What often causes a rancid flavor in milk?

A rancid flavor in milk is typically caused by the breakdown of fats, which can occur due to extreme agitation of raw milk. When milk is agitated excessively, the mechanical action can break down fat globules and promote oxidation, leading to the development of rancid flavors. This is particularly important in raw milk, where the fatty acids can become more susceptible to air exposure and degradation.

While other factors such as poor storage conditions, contaminated equipment, and excessive pasteurization can affect milk quality and flavor, the primary mechanism behind rancidity is linked to the physical treatment of milk. Extreme agitation not only exposes the milk to oxygen but can also increase the likelihood of enzyme activity that contributes to fat breakdown, making this a significant factor in creating off-flavors in the milk.