INVESTIGATION OF THE TRANS 2-HEXENAL CONT ENT IN LEAVES OF GRAPEVINESDURING THE VEGETATION PERIOD

Unsaturated fatty acids in plants are known to be precursors of the bi ologically important group of unsaturated C-6-alcohols and C-6-aldehyd es. These compounds constitute the basis of aroma components called '' green grass flavour''. On the other hand they protect grapevines again st fungal or bacterial infections. Seasonal changes of the content of trans 2-hexenal in leaves of seven varieties of Vitis vinifera were in vestigated from May to August 1994. The highest content of trans 2-hex enal was detected in leaf samples harvested in the last decade of July when clusters started to close (cv. Irsay Oliver 4.1 g/kg dry weight) .