The Effects of Prefermentation Maceration Temperature and Percent Alcohol (v/v) at Press on the Concentration of Cabernet Sauvignon Grape Glycosides and Glycoside Fractions

¹ Department of Food Science and Technology, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061-0418, USA.

bzoeckle{at}vt.edu

Grape-derived aroma and flavor precursors exist partially as nonvolatile, sugar-bound glycosides. Hydrolysis of these compounds may modify sensory attributes and potentially enhance wine quality. Prefermentation skin contact at two temperatures and alcohol content at press were monitored to determine effects on Cabernet Sauvignon glycosides. Total, red-free, and phenol-free glycoside concentrations were estimated by the quantification of glycosyl-glucose. After three days, cold soak (10°C) increased total glycosides by 103%, red-free glycosides by 81%, and phenol-free glycosides by 88%. During the same period, ambient soak (20°C) increased total glycosides by 177%, red-free glycosides by 144%, and phenol-free glycosides by 106%. A reduction in the ratio of red-free glycosides to the total and the ratio of phenol-free glycosides to the total occurred during fermentation. At 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 than those pressed at dryness.

Key words: glycosides, cold soak, alcohol at dejuice, glycosyl-glucose, phenol-free glycosyl-glucose, red-free glycosyl-glucose, G-G

Submitted on February 22, 1999