The effects of prefermentation maceration temperature and percent alcohol (v/v) at press on the concentration of Cabernet Sauvignon grape glycosides and glycoside fractions

Grape-derived aroma and flavor precursors exist partially as nonvolatile, s ugar-bound glycosides. Hydrolysis of these compounds may modify sensory att ributes and potentially enhance wine quality. Prefermentation skin contact at two temperatures and alcohol content at press were monitored to determin e effects on Cabernet Sauvignon glycosides. Total, red-free, and phenol-fre e glycoside concentrations were estimated by the quantification of glycosyl -glucose, After three days, cold soak (10 degrees C) increased total glycos ides by 103%, red-free glycosides by 81%, and phenol-free glycosides by 88% . During the same period, ambient soak (20 degrees C) increased total glyco sides by 177%, red-free glycosides by 144%, and phenol-free glycosides by 1 06%. A reduction in the ratio of red-free glycosides to the total and the r atio of phenol-free glycosides to the total occurred during fermentation. A t fermentation completion, red-free glycosides comprised 30% of the total, and phenol-free glycosides were 23% of the total glycosides. Wines produced by early pressing (10% sugar) had 25% more total and red-free glycosides t han those pressed at dryness.