Microbiology of Food

Microbiology of Food

Food Spoilage by Thermophilic Bacteria - Under processing of canned foods results in spoilage by thermophilic bacteria and the three types of spoilage by thermophiles are: (i) flat sour, W) thermophilic acid (T A) spoilage, and (iii) sulphide spoilage. In flat sour, the ends of the can remain flat and spoilage cannot be detected unless the can is opened.

The spoilage occurs in low acid foods and is caused by thermophilic species of Bacillus; such as B. coagulans and B. sterothermophilus. These organisms produce acid without gas. In TA spoilage, the can swells due to production of CO₂ and H₂ by Clostridium thermosaccharolyticum. Spoilage mostly occurs in low and medium acid foods. C. thermos accharolyticum is an obligate thermophile and therefore needs hot storage for its development.

Sulphide spoilage (sulphur stinker) is caused by Clostridium nigrificans in low acid foods. Spores of this bacterium are not very heat resistant and their appearance is an indication of under processing. Spoilage is indicated by the presence of H₂and blakening of the material. Sources of all these organisms are generally, the plant equipment, sugar, starch, and other material or soil.

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