Causes and Prevention of Warmed-Over Flavor

Oxidative rancidity is a major cause of flavor deterioration in thermally treated meats. Common methods of preserving food quality, such as refrigeration, do not prevent lipid oxidation and the reaction even takes place at freezing temperatures. Off-flavors due to oxidative changes in meat are autocatalytic type reactions which produce various by-products that contribute to the rancid odors and flavors. The rapid expansion of the meat processing industry in the area of precooked ready-to-eat meats has challenged the meat scientist to find methods of controlling rancidity. Growing demands of consumers for quick food service in the form of meats served through food production franchises or frozen entrees has prompted renewed interest in preventing oxidized flavor. Several descriptive terms, such as "stale," or "rancid," have been used to characterize the oxidized flavor which develops in meats following thermal treatment, but perhaps the term "warmed-over" is one which most consumers have recognized in reheated leftover meats. The term was used by Tims and Watts (1958) to describe the rapid development of lipid oxidation in refrigerated cooked meats.