IMPROVED METHOD FOR OBTAINING BIOETHANOL FROM SORGHUM GRAIN (SORGHUM BICOLOR L. MOENCH), COMPRISING STEPS INVOLVING DECORTICATION AND HYDROLYSIS WITH PROTEASES.

摘要

The invention relates to an improved method for obtaining bioethanol from sorghum grain (Sorghum bicolor L. Moench), comprising steps involving mechanical decortication and enzymatic hydrolysis with at least a protease prior to liquefaction. The decortication is performed mechanically and produces a by-product rich in pericarp or bran and stable sorghum grain or with a low humidity (10-15%), and the generation of a decorticated grain with a lower quantities of phenol inhibitors and a raw material producing greater quantities of bioethanol compared to the whole grain. The hydrolysis with protease, performed before and during the first part of the liquefaction step, enables the hydrolysis of the protein matrix covering the sorghum starch granules and provides a higher rate of hydrolysis of starch to dextrins and glucose after the liquefaction and saccharification steps respectively. The decorticated grain treated with protease, compared to the whole grain, provides musts with a higher a mount of fermentable sugars and alpha amino nitrogen, a 44% higher yield of bioethanol, a by-product resulting from the decortication stable to the environment and a reduced quantity of distillery spent-grains. The two novel steps of the method significantly reduce the biocatalysis and fermentation times such that ethanol can be produced in less time and using fewer resources.