The study reported here was undertaken to investigate a phenomenon reported t o this laboratory by a canner who regularly checked his nonacid vegetable packs for thermophilic spores by incubating samples immediately after processing. Lots of canned peas which showed flat sours in samples incubated a t 131°F. (55°C.) when packed, failed to develop any spoilage when tested several months later prior to shipping. Because of the general high resistance of thermophilic spores to destruction by heat, it had not previously been suspected that they might die out during relatively short periods of holding under conditions unfavorable for germination.A preliminary, inoculated experimental pack of cream style corn was made in 1944, and the results are included here as a matter of interest. Curran and Evans (I), who later made a similar study which included milk and other nutrient and non-nutrient substrates, have referred to this unpublished data in their paper. An experiment with more variables was undertaken the following year, but the samples were destroyed by a laboratory fire. There has now been opportunity to complete work covering several strains of thermophilic bacteria processed at varying levels of sterilizing value in substrates of peas, corn, and dog food.The term "autosterilization" has frequently been applied to the condition existing in spoiled food where no viable organisms can be recovered by cultural methods, and self-destruction of the spoilage organisms by their own metabolic products is assumed. It is used here in a somewhat different sense to describe the dying out, or loss of viability, of spoilage spores which have never grown in the product.
EXPERIMENTALThe general plan of the experiments consisted of preparing inoculated packs in enamel-lined thermal death time cans (205X006) for storage, followed by incubation of portions of the samples a t selected intervals. The products were packed in the cans using a 13-g. fill, 0.
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