QUANTITATIVE STUDIES ON TERPENES, NORISOPRENOIDES AND THEIR PRECURSORS IN SEVERAL VARIETIES OF GRAPES

Free and glycosylated C-13 norisoprenoids and monoterpenes were extracted from six varieties of Vitis vinifera cv. by selective retention on Amberlite XAD-2. Free compounds were directly analysed by gas chromatography (GC). Glycosides were hydrolysed with glycosidase enzymes and the liberated aglycones were determined by GC. Hydrolysis of the bound fractions by pure glycosidases showed that norisoprenoids were present mainly as arabinosylglucosides and rhamnosylglucosides. Norisoprenoids, monoterpenes and carotenoids in the berries of Alexandria Muscat were determined at 5 stages of the maturation period : during that period carotenoids decreased progressively, with a concomitant increase of the volatile compounds content.