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Inactivating
microbes using high-pressure throttling Source of
Article: http://www.ift.org/news_bin/news/news_home.shtml 8/04/2009-A report
published in the August 2009 issue of Journal of Food Science
explains how researchers at University of Georgia learned to inactivate Clostridium
sporogenes PA 3679 ATCC 7955 in soymilk using continuous flow
high-pressure throttling. During this process, the
temperature of soymilk increased due to instantaneous pressure release and
additional heat was supplied by a heat exchanger to achieve a set
temperature. The soymilk was immediately cooled to less than 40°C after a
short preset hold time. The researchers reported a significant increase in
the heat resistance in C. sporogenes spores when heated in soymilk
compared to 0.1% peptone water. Continuous flow high-pressure throttling
(CFHPT) 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 sec 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. “High hydrostatic pressure
is an effective technique to satisfy consumer demand for fresh-like,
minimally processed shelf-stable product,” said the researchers. “Many other
alternative nonthermal food processing techniques are being studied and used
but among all, the high-pressure processing has been the most promising. CFHPT
system commercially pasteurizes the soymilk in seconds without any viable
microorganisms. Time and temperature are key factors in inactivating
microorganisms even under high pressure.” |
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