Influence of initial pH and sulfur dioxide content in must on wine fermentation by immobilized yeast in bacterial cellulose

In this study, wine fermentation was carried out by yeast immobilized in bacterial cellulose (BC).The initial pH and sulfur dioxide content in must were adjusted from 3.5 to 4.5, and from 12 ppm to 312 ppm, respectively. The results indicated that the maximum specific growth rate of the immobilized yeast was 1.17 – 1.39 times more than that of the free yeast. Besides, the sugar uptake rate and ethanol production rate of the immobilized yeast were 1.04 - 1.41 times and 1.05 – 1.35 times, respectively, more than those of the free yeast. However, the ethanol production yield of the immobilized yeast was similar or slightly lower than that of the free yeast in must with low initial pH or high sulfur dioxide content. Application of immobilized yeast to must fermentation produced wine with low pH and volatile acid content and this led to an improvement in physicochemical, microbiological and sensory quality of the final product.