Phenolic compounds and fatty acids in different parts of Vitis labrusca and V. vinifera grapes

trans-Resveratrol, antioxidant activity, phenolic compounds, proximate composition, and fatty-acid composition were quantified in different parts (peel, pulp, and seeds) of four grape varieties: Brazil (Vitis vinifera), Benitaka (V. vinifera), Isabel (Vitis labrusca) and Niagara (V. labrusca). Large concentrations of polyunsaturated fatty acid (18.84 and 9204.27 mg 100 g− 1), linoleic acid (LA, 18:2n-6), from 5890.87 to 9148.93 mg 100 g− 1, and alpha-linolenic (LNA, 18:3n-3), from 5.25 to 56.85 mg 100 g− 1, were found in different parts of the four grape varieties. The lowest concentrations necessary for 50% inhibition of DPPH were (9.26 to 126.91 μg mL− 1) in seeds; the pulp did not have antioxidant activity. The total phenolic content varied between 0.04 and 122.35 mg EAG g− 1; seeds had the highest concentrations (89.83 to 122.35 mg EAG g− 1), especially in Niagara and Isabel varieties. trans-Resveratrol was detected in peels (1.17 to 12.96 μg g− 1) and seeds (2.03 to 2.44 μg g− 1) of the four varieties; however, it was absent in the pulp.