Japan Journal of Food Engineering
Online ISSN : 1884-5924
Print ISSN : 1345-7942
ISSN-L : 1345-7942
Recent Developments of Predictive Microbiology Applied to the Quantification of Heat Resistance of Bacterial Spores
Ivan LEGUERINELPierre MAFART
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2008 Volume 9 Issue 1 Pages 1-7

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Abstract

All conventional heat processing calculations are based on as few as two equations: a “primary” equation which corresponds to the first order kinetic of microbial inactivation represented by a log-linear survival curve, and a “secondary” equation which describes the effect of the heating temperature on the thermal resistance of target spores. Improvements of heat inactivation modelling consist in the extension of these equations into more general primary models which are able to fit typical non log-linear survival curves and multifactorial secondary models which take non only heating temperature, but also some new other environmental factors into account. A first models generation inputs only factors such as pH or water activity which are related to the heating phase regardless of recovery conditions. A second models generation further includes environmental factors linked to the recovery conditions of incubation for the calculation of heat resistance. These new trends lead to the main following consequences: i. the efficiency of a heat treatment is more suitably characterised by the bacterial inactivation ratio than by the traditional F-value which is no longer additive, ii. The lethality factor concept can be usefully extended to a more general function which would include not only heating temperature, but also main other environmental factors.

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