SOY PROTEIN ISOLATE ANTIOXIDANT EFFECT ON LIPID-PEROXIDATION OF GROUND-BEEF AND MICROSOMAL LIPIDS

Soy protein isolate antioxidant (SPIA) was separated from soy protein, fractionated, and purified. SPIA (300 or 900 ppm) was added to a ground beef model system; oxidation was initiated by adding Fe+2/Fe+3. Sealed vials were stored at 4 degrees C for 24 hr. Oxidation products were assessed using the 2-thiobarbituric acid (TBA) test, sensory analysis, gas chromatographic separation, and mass spectrometric identification of headspace volatiles. SPIA (900 ppm) was also added to a beef microsomal protein/linoleic acid model system. Beef containing 900 ppm SPIA had lower TBA numbers, less rancid odor, hexanal, and total volatiles after 16 and 24 hr than did samples containing 300 ppm SPIA and controls.