FREE AND BOUND VOLATILE SECONDARY METABOLITES OF VITIS-VINIFERA GRAPE CV SAUVIGNON-BLANC

Free volatiles, and those hydrolytically released from glycosidic forms, were analyzed for Sauvignon Blanc juices from three successive vintages. Most of the 213 compounds identified were in one of the biogenetic categories: norisoprenoids, benzene derivatives, monoterpenes or aliphatics. Several have not been previously reported as grape components. Monoterpenes were in lower concentration than normally found in floral grape varieties, but at higher levels than reported in Chardonnay juices. A notable proportion (40-50%) of the bound monoterpenes were monocyclic. Hydration of alpha-terpineol at pH 3 gave c-4-(1-hydroxy-1-methylethyl)-1-methyl-r-1-cyclohexanol (cis-p-menthane-1,8-diol) and t-4-(1-hydroxy-1-methylethyl)-1-methyl-r1-cyclohexanol (trans-p-menthane-l,8-diol) as the main products and a low yield of t-4-(1-methylethyl)-r-1-methylcyclohexane-1,4-diol (trans-p-menthane-1,4-diol) . These were confirmed as major components of the acid hydrolysates of the bound fraction.