Hoang Duc Toan Le and Van Viet Man Le

pp. 663 - 667

Abstract

Immobilized yeast on nipa leaf sheath pieces was applied to ethanol fermentation using the medium with different
initial pH values (5.1, 4.5, 4.0, and 3.5). Control samples with the free yeast were also carried out under the same conditions.
Low pH value of 4.0 or 3.5 significantly reduced yeast growth and increased the residual sugar level in the fermentation
broths for both the immobilized and free cells. In all cases, the ethanol content produced and ethanol formation rate of the
immobilized yeast were 13-33% and 35-69%, respectively, higher than those of the free yeast. In addition, the residual sugar
content in the immobilized yeast cultures was 2.1-20.5 times lower than that in the free yeast cultures. The yeast immobilized
on nipa leaf stem pieces exhibited higher alcoholic fermentation performance than the free yeast in medium with low pH
value. This support was potential for further research for application in ethanol industry.