ABSTRACT
Clostridia are present in low numbers in most milk samples. Evidence for common species such as Clostridium perfringens suggest spore levels of less than 1 spore per ml of milk (Jones and Langlois, 1977). Studies by Bergere (1969) with Clostridium tyrobutyricum show that this species is normally present in milk at less than 0.2 spores/ml. Though outbreaks of botulism are not usually associated with dairy products, Clostridium botulinum may enter the milk chain as an environmental contaminant (e.g., in soil, feces, or contaminated ingredient). Information relating to levels of C. botulinum spores in milk is sparse. Studies at the University of Guelph indicate less than 1 C. botulinum spore per liter of raw milk (unpublished data). The low incidence of such spores is confirmed by surveys of dairy products. In a study by Taclindo et al. (1967) with vacuum-packed products such as cheese, the few products examined were negative for spores of C. botulinum. A more extensive study of convenience foods including dairy products was undertaken by Insalata et al. (1969). None of 40 samples of Edam and cheddar or of 10 samples of cheese spreads were found to contain spores of C. botulinum.
