Evaluation of Fermentation Parameters of Elephant foot Yam (Amorphophalluspaeoniifolius) for Bioethanol Production

Bioethanol successfully finds its role in the development of renewable energy sources to supplement the world’s increasing demand in energy supply. In this study, elephant foot yam (Amorphophalluspeoniifolius), a starch-based crop, abundantly grown in tropical countries like Philippines, was used for the evaluation of the effect of substrate concentration and yeast loading (Saccharomyces cerevisiae) in Simultaneous Saccharification and Fermentation (SSF). In SSF, the optimum condition was observed at10% w/v substrate concentration in 20 mL yeast loadingwith an ethanol yield of 12.02 ± 0.21 %. As substrate concentration decreases and yeast loading increases, percent ethanol yield increases. Best mathematical model was generated to describe the relationship of the substrate concentration and yeast loading to ethanol yield. The generated quadratic model, 𝑌2.47 = 80.63 − 84.46 𝐴 + 126.73 𝐵 − 17.49𝐴𝐵 + 65.59𝐴2 + 91.02𝐵2 ,can explain 99.96 % (R2) of the variability in the yield. The statistical significance of the model was evaluated by F-test for analysis of variance (p<0.05). The results showed that the production of ethanol was more strongly affected by the variation of yeast loading. Using the best substrate concentration and yeast loading, ethanol yield was determined in SSF coupled with Acid Hydrolysis (SSF-AH) having an ethanol yield of 19.1952%. The results revealed that subjecting first the substrate to acid hydrolysis could increase the ethanol yield for it increased the reducing sugar of the substrate.

Keywords: Amorphophalluspaeonifolius, bioethanol, Elephant foot yam, fermentation, substrate concentration