Warmed-over flavor is an unpleasant characteristic usually associated with
meat which has been cooked and then refrigerated. The deterioration of meat flavor is most noticeable upon reheating. As cooking and subsequent refrigeration is the case with most
convenience foods containing meat, it is a significant challenge to the
processed food industry. The flavor is variously described as "rancid," "stale," and like "cardboard," and even compared to "damp dog hair." Warmed-over flavor is caused by the
oxidative decomposition of
lipids (fatty substances) in the meat into chemicals (short-chain
aldehydes or
ketones) which have an unpleasant taste or odor. This decomposition process begins after cooking or processing and is aided by the release of naturally occurring
iron in the meat.