ISSN:
1476-5535
Keywords:
Spore surviors
;
Heat destrictuion
;
Population models
;
Bacillus subtilis
;
Bacillus stearothermophilus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Summary Discrepancies between actual, viable spore populations and those predicted by a classical model during heat sterilization of food and pharmaceutical products have long concerned food engineers and scientists as they pursue new sterilization techniques, including ultra-high temperature processes. Among potential causes of those discrepancies, activation of dormant spores is significant, and models addressing that factor were developed recently. This paper reviews historic and current views on the biology and models of microbial spore populations during heat sterilization. Activation and inactivation of viable spores are emphasized, with each viewed as a first-order reaction. Rate constants of those reactions may differ significantly, inactivation rates of dormant and activated spores may differ, and variations of all rate constants with temperature appear to be well described by Arrhenius equations. Model-based analyses show how categories of survivor response curves observed during isothermal heat treatments can arise from simultaneous activation and inactivation of spores in an overall population. Effects of different distributions of initial subpopulations, different distributions of rate constants, and ‘heat shock’ for homogenizing an indicator population are shown. The complexity of new, multiple process models has not increased greatly, but the potential for accurate, dynamic prediction of product safety after prescribed sterilization has. The relevant biology is understood and accounted for more thoroughly, and it is anticipated that the new models will aid design and evaluation of new and improved sterilization processes for food and pharmaceuticals.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01584193
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