Miguel Pedroza,* Andrew Nalle, Fatima Chavez, Claire Imperial, and Emily Wilkins
*California State University, Fresno, 2360 E. Barstow Ave., Fresno, CA, 93740 (miguelp@csufresno.edu)

Non-Saccharomyces yeasts are increasingly being used to diversify wine flavor profiles by producing metabolites that modulate the aroma, taste, and mouthfeel of wines. Among the currently available non-Saccharomyces yeasts, Pichia kluyveri stands out for developing a film on the surface of wine during the first days of fermentation, producing fermentative metabolites such as esters, thiols, and glycerol, and reducing ethanol. These effects may be susceptible to the inherent juice quality of different grape varietals. The aim of this research is to assess the effects of sequential inoculation with P. kluyveri on the fermentation kinetics and chemical composition of red and white wines. The experimental design included four grape varietals (Chardonnay, Cabernet Sauvignon, Muscat, and Zinfandel) and two fermentation styles (sequential inoculation with P. kluyveri followed by Saccharomyces cerevisiae and traditional inoculation with only S. cerevisiae). All treatment conditions were done in triplicate. Fermentation curves showed that sequential inoculation wines could take one to three additional days to finish fermentation due to the extended lag phase induced by the development of P. kluyveri. The fermentation rates during the S. cerevisiae stage were not affected by the sequential inoculation treatment. The effect on pH, residual sugars, volatile acidity, ethanol, and glycerol was heterogenous within varietals. Ongoing sensory evaluation is expected to reveal key attributes and preferences between the fermentation styles using a consumer panel.

Funding Support: CSU Agricultural Research Institute Gusmer Enterprises