Raleigh Strott* and Kelly Johnson
*FLCC, 100 Empire Dr, Geneva, NY, 14456 (rstrott@fingerlakes.edu)

Native fermentation is a process that uses ambient, indigenous yeast from the vineyard as the inoculate for wine fermentation, as opposed to commercially produced dry cultures. In this experiment, these two methods of inoculation are compared. Microbial populations in each replicate were monitored by PCR analysis. Flavor was analyzed by monoterpene analysis and sensory difference testing by triangle test. It is hypothesized that these native yeast constituents will produce a wine with discernably different organoleptic complexity than commercially available yeasts. Native yeasts are found in different concentrations by grape variety, with uninoculated, native fermentations having the greatest diversity. Some rare species of yeast can be found on non-vinifera grape varieties. These microbial communities in each vineyard regulate grapevine health and the character of the resulting wine. A variety of native yeasts have been isolated that demonstrated fermentation abilities like glucose and ethanol tolerance equal to or greater than commercial control yeasts. Evidence was found that indigenous yeasts are more apt to create wines with preferred characteristics than their commercial counterparts. Further, the participation of indigenous microbes in fermentation may contribute to sensory complexity. This experiment illustrates the viability of native fermentation. Data collected shows differences in the speed of commercial and native ferments. PCR analysis demonstrated that while Saccharomyces does dominate native fermentation, certain microbes could be linked to elevated volatile acidity and malolactic fermentation. Analysis of finished wines demonstrated somewhat elevated sugar content in native replicates, variance in volatile acidity, and similarity in titratable acidity. Quantitative data from monoterpene analysis may provide further clarification upon receipt. These combined observations suggest that there may be a correlation between fermentation speed and yeast species, and between yeast species and flavor, and that extended research may be necessary.

Funding Support: FLCC, Cornell