Comparative Composition of Brandies from Thompson Seedless and Three White-Wine Grape Varieties

Wines prepared from Thompson Seedless grapes and three white-wine grape varieties (French Colombard, Sauvignon blanc, and Peverella) were distilled into brandies in a small copper pot still by the "Charente" method, i.e., by two successive simple distillations. The low wines or first distillates from all four varieties, plus the heads, brandy, tails, and residue fractions obtained by redistillation of the Thompson Seedless and French Colombard low wines, were analyzed comparatively by gas chromatography. Samples of distillates, after adjustment to equal ethyl alcohol strengths, were extracted four times with successive portions of ether-pentane (2:1) and concentrated to small volume for gas-chromatographic analyses on a Carbowax 20M column. Concentrations of 21 minor compounds or congeners were determined by comparing peak areas with that of l-decanol, an internal standard. Relatively small differences in congener levels were found in comparative fractions of the four grape varieties, and the results do not provide a substantive basis for recommending one variety over the others for brandy production. The brandy fractions of French Colombard tended to contain slightly higher levels of the various alcohol and ester congeners and were most often preferred by a small but experienced sensory panel as having a more pleasant and distinct aroma than those of Thompson Seedless. The differences were considered too slight and subtle, however, to be detected with a high level of significance. Most of the alcohols and esters present in distilling wines and in low wines are recovered in the pot-still heads and brandy fractions. The β-phenethyl alcohol, however, is so weakly volatile that it is more abundant in the tails fraction, and, in fact, about one-half remains in the pot liquid residue and so is not recovered.