Origin of flat sour
Examples from the Web for flat sour
Flat-sour often causes annoyance to beginners in canning some vegetables, such as corn, peas, beans and asparagus.
However, the taste and odor are so disagreeable you will have no desire to eat "flat-sour" canned goods.
This "flat-sour" is not harmful and must not be confused with "botulinus," which is harmful.