46G-5 |
Investigations into the mechanism of hemoglobin-mediated lipid oxidation in a washed muscle model system |
R. LI1, I. Undeland2, and M. P. Richards1. (1) Dept. of Food Science, Univ. of Wisconsin, Madison, Meat Science and Muscle Biology Lab., 1805 Linden Dr. W., Madison, WI 53706, (2) Dept. of Food Science, Chalmer Univ. of Technology, PO Box 5401, 29 Goteberg, S-402, Sweden Hemoglobin is a likely catalyst of lipid oxidation in muscle foods which leads to rancidity and off-flavor. It is unclear what could be the regulatory factors in this process. Studies aimed at determining inhibitory or stimulating compounds in hemoglobin mediated lipid oxidation can lead to optimal antioxidant strategies to inhibit lipid oxidation in muscle foods. The objective of these studies was to determine the inhibitory effect of the press juice (PJ) of cod muscle on chicken hemoglobin-mediated lipid oxidation in order to understand the pathway by which hemoglobin stimulates lipid oxidation. Chicken hemoglobin in the ferrous oxidation state was added to washed cod muscle to stimulate lipid oxidation. Thiobarbituric reactive substances (TBARS) and lipid hydroperoxides were determined during 2°ãC storage as indicators of lipid oxidation. PJ of cod muscle was prepared by removal of the supernatant after high speed centrifugation. PJ or cooked (100°ãC, 10 min) and filtered PJ was added to the washed cod containing hemoglobin catalyst. Heat stable protein in PJ was measured by Lowry assay and separated into <10 KDa, 10 KDa~50 KDa and >50 KDa groups by ultrafiltration. Effects of different MW proteins and small MW compounds in PJ were tested in hemoglobin-mediated lipid oxidation system. The PJ strongly inhibited hemoglobin mediated lipid oxidation. 8% of the total protein in PJ remained after cooking and showed comparable antioxidant effects as uncooked PJ. Cooked PJ protein with MW >10 KDa showed a proxidative effect which might be the result of cooking. Low MW components, possiblly proteins, produced the inhibitory effect and overcame the proxidative effect of high MW components in PJ. These results suggest that the inhibitory component in the press juice of cod muscle appears to be heat tolerant, low molecular weight and may be useful to prevent lipid oxidation in muscle foods.
Session 46G, Muscle Foods I
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