Saccharification behavior of cellulose acetate during enzymatic processing for microbial ethanol production

• The potential application of cellulose acetate to enzymatic processing.
• Prior to saccharification, cellulose acetate was subjected to deacetylation.
• After deacetylation, enzymatic saccharification at 50 °C yielded 88.1–99.1%.
• Cellulose acetate exhibited a temperature dependence during saccharification.
• Presaccharification prior to SSF was found effective for increasing ethanol yield.

This study was conducted to realize the potential application of cellulose acetate to enzymatic processing, followed by microbial ethanol fermentation. To eliminate the effect of steric hindrance of acetyl groups on the action of cellulase, cellulose acetate was subjected to deacetylation in the presence of 1N sodium hydroxide and a mixture of methanol/acetone, yielding 88.8–98.6% at 5–20% substrate loadings during a 48 h saccharification at 50 °C. Ethanol fermentation using Saccharomyces cerevisiae attained a high yield of 92.3% from the initial glucose concentration of 44.2 g/L; however, a low saccharification yield was obtained at 35 °C, decreasing efficiency during simultaneous saccharification and fermentation (SSF). Presaccharification at 50 °C prior to SSF without increasing the total process time attained the ethanol titers of 19.8 g/L (5% substrate), 38.0 g/L (10% substrate), 55.9 g/L (15% substrate), and 70.9 g/L (20% substrate), which show a 12.0–16.2% improvement in ethanol yield.