TY - JOUR T1 - Yeast Assimilable Nitrogen (YAN) Optimization for Cool-Climate Riesling JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. DO - 10.5344/ajev.2018.17087 SP - ajev.2018.17087 AU - Camila M. Tahim AU - Anna Katharine Mansfield Y1 - 2018/12/21 UR - http://www.ajevonline.org/content/early/2018/12/13/ajev.2018.17087.abstract N2 - Adequate yeast sssimilable nitrogen (YAN) concentration is necessary for successful wine fermentation; therefore, supplementing musts with nitrogen is a common industry practice. In the Finger Lakes region of New York, Riesling (Vitis vinifera L.) often has YAN concentrations below the 140 mg/L considered a practical minimal limit. However, little research exists to confirm nitrogen requirements for cool-climate cultivars and conditions. To test the influence of juice nitrogen concentration on desirable sensory characteristics, a Riesling juice of 20 Brix and 130 mg/L initial YAN was supplemented with diammonium phosphate (DAP) to increase YAN to 180, 250, and 300 mg/L. Each supplemented fraction and the unaltered control were inoculated with three different Saccharomyces cerevisiae yeast strains: EC1118 (Lallemand), W15 (Lallemand), and Côte des Blancs (Red Star). The control concentration of 130 mg N/L was enough to complete fermentation for the three yeast strains studied, and further supplementation improved fermentation kinetics only for EC1118. Nitrogen supplementation affected the concentration of eight of the 10 select volatile compounds analyzed in at least one of the yeast strains. Of these, the concentration of most esters increased with nitrogen supplementation, with the exception of ethyl cinnamate, which decreased. Concentrations of higher alcohols 1-hexanol and 2-phenylethanol decreased, and decanoic acid increased, with increased nitrogen. Linalool and 1,1,6-Trimethyl-1,2-dihydronaphthalene, two volatiles associated with “varietal character” in Riesling, were not affected. In a preference ranking test, panelists preferred the unsupplemented control (130 mg N/L) over the supplementation treatments for wines fermented with EC1118. No difference in preference was found for W15 and Côte des Blancs treatments. ER -