CATECHINS SPECTROPHOTOMETRICAL DETERMINATION FROM HYDROLYSABLE TANNINS, IN SOME RED GRAPE VARIETIES

Among polyphenols compounds, in grapes and wine are found mostly flavanols, catechins and tannins. They are found in greater quantity in red grapes, compared with the whites. Due to their antioxidant activity, up to 25-100 times more than that of vitamins C and E, was studied their anticancer properties, or cardio and immunoprotector effect.[1] Polyphenols is gathered in the solid parts of grapes (rachis, peels and seeds) and go in must and wine through the process of maceration-fermentation. [2] Catechins content of grape varies with: variety, soil composition, climate, geographic origin, and cultivation practices. This is why we took in study four grape varieties: Cabernet Sauvignon, Merlot, Burgund mare and Muscat Hamburg. The grapes were harvested at complete maturity, from two viticultural areas: West Carpathian Area (Recaş-Timiş) and South Carpathian Area (Merei-Dealu Mare). The fresh grapes were separated in different parts: rachis, grape skins, seeds and must. The solid parts: rachis, peels and seeds were dried at 65°C, made powder and stocked at 25°C. The must was filtrated and preserved in refrigerator at-20°C. The polyphenolic constituents were extracted from the plant material by a series of successive extraction. The extracts obtained were analyzed spectrophotometrically at 510 nm. The method consists of tannins precipitation with bovine seru