Mesophilic
Clostridial and
Bacillial spores in raw meat obtained from canning plants were quantified. Most of the samples were imported from foreign countries, and some of them were frozen and the others were defrozen to use in manufacture.
Two procedures, the anaerobic pouch method using Modified Angelotti agar (MAA, Bladel, 1965) and the tube method to obtain most probable number using differential reinforced clostridium medium (DRCM, Gibbs and Freams, 1965), were employed for differential count of
Clostridial spores. The samples indicated very small
Clostridial count, and none of
Clostridial spore could be detected in more than a half of samples investigated. The low level of
Clostridial spores was maintained during and after the defreezing process.
The incidences of
Bacillial spores in the samples were different between frozen and defrozen meat, and the level of defrozen meat showed ten-fold count of frozen meat. The mean levels of
Bacillial spores were 10 to 100/g for frozen meat and 100 to 1000/g for defrozen meat.
The reliability concerning with the respective differential reactions, blackening or non-blackening, of the medium employed was discussed by generic discrimination of organisms isolated from the colonies or the tubes those had shown the respective differential characteristics.
Clostridia occupied in the colonies or the tubes, those had shown blackening or non-blackening, were 65 and 37% in MAA, and 65 and 16% in DRCM, respectively.
None of toxigenic
Clostridia was detected in the samples.
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