55-3 |
Hemoglobin-catalyzed oxidation of washed cod muscle phospholipids -effect of added neutral lipids |
I. K. UNDELAND1, M. P. Richards2, and H. O. Hultin1. (1) Dept. of Food Science, Univ. of Massachusetts, Marine Foods Lab., Box 7128, Gloucester, MA 01930, (2) Dept. of Animal Sciences, Univ. of Wisconsin, Madison, Muscle Biology & Meat Science Lab., Madison, WI 53706-1284 Lipid oxidation negatively affects quality of muscle foods during storage. A general opinion is that the susceptibility to oxidation increases with increasing lipid content, i.e., when the neutral lipid to phospholipid ratio is high. Therefore, the food industry sometimes overlook oxidation as a quality problem in lean foods. This apprach can be questioned based on the several reports showing that phospholipids are the prime targets for oxidation initiators. However, it is still unknown if oxidation initiated in the phospholipids can be transferred to the neutral lipid fraction, which would explain if total muscle fat really does affect the oxidation kinetics. The aim of this study was to investigate how added neutral lipids chemically and sensorically affected the progress of hemoglobin-initiated oxidation of phospholipids in washed cod. Ground and washed cod muscle was mixed with 0, 7.5 or 15% menhaden oil . Lipid oxidation was started with 3 microM rainbow trout hemoglobin. The samples were stored on ice for 0 to 9 days and peroxide value (PV), thiobarbituric reactive substances (TBARS) and painty odor was followed. The rate of PV-development ranked the samples as: 0%>7.5%>15% oil. Therefore, initial PV-differences between the samples due to pre-formed hydroperoxides in the oil were rapidly evened out. The TBARS-values and painty odor intensity increased with the same rate in all samples up to day 3, after which the TBARS started to decline. Paintiness did not decline until after 5 days. These data indicate that (i) hemoglobin is as an efficient hydroperoxide decomposer (ii) additions of 7.5% and 15% oil to the washed cod did not affect development of TBARS and painty odor (iii) the target for antioxidative strategies should include the aqueous phase of the muscle to prevent contact between initiators and membranes and to inhibit the breakdown of hydroperoxides.
Session 55, Muscle Foods: Fresh Meat Quality
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