Isolation and Screening of Wine Yeasts from Grapes in Yalu River Valley China for Fermentation Performance

In order to further explore the diversity of yeast in grape brewing in Yalu River Valley, northern China and to better exploit and utilize the yeast resources in a grape producing area, we investigated soil, grape residue after juice extraction and naturally fermented grape juice samples collected from grape plantations in the Yalu River Valley in this study. Twelve yeast strains were identified using colony and cell morphology and molecular biology. Three Saccharomyces cerevisiae strains from different sources, EN2, BZ1 and EZ2, were selected to determine their acid, Sodium dioxide (SO₂), glucose and ethanol tolerance. The results showed that EN2 exhibited significant acid and SO₂ tolerance, while BZ1 and EZ2 exhibited significant glucose and ethanol tolerance. These three S. cerevisiae strains showed good growth and fermentation characteristics and could be used as development strains for brewing wine. Results of this study could be useful in breeding, wine yeast-strain research and wine product development.