How does hydrolysis contribute to rancidity in butter?

In the context of fat and oil processing, hydrolysis contributes to the rancidity of butter by breaking down the glycerides present in the milk fat.

This chemical process liberates free fatty acids from the fat molecules. In butter, this specifically releases short-chain carboxylic acids, most notably butyric acid. Because these liberated acids are volatile and possess strong, malodorous properties, their accumulation results in the characteristic unpleasant odor and flavor associated with rancidity.12