Ultrafiltered Aurore grape juice (pH 3.5, 20° Brix) was inoculated with Saccharomyces cerevisiae and Leuconostoc oenos PSU-1 with and without the addition of insoluble grape solids (13 g/L, dry wt) and/or yeast ghosts (1 g/L). Wine made without insoluble materials (control) attained higher levels of decanoic acid (∼5 mg/ L) during alcoholic fermentation than treatments with insoluble grape solids, (∼1 mg/L), yeast ghosts (∼2.5 mg/ L), or grape solids and yeast solids (∼0.8 mg/L). Alcoholic fermentation stuck and malolactic fermentation (MLF) occurred most rapidly in control wines, while addition of grape solids and/or yeast ghosts stimulated alcoholic fermentation but delayed MLF. These results suggest that inhibition of malolactic bacteria by yeast was probably due to factors other than production of decanoic acid and other medium-chain fatty acids. Presence of insoluble materials during alcoholic fermentation further influenced the formation of higher alcohols and esters and altered the sensory quality of the finished wine.
- Copyright 1990 by the American Society for Enology and Viticulture