Isoamyl Acetate — a Key Fermentation Volatile of Wines of Vitis Vinifera CV Pinotage

¹ Department of Oenology, University of Stellenbosch, Stellenbosch 7600, South Africa.

Young red table wines of the cultivar Pinotage (Vitis vinifera: Pinot noir x Cinsaut) have a distinctive fermentation bouquet. This bouquet is not present in either the Pinotage grapes or must but is known to be formed during fermentation. Isoamyl acetate, when present in relatively large concentrations, was shown to be the "impact" compound responsible for this typical bouquet. Wines from other cultivars to which isoamyl acetate had been added were classified as being typically Pinotage in the course of a red varietal wine evaluation. Examination of the results from two of the 1975 Wine Shows indicated that the presence of this bouquet is evidently considered to be a positive quality-enhancing factor. During aging this bouquet gradually decreased in intensity and finally disappeared. This change was accompanied by a concurrent decrease in isoamyl acetate concentration. A similar reduction in bouquet intensity and isoamyl acetate concentration was observed when the wine was exposed to an excess of oxygen, as well as elevated temperatures.