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Microbial Inactivation Kinetics in Soymilk during Continuous Flow High‐Pressure Throttling
Author(s) -
Sharma Vijendra,
Singh Rakesh K.,
Toledo Romeo T.
Publication year - 2009
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2009.01201.x
Subject(s) - clostridium sporogenes , chemistry , bandwidth throttling , spore , food science , hydrostatic pressure , high pressure , d value , chromatography , clostridium , microbiology and biotechnology , bacteria , biology , thermodynamics , genetics , physics , gas compressor
The thermal resistance of Clostridium sporogenes PA 3679 ATCC 7955 was determined in soymilk (pH 7) and 0.1% peptone water (pH 7) by the capillary tube method. In the continuous flow high‐pressure throttling, the temperature of soymilk increased due to instantaneous pressure release and the additional heat was supplied by a heat exchanger to achieve the set temperature. The soymilk was immediately cooled after a short preset hold time to below 40 °C. A significant increase in the heat resistance was observed in C. sporogenes spores when heated in soymilk in comparison to 0.1% peptone water. The D 121 ‐value for spores in soymilk was approximately 3‐folds higher than peptone water. The z‐ value was also much higher in soymilk as compared to that in 0.1% peptone water. Continuous flow high‐pressure throttling (HPT) from 207 or 276 MPa to atmospheric pressure reduced the microbial populations in inoculated soymilk up to 6 log cycles when the holding times were 10.4, 15.6, and 20.8 s and the process temperatures were 85, 121, 133, and 145 °C, respectively. The sporicidal effect increased as the operating pressure, time, and temperature were increased. More injured spores were found at 207 MPa than at 276 MPa, indicating that lower pressure caused cell injury whereas high pressure caused cell death.