Ethanol Production from Starch by Hydrolysis and Fermentation

Abstract

At present amylase is used for hydrolysis of starch before alcohol fermentation. Ethanol production from starch after hydrolysis of starch by acid was studied in this paper. Hydrochloric acid was used for hydrolysis. Different acid concentration and time were used for hydrolysis. We have used four substrates: soluble starch, insoluble starch, jwar (sorghum) and sweet potato. Jwar (sorghum) and sweet potato are starchy substrates available in plenty. These substrates we have used. We observed 92.79% hydrolysis with 13.33% soluble starch, 16.66% HCl concentration for 30 minutes. We observed 96.51% hydrolysis of insoluble starch (14.28%) by 20.63% HCl when 20 minutes heating time was used. In case of jwar we found 69.23% hydrolysis where 17.85% jwar (sorghum) was treated with 20.63% HCl for 30 minutes heating. We got 62.08% hydrolysis for 14.28% sweet potato starch treated with 20.63% HCl for 30 minutes heating. pH adjustment of hydrolyzate was studied. NaOH, NaOH with potassium phosphate for buffering action, calcium hydroxide, calcium carbonate were studied for pH adjustment. These hydrolyzate were subjected to fermentation after adjusting pH. Baker's yeast was used for fermentation. Fermentation was carried out at temperature 28°C without shaking for 24h. We have obtained 4.37, 4.57 and 3.61% ethanol from fermentation soluble starch, insoluble starch and jwar (sorghum) hydrolyzate respectively.