Double Fermentation of Cassava Starch Leads to Higher Bioethanol Yield

Cassava starch is considered as a good potential source of commercial bioethanol due to its availability, low market price and suitability for large-scale biological production. Today, advancements in enzymology have made starch liquefying and saccharifying enzymes possible, in converting a complex starch polymer into valuable metabolites. These enzymatic treatments have allowed the production of free glucose which can be utilized in bioethanol production by microbial fermentation.

Several fungi were evaluated for amylase production, and Aspergillus fumigatus KIBGE-IB33 was selected based on maximum enzyme yield. The fungus was then utilized for cassava starch fermentation. After adding concentrated amylolytic enzyme mixture to the cassava starch slurry, for maximum glucose formation, it was further fermented using Saccharomyces cerevisiae into bioethanol with 84.0% yield. The distillate originated after recovery of bioethanol gave 53.0% yield.

An effective dual enzymatic starch degradation method was designed for the production of bioethanol using cassava starch. This developed technique is potentially more profitable due to its fast liquefaction and saccharification approach for the formation of glucose and ultimately resulted in higher yields of alcohol.