[Dry solid staging fermentation].

Very high gravity (VHG) ethanolic fermentation is a new perspective technology for the fuel ethanol production. Compared with traditional hot cook process in most ethanol plants, uncooked process using milled grain slurry in combination with granular starch hydrolyzing enzymes makes high gravity fermentation much easier to control. In this study, dry solids staging technique was first time reported in uncooked process for fermentation ethanol. We further studied the difference between the new process and the batch fermentation, including different initial fermentation concentrations and different starting times. The results showed that at the same dry solid concentration of 30% and the same enzyme dose at 0.22% (W/W), the final ethanol output of new process was increased to 18.50% (V/V) from 17.06% (V/V) of the conventional process. This study demonstrated the new application of uncooked fermentation technology.