LIPID STABILITY OF BEEF MODEL SYSTEMS WITH HEATING AND IRON FRACTIONS

Catalytic effects of different temperatures (55, 70, 85, and 100 degrees C) on lipid oxidation were studied in aqueous- and chloroform/methanol-extracted beef model lipid systems containing iron forms inherent in beef (water-extractable, diffusate, nondiffusate, ferritin, myoglobin, hemoglobin), hematin, FeCl2, or FeCl3. Heating increased thiobarbituric acid and peroxide values in both systems. All forms of iron catalyzed lipid oxidation in aqueous systems, with greatest oxidation by heme and low molecular weight iron fractions. Oxidation in lipid extracts was not increased by ferritin, FeCl2, or FeCl3, but heme iron was the major oxidation catalyst. Lipid stability decreased with addition of any iron forms inherent in beef or with increased heating, which helps understanding of rapid oxidation of meat during refrigerated storage or after cooking.