.9–57.4 kJ/mol. |
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