Production of bioethanol from wild cassava crude starch (Manihot glaziovii Muell. Arg) using different microbial types and fermentation times

Abstract

Wild cassava (Manihot glaziovii Muell. Arg) is one of the varieties of cassava that contains toxic compounds cyanogenic glucosides, which cause unmarketable food products more suitable to be processed into bioethanol. This wild cassava plant produces tubers four times in weight compared to that of ordinary cassava, and the flesh contains about 40–70% starch by dry weight. This study aimed to determine the effect of the microbial types and fermentation times on bioethanol production from M. glaziovii Muell. Arg crude starch and to determine the type of microbes and fermentation time that can produce the highest bioethanol product from M. glaziovii Muell. Arg crude starch. This study consists of two factors using a factorial randomized block design (RBD). The first factor was the type of microbe which consists of 2 different microbes, namely R5I3 isolates and Saccharomyces cerevisiae ATCC 9763. The second factor was the fermentation time which consists of 4 levels, namely 3, 4, 5 and 6 days. The observed parameters were total dissolved solids value, pH value, reducing sugar content, and ethanol content. The data obtained were analyzed using analysis of variance (ANOVA) and continued with Tukey’s HSD post hoc tests. The results showed that fermentation using R5I3 isolates with a fermentation time of 5 days was the best treatment to obtain a maximum ethanol of 21.64±3.03 g/L, with a final pH value of 4.70±0.14, total dissolved solids 4.10±0.14°Brix and reducing sugar content of 0.91±0.02 g/L. Therefore, the new isolate R513 was highly potential for producing bioethanol from wild cassava crude starch.