When spoilage of canned foods occurs what causes the blackening cans?

Blackening of canned foods is typically caused by a bacterial spoilage called sulfidization. This process occurs when sulfur-containing compounds, such as hydrogen sulfide gas, are produced by bacteria inside the can. These compounds react with the metal of the can, causing it to darken and corrode. Sulfidization is most commonly associated with canned foods that contain low levels of acidity, such as corn and green beans.

Improper storage conditions, such as exposure to high temperatures or direct sunlight, can also contribute to the spoilage of canned foods. This can cause the cans to bulge or leak, which can allow bacteria to enter.

To prevent spoilage, canned foods should be stored in a cool, dark place. Once a can is opened, the contents should be consumed within a few days to prevent spoilage.