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Applied and Environmental Microbiology, January 2000, p. 223-229, Vol. 66, No. 1
Faculty of Veterinary Medicine, Department of
Food and Environmental Hygiene, University of Helsinki,
Helsinki,1 and VTT Biotechnology and
Food Research, Espoo,2 Finland
Received 21 June 1999/Accepted 2 November 1999
Sixteen different types of sous vide-processed products were
evaluated for safety with respect to nonproteolytic group II Clostridium botulinum by using challenge tests with low
(2.0-log-CFU/kg) and high (5.3-log-CFU/kg) inocula and two currently
available predictive microbiological models, Food MicroModel (FMM) and
Pathogen Modeling Program (PMP). After thermal processing, the products were stored at 4 and 8°C and examined for the presence of botulinal spores and neurotoxin on the sell-by date and 7 days after the sell-by
date. Most of the thermal processes were found to be inadequate for
eliminating spores, even in low-inoculum samples. Only 2 of the 16 products were found to be negative for botulinal spores and neurotoxin
at both sampling times. Two products at the high inoculum level showed
toxigenesis during storage at 8°C, one of them at the sell-by date.
The predictions generated by both the FMM thermal death model and the
FMM and PMP growth models were found to be inconsistent with the
observed results in a majority of the challenges. The inaccurate
predictions were caused by the limited number and range of the
controlling factors in the models. Based on this study, it was
concluded that the safety of sous vide products needs to be carefully
evaluated product by product. Time-temperature combinations used in
thermal treatments should be reevaluated to increase the efficiency of
processing, and the use of additional antibotulinal hurdles, such as
biopreservatives, should be assessed.
0099-2240/0/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Safety Evaluation of Sous Vide-Processed Products
with Respect to Nonproteolytic Clostridium botulinum by Use
of Challenge Studies and Predictive Microbiological Models
*
Corresponding author. Mailing address: 1409 Millstream
Trail, Lawrenceville, GA 30044. Phone: (678) 380-9923. Fax: (404)
639-3333. E-mail: eih9{at}cdc.gov.
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