46G-8 |
Partitioning of exogenous d-tocopherol between the triacylglycerol- and membrane lipid fractions of chicken leg muscle |
H. SIGFUSSON, Oklahoma Food & Agricultural Products Research & Technology Center, Oklahoma State Univ., Rm. 106, Stillwater, OK 74078 and H. O. Hultin, Dept. of Food Science, Univ. of Massachusetts, Marine Station, 932 Washington St., Box 7128, Gloucester, MA 01930. Antioxidants are commonly added to ground/minced muscle foods to retard undesirable changes accompanying lipid oxidation. The efficiency of the added antioxidant depends on whether or not it reaches the site where oxidation is initiated and/or propagated. To determine partitioning of vitamin E between triacylglycerol and the less stable membrane lipids of chicken muscle Muscle total lipid content (3-14% w/w) was varied by adding triacylglycerols. Approximately 300ppm d-tocopherol was then added on muscle total lipid basis followed by separation of the lipids by ultracentrifugation. Triacylglycerols were obtained after 30-min centrifugation of minced muscle at 130,000g. Membranes were collected from a muscle-buffer homogenate (pH 7.5) by differential centrifugation. Tocopherol contents of the isolated lipid fractions were determined using HPLC with fluorescence detection after extraction with organic solvents. Experiments were replicated thrice using three total lipid content levels. The triacylglycerols collected represented up to 90% of the total triacylglycerols of the sample. The membranes collected consisted of up to 35% of the total membrane lipids. The partitioning of d-tocopherol between the two lipid fractions depended on the total lipid content. At low total lipid contents (3-5% w/w), the added d-tocopherol was present in approximately the same concentration in both muscle lipid fractions. At higher total lipid contents achieved by adding triacylglycerols, the d-tocopherol concentration in the membranes increased relative to that of the triacylglycerols, becoming up to 2-times higher (p < 0.05) than that of the triacylglycerols. The added tocopherol partitioned between membrane lipids and triacylglycerols in a competitive manner depending on the amount of triacylglycerol present. The results suggest that the partitioning depended on the relative surface areas of the lipids and the affinity of the tocopherol for the different lipids.
Session 46G, Muscle Foods I
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