Safety evaluation of sons vide-processed products with respect to nonproteolytic Clostridium botulinum by use of challenge studies and predictive microbiological models

Sixteen different types of sous vide-processed products were evaluated for safety with respect to nonproteolytic group IT Clostridium botulinum by usi ng challenge tests with low (2.0-log-CFU/kg) and high (5.3-log-CFU/kg) inoc ula and two currently available predictive microbiological models, Food Mic roModel (FMM) and Pathogen Modeling Program (PMP). After thermal processing , the products were stored at 4 and 8 degrees C and examined for the presen ce 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 pro ducts 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 degrees C, one of them at the sell-by date. The predic tions generated by both the FMM thermal death model and the FMM and PMP gro wth models were found to be inconsistent with the observed results in a maj ority of the challenges. The inaccurate predictions were caused by the limi ted number and range of the controlling factors in the models. Based on thi s 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 biopre servatives, should be assessed.