Flat sour
It is a physical phenomenon that because in case of cleaning off the raw material was not enough, Spore-forming bacteria consists of heat resistance and anaerobic effects that would still remain when the spore-forming bacteria are bred that would produce lactic acid after food was canned. And because of this lactic acid, it may turn sour food slightly. However, because it is lactic acid, even if you eat, it won’t affect human body.