Process for conversion of granular starch to ethanol

Abstract

The present invention concerns a method of producing glucose from a granular starch substrate comprising, contacting a slurry comprising granular starch obtained from plant material with an alpha-amylase at a temperature below the starch gelatinization temperature of the granular starch to produce oligosaccharides and hydrolyzing the oligosaccharides to produce a mash comprising at least 20% glucose and further comprising fermenting the mash to obtain ethanol.

1 - 31 . (canceled) 
     
     
         32 . A method of producing a mash comprising contacting a corn slurry, comprising granular starch obtained by dry milling whole corn without removing the germ and bran fractions, with an exogenous a-amylase at a temperature below the starch gelatinization temperature of the granular starch to produce a mash comprising at least 30% (w/w) of the soluble starch substrate in the form of glucose, wherein the contacting is conducted for a period of 5 minutes to 48 hours at a pH of 3.5 to 7.0, and wherein no exogenous starch-hydrolysing enzymes other than the alpha-amylase are added to the corn slurry during the contacting step. 
     
     
         33 . The method according to  claim 32 , wherein the contacting is conducted for a period of 2 to 24 hours. 
     
     
         34 . The method according to  claim 32 , wherein the temperature is 45° C. to 70° C. 
     
     
         35 . The method according to  claim 32 , wherein the contacting step is conducted at a pH of between 4.0 and 6.0. 
     
     
         36 . The method according to  claim 32 , wherein the corn slurry has 20% to 45% dry solids (DS) granular starch. 
     
     
         37 . The method according to  claim 32 , wherein the corn slurry further comprises thin stillage and/or backset. 
     
     
         38 . The method according to  claim 32 , wherein the mash comprises at least 50% (w/w) of the soluble starch substrate in the form of glucose. 
     
     
         39 . The method according to  claim 32 , wherein the mash comprises at least 50% (w/w) of the soluble starch substrate in the form of glucose. 
     
     
         40 . The method according to  claim 39 , further comprising fermenting the mash in a separate reaction vessel in the presence of a fermenting microorganism and a starch hydrolyzing enzyme at a temperature of between 10° C. and 40° C. for a period of time of 10 hours to 250 hours to produce an end product. 
     
     
         41 . The method according to  claim 40 , further comprising recovering the end product. 
     
     
         42 . The method according to  claim 41 , wherein the end product is an alcohol. 
     
     
         43 . The method according to  claim 42 , further comprising recovering a fermentation co-product.