2-Thiobarbituric acid-reactive substances (TBARS) values of raw pork, and chicken breast and thigh meats did not change during a 7-d storage period. Low free iron content and high ferric ion reducing capacity (FRC) were responsible for the low TBARS values in those meats during storage. TBARS values of raw beef loin, however, significantly increased during 7-d storage because of high free iron content and high lipoxygenase-like activities by ferrylmyoglobin. The TBARS values of cooked meat increased significantly with storage. Heat-stable FRC was detected in all cooked meat and was responsible for the increase of TBARS in cooked meat during storage. The rate of TBARS increases and the amounts of nonheme iron and heat-stable FRC in cooked beef loin were higher than those in cooked pork loin and chicken breast. In spite of lower amounts of nonheme iron and heat-stable FRC, cooked chicken thigh showed similar levels of TBARS to cooked beef loin after 7-d storage because of its high PUFA content. The total amount of PUFA in meat, most of which were present in triglycerides, influenced the development of lipid peroxidation only in the presence of sufficient amounts of free irons in cooked meat.

This indicated that the content of free ionic iron, myoglobin, and ferric ion reducing capacity (FRC) were the primary determinants for the different susceptibility of raw meats to lipid peroxidation. In cooked meat, the contents of free ionic iron and heat-stable FRC played a key role on the development of lipid peroxidation. PUFA was important for lipid oxidation in cooked meat only when sufficient amount of free iron was present.