Study On The Changing Of Mono-Phenol During Grape Ripening And Wine Aging

In this text, changing of polyphenolic contents during grape ripening and wine aging were studied by high performance liquid chromatography(HPLC). Grape samples of four cultivars (Cabernet Sauvignon(CS), Pinot Noir(PN), Merlot, and Chardonnay(CH)) were collected at Yangling, Shaanxi, in 2005. Four corresponding experimental wines were made from them, and conserved in glass bottles after the end of alcohol fermentation. And the results showed that:1. Method of determining phenolic monomersSix phenolic monomers in grapes and wines including gallic acid, syringic acid, rutin hydrate, 3,4-dihydroxybenzoic acid, (+)-catechin hydrate and ferulic acid were determined simultaneously by HPLC, using Hibar RT Lichrospher C18(250mm×4.0mm, 5μm) column, mobile phase: acetonitrile∶acetic acid∶water =16∶1∶83, flow rate: 1.0mL·min-1, column oven: 30℃, injection volume: 10μL, detection at 280nm.2. Changings of phenolic monomer during grape ripeningDuring grapes ripening, most of polyphenols were (+)-catechin hydrate and gallic acid, and the content of ferulic acid was the least. The contents of gallic acid, ferulic acid and syringic acid in red grapes(CS, PN and Merlot) were more than those in white grape(CH).Changings of main phenolic monomers in grapes were: (1)Changings of gallic acid content in four different grapes were similar: increased first, and then decreased slightly, and in the order: Merlot﹥CS﹥PN﹥CH. (2)The contents of 3,4-dihydroxybenzoic acid in PN, Merlot and CH fell at early days of ripening and then increased to max. before harvesting, and it decreased in the course of CS ripening. (3)The contents of (+)-catechin hydrate in four grapes sharply decreased during grape ripening. (4)With grape ripening, the content of syringic acid in PN and Merlot decreased, but it was contrary in CS. In CH, it was not detected at initial stages of ripening. (5)The contents of rutin in PN, CS and CH decreased gradually and increased first and then decreased in Merlot. At harvesting, it was not detected in CH. (6)The contents of ferulic acid in four grapes were less all the time. It was not detected in CH at early days of ripening and harvesting.3. Changings of phenolic monomer during wine aging...