An experimental study on whole paddy saccharification and fermentation for rice ethanol production

Whole paddy saccharification and fermentation (WPSF) was experimentally investigated to produce domestic bio-fuel or ethanol from rice for animal feed. More than 120 min of the high temperature soaking (HTS) promoted the gelatinization of the paddy due to an increase in the endosperm surface area. The calculated kinetic parameters evaluated based on the first-order reaction model revealed that the liquefaction and saccharification characteristics were improved by increasing the HTS time, while the roasting treatment enabled the HTS time to be shortened by 1.5 h. Fermentation combined with a longer HTS time resulted in increased ethanol production, while employing simultaneous saccharification and fermentation (SSF) produced an ethanol concentration and yield of 9% and 85%, respectively, using baker's dry yeast, which was more economical than using shochu dry yeast.

► A whole paddy saccharification and fermentation (WPSF) process was implemented for ethanol production.
► Costly shelling and milling of paddy are unnecessary for WPSF.
► Optimum WPSF is conducted at 35 °C with baker's dry yeast for about 105 h
► 9% EtOH mash and 89.5% EtOH yield are obtained from feedstuff paddy by WPSF.