Effect of yeast extract on ethanol production
Effect of yeast extract was studied by varying its con- centration from 1.0 to 3.0 g/l keeping rest of the para- meters at their optimal conditions. Figure 4 shows that as the concentration of yeast extract increased from 1.0 to 2.0 g/l, ethanol production was also increased from 6.55 to 7.11% for S. cerevisiae but above this concentration, ethanol production was decreased when potato (Kufri Bahar) was used as substrates. Nuanpeng et al. (2011) studied that sugar consumption, ethanol production and yeast cell viability during batch VHG fermentation of S. cerevisiae NP 01 from sweet sorghum juice supple- mented with various yeast extract concentrations and observed that the highest ethanol concentration in the EP medium containing 9.0 g/l of yeast extract. Laopaiboon et al. (2009) observed that ethanol production efficiency was improved when 3.0 g/l of yeast extract (120.68 ± 0.54 g/l) was added to sweet sorghum juice under VHG conditions.