Yilmaz Yusuf, Toledo Romeo T
Department of Food Science and Technology, The University of Georgia, Athens, Georgia 30602-7610, USA.
J Agric Food Chem. 2004 Jan 28;52(2):255-60. doi: 10.1021/jf030117h.
Grape seeds and skins are good sources of phytochemicals such as gallic acid, catechin, and epicatechin and are suitable raw materials for the production of antioxidative dietary supplements. The differences in levels of the major monomeric flavanols and phenolic acids in seeds and skins from grapes of Vitis vinifera varieties Merlot and Chardonnay and in seeds from grapes of Vitis rotundifolia variety Muscadine were determined, and the antioxidant activities of these components were assessed. The contribution of the major monomeric flavonols and phenolic acid to the total antioxidant capacity of grape seeds and skins was also determined. Gallic acid, monomeric catechin, and epicatechin concentrations were 99, 12, and 96 mg/100 g of dry matter (dm) in Muscadine seeds, 15, 358, and 421 mg/100 g of dm in Chardonnay seeds, and 10, 127, and 115 mg/100 g of dm in Merlot seeds, respectively. Concentrations of these three compounds were lower in winery byproduct grape skins than in seeds. These three major phenolic constituents of grape seeds contributed <26% to the antioxidant capacity measured as ORAC on the basis of the corrected concentrations of gallic acid, catechin, and epicatechin in grape byproducts. Peroxyl radical scavenging activities of phenolics present in grape seeds or skins in decreasing order were resveratrol > catechin > epicatechin = gallocatechin > gallic acid = ellagic acid. The results indicated that dimeric, trimeric, oligomeric, or polymeric procyanidins account for most of the superior antioxidant capacity of grape seeds.
葡萄籽和葡萄皮是诸如没食子酸、儿茶素和表儿茶素等植物化学物质的良好来源，是生产抗氧化膳食补充剂的合适原料。测定了酿酒葡萄品种梅洛和霞多丽的葡萄籽和葡萄皮以及圆叶葡萄品种麝香葡萄的葡萄籽中主要单体黄烷醇和酚酸的含量差异，并评估了这些成分的抗氧化活性。还测定了主要单体黄酮醇和酚酸对葡萄籽和葡萄皮总抗氧化能力的贡献。没食子酸、单体儿茶素和表儿茶素的浓度在麝香葡萄种子中分别为99、12和96毫克/100克干物质（dm），在霞多丽种子中为15、358和421毫克/100克dm，在梅洛种子中为10、127和115毫克/100克dm。这三种化合物在酿酒厂副产物葡萄皮中的浓度低于种子中的浓度。根据葡萄副产物中没食子酸、儿茶素和表儿茶素的校正浓度，葡萄籽中的这三种主要酚类成分对以氧自由基吸收能力（ORAC）衡量的抗氧化能力的贡献小于26%。葡萄籽或葡萄皮中酚类物质的过氧自由基清除活性从高到低依次为白藜芦醇＞儿茶素＞表儿茶素 = 没食子儿茶素＞没食子酸 = 鞣花酸。结果表明，二聚体、三聚体、寡聚体或多聚体原花青素是葡萄籽卓越抗氧化能力的主要成分。
