Clostridium botulinum and Acid Foods 1, 2.

Outbreaks of botulism involving acid foods are rare. Of the 722 total botulism outbreaks reported from 1899 to 1975, only 34 (4.7%) involved acid foods. Home-canned acid foods were implicated in 34 of the 35 acid food outbreaks. Clostridium botulinum cannot grow at a pH of ⩽ 4.6; therefore, for a botulism hazard to exist in an acid food, a contamination with other microorganisms due to a process delivery failure and/or post-process contamination, (c) favorable composition of the food and storage conditions which are particularly conducive to C. botulinum growth and toxin production, and (d) metabiosis. The way each factor affects the botulism hazard in acid foods is discussed in this report. An acid food is safe from C. botulinum if the heat process kills all organisms capable of growth at a pH of ⩽4.6 and there is no post-process contamination.