However, except for the single raw potato sample and one other
samplewith uncertain origin of the potato ingredient (product category
G inTable 1) all other samples that tested positive for B. cytotoxicus were
dehydrated pre-products or products made thereof (categories A to G,
preformed chips from category H, instant soups from category J).
This suggests a possible selective advantage for thermotolerant
B. cytotoxicus during the industrial production of dehydrated potato
products that often involves moderate heating steps (cf. Belitz et al.,
2001). In how far B. cytotoxicus is more resistant to these heating steps
than other Bacilli, as suggested by Guinebretiére et al. (2008), or if
other factors like anti-browning agents and additives play a role in the
apparent selection during the production process of dehydrated products
will have to be subject to further study.
Based on our own previous findings, this study focused on the investigation
of potatoes and potato products for the presence of B. cytotoxicus.
In how far other foods, especially those that are heat-treated during their
industrial processing, are a common source of B. cytotoxicus, will have to
be investigated in further studies.
References
Anonymous, 2004. ISO 7932:2004: Microbiology of Food and Animal Feeding Stuffs —