Volatile Aroma Constituents of Vitis Rotundifolia Grapes

Abstract

1. The volatile essence compounds from mixed varieties of Vitis rotundifolia have been determined to include ethyl alcohol, n-butyl alcohol, n-hexyl alcohol, β-phenylethyl alcohol, an acetate ester, a laurate ester, and an isopropyl ester. Methyl alcohol, n-hexanal, 2-hexenal, and acetal also are probably present. 2. The volatilte essence from the crop of a later year from the same vines was isolated by a technique which included the aroma material produced by fermentation of the grapes. This essence was found to contain methyl alcohol, isoamyl alcohol, acetaldehyde, biacetyl, n-hexanal, 2-hexenal, isobutyraldehyde, ethyl acetate, a caproate ester, a caprylate ester, and a caprate ester in addition to the compounds found definitely present in the unfermented essence. Methyl-ethyl ketone and acetal were also probably present. 3. A reduced pressure pot distilling volatile essence isolation technique is compared with a flash evaporation technique and it is demonstrated that the latter technique isolates an essence which is probably most nearly representative of that which actually exists in the intact grape. 4. <b>Vitis rotundifolia</b> volatile essence is shown to be free of nitrogen and sulfur containing compounds, thus providing a possible means of differentiation from labrusca varieties which contain anthranilic acid esters.