Isolation And Screening Of Excellent Wine Yeast And Fermentation Performance

In this research, for improving the flavor of the wine, yeasts were separated from the grape coat as well as branch, leaves and soil of orchards. Compared with the three grades including the aroma property. After selected by three grades, the laboratory preserved strain YU2 and its mutagenesis strains were compared by the ferment property such as ferment kinetic at low temperature.The results show that one strain was got which showed pleasure aroma and vigorous fermentation property. It was preliminarily identified as Hansenula anomala and named S15.3 which was not poisonous to human being and could be adapted to various temperature and pH in large range, standing 10%～ 15% sugar content and 25% alcoholic strength , so it could be applied to the production of various fruit wine; one strain that showed hereditary character stability and perfect ferment property had been gained, which could be used to the production of grape wine and other fruit wine.The optimal ferment temperature of S15.3 was 15-20°C and the optimal ferment parameters of YU2.28 were as follows: temperature 20°C, pH from 4.0 to 4.5 and oxygen provided intermittently. All those suggested that the two stains could ferment well at low temperature, adapt to group juice and wide ranging temperature, can showed remarkably advantages in fermentation rate and adaptation.The mixture of YU2.28 with S15.3 at 1:3 made the wine light color, clarified, clear and soft taste and harmonious body. Several aroma components such as esters & alcoholic aldehyde were detected by GC/MS. They also could make the wine pure and nice without lowing nutritional abundance and favorable aroma.We also studied the culture medium and culture condition of the ester-producedyeast, the result showed that: the ester-produced yeast can produce high level of esterwith low cost only when fermented at pH of 5.5 and temperature of 18°C with 2%ethanol and 0.1% acetic acid.