A BACTERIOLOGICAL STUDY OF CANNED SALMON

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Abstract
In a 5-year period, 7664 cans of salmon comprising 540 separate lots, 4.6% were found non-sterile and 1.1% were rejected on bacteriological grounds. The 5276 cans classed as normal quality salmon were 3.4% non-sterile, while of the 2398 cans of questionable quality salmon, 7.1% were non-sterile. Bacterial groups isolated from 220 non-sterile cans consisted of sporulating aerobes 81%; cocci 7.3%; non-sporulating rods 7.3%; obligate anaerobes 2.2% and molds 0.4%; 70% of the cans containing aerobes (plate count) showed less than 10 organisms per gm. The most frequently encountered microorganisms were Bacillus mesentericus Flugge, Bacillus vulgatus Flugge, Bacillus subtilis Cohn, Bacillus cereus Frankland, Sarcinae, and Micrococcus various (Dyar). Over 50% of the sporulating aerobes recovered from canned salmon grew on laboratory media and in canned salmon under nearly perfect anaerobic conditions. Likewise many were facultative thermophiles. Cl. botulinum grew vigorously in canned salmon with profuse gas production, putrefaction and liquefaction. No outbreaks of botulism have been attributed to commercially canned salmon. The Salmonella group was not encountered. A bibliography of 27 references is appended.