| Abstrakt: |
Sweet potato residue (SPR), a by-product of sweet potato starch extraction, is full of starch and cellulose and could be used as the starting material for bioethanol production. A novel one-step complex enzyme (including α-amylase, glucoamylase, cellulase, hemicellulase, and pectinase) hydrolysis approach was developed to liberate the fermentable carbohydrates present in SPR. The effects of pH, amount of enzymes, solid-to-liquid ratio, temperature, and enzyme reaction time on the reducing sugar yield were investigated. Experiment results showed that the optimum pH, solid-to-liquid ratio, amount of enzymes, enzymatic hydrolysis temperature, and time were 4.5, 1: 7, 0.32 g, 50 ℃, and 6 h, respectively. Under these optimum conditions, the experimental reducing sugar yield reached 65.06% ± 1.62%. Carbohydrate analysis of the enzymatic SPR showed that glucose accounted for the largest proportion of fermentable sugars at 58.91% ± 1.25%. In particular, 64.98% ± 0.11% of the cellulose was decomposed during the enzymatic hydrolysis. Finally, a concentration of 113.63 ± 1.35 g/L glucose was formed from the 17.2% (w/v) SPR substrate, and 46.9 ± 0.61 g/L ethanol was finally produced by an industrial diploid Saccharomyces cerevisiae strain at a yield of 27.27% ± 0.30% SPR. The proposed approach has great potential for industrial bioethanol production from SPR due to its high productivity, easy manipulation, and environmentally friendly characteristics. [ABSTRACT FROM AUTHOR] |
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