Fatty acid composition and phenolic antioxidants of winemaking pomace powder

The fatty acid composition, phenolic constituents and contents, and antioxidant activities of two varieties (‘Cabernet Sauvignon’ and ‘Royal Rouge’) of grape pomace powder from the winemaking industry were examined. Large proportions of polysaturated fatty acids (PUFA), ranging from 60.9% to 64.4%, high ratios of PUFA/SFA, ranging from 2.80 to 3.11, and high ratios of n−6/n−3, ranging from 20.8 to 36.9, were found in both varieties. Five classes of lipids were separated with thin-layer chromatography and identified as polar lipids (PL), sterols (ST), free fatty acids (FFA), triglycerides (TG) and cholesteryl esters (CE). TG showed the highest PUFA contents (64.4% and 66.2%) and n−6/n−3 ratios (70.7 and 55.1), while CE showed the lowest values of PUFA (33.2% and 26.5%). High contents of phenolics and anthocyanins, which contribute to considerably strong antioxidant activity, were found in both varieties. Grape pomace contains considerably high amounts of phenolics, a large proportion of which are anthocyanin pigments (52% of ‘Cabernet Sauvignon’ and 63% of ‘Royal Rouge’). The HPLC analysis of phenolic compounds showed that catechin, epicatechin, epicatechin gallate, and gallic acid were major constituents. Antioxidant properties of grape pomace extract significantly varied with variety and appeared to be dependent upon the contents of phenolics. In addition, from the point of nutrition, “Royal Rouge’ had better benefits because of its lower n−6/n−3 ratio, higher contents of phenolic antioxidants and anthocyanin, and higher antioxidant activity than ‘Cabernet Sauvignon’.