Effect of Salt Content and pH on Toxigenesis by Clostridium botulinum in Caviar

Bottled lumpfish caviar was prepared with different salt (NaCl) concentrations and pH, and injected with spores of Clostridium botulinum . Under abusive storage conditions (30 C), outgrowth and toxigenesis occurred at combinations of ≤ 3.95% salt in the water phase and pH ≥ 5.2, and of ≤ 4.67% salt and pH ≥ 5.6. No toxin was formed at salt concentrations of ≥ 5.56% or at pH ≤ 5.0. A survey of commercial caviar products showed that most of these had salt-pH combinations which would effectively inhibit C. botulinum at abusive temperatures during storage.