Sterol and fatty acid composition of grape seed oils

The content and composition of sterols, sterol esters and fatty acid composition of the triacylglycerol and sterol esters fractions isolated from the seed oil of four Bulgarian grape varieties - Super ran bolgar, Bolgar, Mavroud and Shiroka melnishka loza - were investigated. The total sterol content was estimated to be 0.3-0.4% with an amount of free sterols - 93.4-97.0% and that of sterol esters - 3.0-6.6%. Sterol composition of both sterol fractions was determined by gas chromatography. B-Sitosterol was the main component in both sterol fractions (66.8-73.2%) followed by campesterol (7.1-24.5%) and stigmasterol (2.7-6.9%). The content of cholesterol and stigmasterol in sterol esters was found to be several times higher than in the fraction of free sterols (1.3-2.0% vs 0.5-0.7 % and 3.2-6.9% vs 2.7-3.3% respectively). On the contrary, the percentage of campesterol in the sterol esters (7.1-14.0%) was about two times lower than in the free sterols fraction (19.1-24.5%). Linoleic acid predominated in all samples of sterol esters followed by oleic and palmitic acids (40.7-53.8 %, 24.9-35.5% and 13.0-16.7% respectively); the content of these acids in the triacylglycerols fractions were in the ranges 68.5-72.3%, 16.3-18.7% and 8.8-11.5% respectively.