Evaluation of Yeast Strains during Fermentation of Riesling and Chenin blanc Musts

A. G. Reynolds; C. G. Edwards; M. A. Cliff; J. H. Thorngate; J. C. Marr

Abstract

Ten strains of Saccharomyces cerevisiae (V1116, D254, UCD 522, Bourgoblanc, EC1118, UCD 595, S6U, Wadenswil 27, 71B, T73) were evaluated in terms of their impact on the chemical composition of fermenting Riesling and Chenin blanc musts and on the sensory characteristics of their resultant wines. All yeasts completely utilized glucose present. Fructose concentrations in finished wines ranged from 1.5 to 7.0 g/L and were highest in UCD 595. Glycerol concentration was highest in Bourgoblanc and lowest in T73. Ethanol production was similar among the various strains, although UCD 522 produced higher ethanol than D254. Some differences existed between the yeasts in terms of production and/or use of six organic acids (citric, tartaric, malic, succinic, lactic, and acetic). Lowest tartaric and malic acids were found in 71B fermentations, while highest acetic acid concentrations were measured in both 71B and Wadenswil 27. Wadenswil 27 fermentations also contained highest tartaric, succinic (along with Bourgoblanc), and lactic acids. Highest citric acid was found in S6U fermentations, while both S6U and V1116 contained lowest acetic acid concentrations. T73 contained highest malate and lowest citrate. Sensory evaluation of Riesling wines showed that most yeasts produced more intense aromas and flavors than those fermented with EC1118. Wadenswil 27 produced Chenin blanc wines with more aroma and flavor intensity than EC1118.

Acknowledgments: The authors would like to thank Lallemand Corporation, Montreal, Canada, for financial support of this project and for the donation of the yeasts and Columbia Crest Winery, Paterson, WA, for grape juice and bottles. Thanks are also extended to Marjorie King and Kimberly Dever for technical assistance with sensory evaluation at Summerland.