1887

Abstract

SUMMARY

Sterilizing doses of -radiation for food products (4·5 Mrad.) do not completely inactivate spore toxin or enzymes. The present study concerns spore toxin during and after irradiation of 4 × 10 spores of per g. of canned ground beef irradiated to 4.5 Mrad., at temperatures of – 25°, 0° and + 25°. During subsequent incubation of irradiated samples at 30° for 10 months, periodic analyses showed no viable spores. Toxin was tested on (i) non-homogenized samples and (ii) samples homogenized in a tissue grinder.

In samples irradiated at – 25° and 0° and in un-irradiated un-incubated controls, 4 minimal lethal doses (m.l.d.) of toxin were found in non-homogenized samples immediately after irradiation. The toxin titre of irradiated samples gradually diminished to approximately half of its initial value at the end of 10 months at 30°. In identical sets of homogenized irradiated samples, 8 m.l.d. were found initially and the titre increased to 44 m.l.d. after 2 weeks to 4 months of incubation at 30°. Thereafter, the toxin titre slowly deteriorated to approximately 25 m.l.d. at the end of 10 months.

Samples irradiated at 25° exhibited a definite increase in toxin titre even immediately after irradiation. This seems to suggest the possibility of new toxin synthesis either during or after radiation. The toxin titre in homogenized samples reached 64 m.l.d. after 2 months at 30° and thereafter slowly diminished to 31 m.l.d. at 10 months.

Toxin titres in radiation-damaged spores were small in comparison to un-irradiated growing in beef which reached 1000 to 5000 m.l.d. in 2 days at 30°.

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/content/journal/micro/10.1099/00221287-56-1-15
1969-04-01
2021-07-31
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