noun.
The quality of being rancid; a rankly sour or tainted smell and taste, as of old oil.
noun.
The chief cause of rancidity in fats is hydrolysis of the glycerides, the elements of water being taken up and the free fatty acids and glycerin being formed. The favoring conditions of the change are the presence of moisture and atmospheric oxygen, exposure to light, and contact with albuminoid and mucilaginous impurities.