The several recent outbreaks of botulism, which have been traced to foods preserved by some method of heating, have focused critical attention on the thermal resistance of the spores of Clostridium botulinum. While several papers have been published on this subject, its importance justifies repetition of the work in order that the conclusions based on the data, may be as accurate as possible. The present investigation was initiated before some of the other papers were published and was

more »

... even though the experiments repeated some of those already reported. HISTORICAL Two papers have been published by Weiss (1921a Weiss ( , 1921b which bear directly on the subject under discussion. He reported that the free spores of Clostridium botulinum were destroyed within five hours at 1000C., within forty minutes at 1050C., and within six minutes at 120°C. Weiss believed that the spores were injured before death and that the death process was a gradual one. Such an opinion is in keeping with our knowledge of disinfection by moist heat. Young spores were more resistant than old ones. Those one month old were found to be many times more resistant than older ones. The hydrogen ion concentration was found to have the usual effect. In the second paper Weiss reported some data on the thermal resistance of spores in canned food liquors. The resistance, as would be expected, varied with the reaction of the food. In gooseberry juice the spores were killed in 30 minutes while about 269 on May 10, 2020 by guest