Impact of yeast on the aroma and flavour of Oregon Pinot Noir wine

Background and Aims: The impact of yeast strain and species on the aroma and flavour of Pinot Noir wine was investigated using grapes treated with high hydrostatic pressure (HHP) to inactivate naturally occurring yeast and bacteria. Methods and Results: Pinot Noir grapes were treated by HHP resulting in inactivation of all viable yeast and bacterial cells. Grapes were then inoculated with either Saccharomyces cerevisiae RC212, Assmanshausen (AMH), MERIT.ferm, S. cerevisiae bayanus EC1118, or a blend of MERIT.ferm and Kluyveromyces thermotolerans (SYMPHONY). Descriptive analysis of wines revealed significant differences in overall fruity, red fruit, dark fruit, and jammy/cooked aromas. Principle component analysis showed wines produced by EC1118 and RC212 were characterized by higher dark fruit and jammy aromas while MERIT.ferm produced wine characterized by red fruit and floral aromas. Wines produced from AMH and SYMPHONY trended towards higher overall aged aromas and lower fruity and floral aromas. Conclusions: Yeast strain significantly impacted Oregon Pinot Noir wine aroma with some yeast strains producing wines with increased red and dark fruit aromas while others had reduced fruity aromas and higher aged aromas. Growth of Kluyveromyces thermotolerans during the early stages of fermentation resulted in a decrease in red fruity aromas. Significance of Study: Use of HHP in combination with sterile micro-fermentors allowed the impact of specific yeast on Pinot Noir aroma and flavor to be investigated. Differences in fruity aromas between Pinot Noir wines fermented by different yeast, including a non-Saccharomyces yeast, suggest that yeast strain and species can have a significant impact on Pinot Noir aroma.