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Food Spoilage by Mesophilic Bacteria

Food Spoilage by Mesophilic Bacteria
Spoilage of canned foods by mesophilic organisms is indicative of under processing and is caused by species of Bacillus, Clostridium, yeast and fungi.

Clostridium butyricum and C. pasteurianum produce a butyric acid type of fermentation in acid or medium acid foods with swelling of the container by the production of Co2 and H2, Other species of clostridia may produce H2S and other malodorous compounds causing the can to swell.

These putrefactive an­aerobes generally grow in low acid foods such as peas, corn, meat, poultry etc., but sometimes may also spoil medium acid foods. Some bacilli such as B. subtilis and B. mesentroides have been found to grow in poorly evacuated cans of sea food, meat and milk.

The gas forming bacilli (B. polymyxa, B. macerans) are also reported to cause spoilage of canned peas, spinach, peaches and tomato. The presence of nonspore forming bacteria in canned food is also indicative of a leak or under processing. Organisms which are thermoduric include enterococci, Streptococcus thermophilus etc.

These heterofermentatives produce CO2 and swell, the can. Some other non-gas forming, non-spore forming bacteria causing spoilage in cans are species of Pseudomonas, Micrococcus, and Proteus.

Molds, yeasts and their spores are destroyed at the pasteurization, temperature. Their presence in canned food is the result of either gross under processing or leakage. Spoilage of canned fruits and fruit products or milk by yeasts may result in CO2 production and swelling of the cans. Film yeasts and fungi grow on the surface and cause degradation of the products summarizes the types of, spoilage commonly encountered in canned foods.

 

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