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

Free volatiles, and those hydrolytically released from glycosidic form s, were analyzed for Sauvignon Blanc juices from three successive vint ages. Most of the 213 compounds identified were in one of the biogenet ic categories: norisoprenoids, benzene derivatives, monoterpenes or al iphatics. Several have not been previously reported as grape component s. Monoterpenes were in lower concentration than normally found in flo ral grape varieties, but at higher levels than reported in Chardonnay juices. A notable proportion (40-50%) of the bound monoterpenes were m onocyclic. Hydration of alpha-terpineol at pH 3 gave 1-hydroxy-1-methy lethyl)-1-methyl-r-1-cyclohexanol (cis-p-menthane-1,8-diol) and (1-hyd roxy-1-methylethyl)-1-methyl-r1-cyclohexanol (trans-p-menthane-l,8-dio l) as the main products and a low yield of t-4-(1-methylethyl)-r-1-met hylcyclohexane-1,4-diol (trans-p-menthane-1,4-diol) . These were confi rmed as major components of the acid hydrolysates of the bound fractio n.