Jared Johnson, Mengying Fu, James Osborne, and Michael Qian*
*Oregon State University, 100 Wiegand Hall, Department of Food Science and Technology, Corvallis, OR 97331 (michael.qian@oregonstate.edu)

This study investigated how prefermentation cold soak conditions impact Pinot noir wine aroma. In the first year of the study, Pinot noir wines were produced from grapes that were cold-soaked for six days at 6 or 10°C, with the addition of 0, 50, or 100 mg/L SO2. Six non-Saccharomyces yeast species, commonly isolated from grapes, were added at the start of cold soak and their populations monitored. Wine was also produced from grapes that did not undergo cold soak. At the end of cold soak, there were significant differences in a number of volatile compounds. Higher concentrations of isoamyl acetate were present in cold soaks conducted at 10°C than at 6°C, while higher concentrations of phenyl ethyl acetate were present in cold soaks conducted at 10°C with 100 mg/L SO2. There were also significant differences in the volatile aromas of the finished wines, particularly in esters. All wines made from cold-soaked grapes had significantly higher color and polymeric pigment content than the no-cold soak wine. In the second year of the study, an addition of Metschnikowia fructicola was made at the beginning of a six-day cold soak. At the end of cold soak, treatments with M. fructicola contained significantly more higher alcohols and lower acetate esters. In the finished wines, there were significant differences in volatile aromas between wines made from grapes that did or did not undergo a cold soak. Pinot noir wines produced without cold soak had significantly higher ethyl esters such as ethyl butyrate, ethyl isobutyrate, and ethyl octonoate. Wines made with M. fructicola also contained significantly higher concentrations of beta-citronellol than the no-cold soak treatment.

Funding Support: Oregon Wine Board