HEAT INACTIVATION RATES OF BOTULINUM TOXINS A, B, E AND F IN SOME FOODS AND BUFFERS

Abstract

ABSTRACT Inactivation of botulinum toxins was determined in selected acid and low acid foods and buffer systems. Heating at 74°C and 79°C gave a biphasic curve when the log of the inactivation of the toxins was plotted against the time of heating. At 74°C, the time for inactivation of 10 3 LD 50 of type A toxin per gram of an acid food such as tomato soup to no detectable toxin by mouse assay was an hr. or more. At 85°C the inactivation was very rapid and approached exponential decrease with inactivation to no detectable toxin within 5 min. In general, the toxins were more stable in acid foods such as tomato soup at pH 4.2 than in low acid foods, such as canned corn at pH 6.2. Twenty minutes at 79°C or 5 min at 85°C is recommended as the minimum heat treatment for inactivation of 10 3 LD 50 botulinum toxins per gram of the foods tested.