How can it be prevented? Flat sour is usually caused by canning overripe food or allowing precooked foods to stand in jars too long before processing or slow cooling of jars after processing. It may be prevented by using fresh products and properly processing, cooking and storing.”

What causes flat sour spoilage?

Flat-sour spoilage occurs in low-acid and acid canned foods. Flat-sour spoilage in acid canned foods is also caused by Bacillus thermoacidurans. The sources of flat-sour spoilage bacteria are usually plant equipment, sugar, starch, and soil.

What is flat sour when canning?

: fermentation of canned products (as peas or corn) that is caused by thermoduric microorganisms which survive the canning process and that is characterized by the formation of acid without gas sometimes : the off-flavor produced by such fermentation.