Potential use of low quality sweet potato for bioethanol production by Saccharomyces cerevisiae TISTR5339

Supasit Chooklin


This study was aimed to investigate optimal condition of ethanol production from low quality sweet potato (LQSP) was destroyed with sweet potato weevil in acid hydrolysis and fermentation. The main compositions of LQSP were starch and fiber composing of 55.25 and 10.29%, respectively as starch can be hydrolyzed to reducing sugar for ethanol fermentation. Acid hydrolysis was evaluated in production of maximum reducing sugar concentration of LQSP, which can be utilized later for ethanol fermentation. It was found that the maximum reducing sugar concentration of 390.99±5.35 g/L was obtained in the hydrolysis condition with 1% (v/v) of sulfuric acid and 25% (w/v) of LQSP. The effects of ammonium sulphate content (0.05-0.15%), pH (4.5-5.5) and inoculum content (5-10%) on ethanol production was determined with response surface methodology (RSM) with Box-Behnken experiment design of a total 17 sets of experiments. The maximum experimental ethanol production of 5.98 g/L was obtained with 0.05% of ammonium sulphate, pH 5.5 and 5.0% of inoculum size in the fermentation of 10% (v/v) inoculum size to 90 mL LQSP based medium and incubated at 30 ºC for 48 h. From these conditions, the scale-up of ethanol production was performed in 9 L fermenter and it provided the maximum ethanol yield of 5.04 g/L.As this study could mention that LQSP had a potential as substrate for ethanol production.



Low quality sweet potato, acid hydrolysis, ethanol, Saccharomyces cerevisiae, response surface methodology


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Last updated: 13 February 2019