Oxidative Rancidity

Oxidative rancidity is a form of food deterioration in which oxidation of fats produces unwanted odors and flavors. It is especially relevant to fats containing unsaturated fatty acids, which are susceptible to oxidation. This is a chemical change, not microbial spoilage, so rancidity can develop without microorganisms being responsible .^1,2

A common pathway involves a chain of reactions between fatty acids and oxygen. These reactions form lipid hydroperoxides, which are early oxidation products. As hydroperoxides break down, they generate smaller compounds, including aldehydes and ketones, some of which contribute strongly to off-odors and off-flavors .^1,2

Oxidative rancidity refers to the unwanted sensory change, whereas lipid oxidation refers to the underlying chemical reactions. Oxidation products can accumulate before a rancid odor or flavor becomes noticeable .^1,2

The rate and products of oxidation depend on the fatty acids present and on conditions such as oxygen exposure, light, temperature, and other components of the food. These factors help explain why fat-containing foods do not all develop rancid characteristics at the same rate .^1,2