Patent ID: 9725742
Date: 2017-08-08
CPC Classifications: A23K,C07C,C12P,Y02E,Y02P

Claim:
1. A process for producing ethanol, the process comprising: forming an acidic aqueous medium comprising a plant matter feedstock and having a pH of from about 2 to about 6, wherein the plant matter comprises starch and another polysaccharide selected from the group consisting of cellulose, hemicellulose, and combinations thereof; hydrolyzing at least a portion of the starch, the another polysaccharide, or both in the acidic aqueous medium at a temperature of at least 85° C.; contacting at least a portion of the starch in the acidic aqueous medium with an α-amylase, which catalyzes enzymatic hydrolysis of at least a portion of the starch to yield an enzymatic hydrolysate containing simple sugars having from one to three saccharide units; and contacting the enzymatic hydrolysate in a simultaneous saccharification-fermentation (SSF) zone with a yeast, a glucoamylase, and a polysaccharide enzyme selected from the group consisting of cellulase, hemicellulase, and combinations thereof to form a saccharification-fermentation mixture, wherein the polysaccharide enzyme catalyzes the hydrolysis of at least a portion of the another polysaccharide to simple sugars having from one to four saccharide units, wherein said polysaccharide enzyme is introduced into the SSF zone after introduction of the yeast and glucoamylase into the SSF zone, wherein during a saccharification-fermentation period at least a portion of the simple sugars derived from the starch are converted by fermentation to produce ethanol within the SSF zone and at least a portion of the simple sugars derived from the another polysaccharide are converted by fermentation to produce ethanol within the SSF zone, wherein said polysaccharide enzyme is introduced at a point within from about 10% to about 80% of the duration of the saccharification-fermentation period; and wherein the process provides an ethanol yield increase of at least 2% as compared to the yield for a same process for producing ethanol that does not include introduction of said polysaccharide enzyme into the SSF zone.