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The effects of triglycerides and phospholipids on development of warmed-over flavor (WOF) in cooked meat was studied using model systems from beef and from chicken dark and light meat. Triglycerides, total lipids, total phospholipids, phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) were added back to the lipid extracted muscle fibers in each system and WOF development was followed by the TBA test and taste panel scores after heating to 70°C and holding at 4°C for 48 hr. Total phospholipids, especially PE, were shown to be the major contributors to development of WOF in cooked meat. The triglycerides enhanced development of WOF only when combined with the phospholipids (as total lipids). Phosphatidyl choline (PC) did not influence WOF in the model system. Changes in the PUFAs of the phospholipids were shown to be related to development of WOF in cooked meat. Addition of 156 ppm of nitrite significantly (P < 0.01) reduced TBA numbers and prevented development of WOF.

Acid-heat treatment is not necessary for the condensation of TBA with malonaldehyde nor for maximum colour development. Free malonaldehyde is produced during the oxidative breakdown of unsaturated fatty acids or food products. The amount of free malonaldehyde produced can be measured without acid-heat treatment.The reaction between malonaldehyde and TBA in water or 90% glacial acetic acid has been investigated at different temperatures. The results show that acid-heat treatment of the reaction mixture should be avoided, since the E%Oof the coloured complex is considerably affected by the acid. On the contrary, heating without acid accelerates the condensation of TBA with malonaldehyde without affecting the Ego.

Lipid oxidation is a major cause of deterioration in the quality of meat and meat products. Oxidation can occur in either the stored triglycerides or the tissue phospholipids. Ferric heme pigments have been implicated as the major prooxidants in tissue lipid oxidation. Pigment and lipid oxidation are interrelated, and ferric hemes are believed to promote lipid oxidation. The resulting oxidation destroys the hemes. Nonheme iron and ascorbic acid may also function as prooxidants in meat. Sodium chloride accelerates oxidation of the triglycerides, although the mechanism of salt catalysis is not completely known. Cooked meat undergoes rapid deterioration due to tissue lipid oxidation. The meat pigment in the cured pink ferrous form does not promote the rapid oxidation undergone by cooked uncured meat. Refrigerated and frozen fresh meats are also susceptible to lipid oxidation. Protein denaturation and cross‐linking may result from lipid oxidation in stored freeze‐dried meat. With increased consumption of prepackaged raw meat and precooked convenience meat items, control of oxidation has become increasingly important. Antioxidants and chelating agents are the most effective inhibitors of lipid oxidation.

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