Microbial Spoilage of Canned Food

Microbial spoilage of canned food occurs when heat processing fails to meet standard requirements. This can occur because of home canning of foods or carelessness in handling the raw materials before canning which results in a high level of contamination that ordinary heat processing may not control. Spoilage can also occur when defective containers permit the entrance of microorganisms after the heat process. Bacteria can cause heat resistant endospores which results in the spoilage of commercially canned foods. The processing of low-acid foods is over particular concern because Clostridium botulinum thrives in this environment and causes botulism food poisoning. There are three types of spoilage: flat sour, T.A., and stinker spoilage. Flat sour pertains to spoilage in which acids are formed with no gas production. T.A. spoilage is caused by thermophilic anaerobes that produce acid and gases in low-acid goods. Cans swell and sometimes burst. Stinker spoilage is due to spore formers that produce hydrogen sulfide and blackening of the can.