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Heat‐Activation Kinetics of Endospores of Bacillus subtilis a
Author(s) -
BUSTA F. F.,
ORDAL Z. JOHN
Publication year - 1964
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.1365-2621.1964.tb01742.x
Subject(s) - bacillus subtilis , endospore , incubation , spore , kinetics , chemistry , bacillales , biology , microbiology and biotechnology , biochemistry , bacteria , physics , genetics , quantum mechanics
SUMMARY Bacillus subtilis strain 5230 endospores suspended in water at a concentration of ca. 1 × 10 8 spores per ml were heat‐activated at eight temperatures ranging from 5 to 94°C. The response was measured by plate count and recorded as the beat‐activated decimal fraction of the total viable count. The method for determining total viable count ineluded a medium containing CaCl 2 and Na 2 dipicolinate. This medium enumerated total viable populations, which were equivalent to total direct microscopic counts, without the usual beat‐treatment requirement. A method was developed to evaluate the contribution by the plate‐count incubation to the total heat treatment. The exposure times were corrected to compensate for the incubation heat treatment. The heat‐activation response was obtained throughout the entire range of test temperatures; however, the exposure time required to achieve the response was extended as temperature was decreased. The logarithm of the rate of heat activation was related to the test temperature, i.e., at a lower temperature, a longer time was required for the response. The thermo‐dynamic properties for the system were: ΔH‡= 27.9 keal; ΔF‡= 25.1–26.4 kcal; ΔS‡= 4.6–8.1 cal/deg.