Fermentation product production processes

Abstract

The present invention relates to a process for producing a fermentation product from starch-containing material, comprising liquefying said starch-containing material with an alpha-amylase; treating with a protease; saccharifying in the presence of a carbohydrate-source generating enzyme; fermenting in the presence of a fermenting organism.

The invention claimed is: 
     
       1. A process for producing an alcohol from starch-containing material, comprising
 (a) liquefying said starch-containing material with an alpha-amylase;   (b) treating the liquefied mash from step (a) with a protease before initiating step (c);   (c) saccharifying in the presence of a carbohydrate-source generating enzyme;   (d) fermenting in the presence of a fermenting organism to produce the alcohol.   
     
     
       2. The process of  claim 1 , wherein steps (a) and (b) are carried out simultaneously or sequentially. 
     
     
       3. The process of  claim 1 , further comprising a step of:
 (e) distillation to obtain the alcohol.   
     
     
       4. The process of  claim 1 , wherein the alcohol is ethanol. 
     
     
       5. The process of  claim 1 , wherein step (a) is carried out using a bacterial alpha-amylase or a fungal alpha-amylase. 
     
     
       6. The process of  claim 1 , wherein the pH during liquefaction is from about 4.5 to 7. 
     
     
       7. The process of  claim 1 , further comprising, prior to the step (a), the steps of:
 i) milling of starch-containing material;   ii) forming a slurry comprising the milled starch-containing material and water.   
     
     
       8. The process of  claim 7 , wherein the slurry is heated to above the initial gelatinization temperature. 
     
     
       9. The process of  claim 7 , wherein the slurry is jet-cooked at a temperature of 95-140° C. before step (a). 
     
     
       10. The process of  claim 1 , A process for producing an alcohol from starch-containing material, comprising
 (a) liquefying said starch-containing material with an alpha-amylase; 
 (b) treating the liquefied mash from step (a) with a protease before initiating step (c); 
 (c) saccharifying in the presence of a carbohydrate-source generating enzyme; 
 (d) fermenting in the presence of a fermenting organism to produce the alcohol,
 wherein step (b) is carried out as a post liquefaction protease treatment. 
 
 
     
     
       11. The process of  claim 1 , wherein the protease is a bacterial protease derived from Bacillus or Nocardiopsis. 
     
     
       12. The process of  claim 1 , A process for producing an alcohol from starch-containing material, comprising
 (a) liquefying said starch-containing material with an alpha-amylase; 
 (b) treating the liquefied mash from step (a) with a protease before initiating step (c); 
 (c) saccharifying in the presence of a carbohydrate-source generating enzyme; 
 (d) fermenting in the presence of a fermenting organism to produce the alcohol, 
 wherein the protease is a plant protease derived from barley. 
 
 
     
     
       13. The process of  claim 1 , wherein step (b) is carried out at conditions optimal for the protease in question. 
     
     
       14. The process of  claim 1 , wherein the protease treatment in step (b) is carried out at a temperature of 25-90° C. 
     
     
       15. The process of  claim 1 , wherein the during protease treatment in step (b) is carried out at a pH of 2-11. 
     
     
       16. The process of  claim 1 , wherein the liquefied starch in step (b) has a concentration of 20-50% (w/w) Total Solids (TS). 
     
     
       17. The process of  claim 1 , wherein the protease treatment in step (b) is carried out for 0.1 to 12 hours. 
     
     
       18. The process of  claim 1 , wherein the protease is present at a concentration of 0.0001 to 1 wt.-% of TS. 
     
     
       19. The process of  claim 1 , wherein the saccharification in step (c) is carried out as a pre-saccharification step lasting for about 40 to 90 minutes, at a temperature of about 28-65° C. and a pH of 4-6, followed by complete saccharification during fermentation in a simultaneous saccharification and fermentation process (SSF). 
     
     
       20. A process for producing fuel ethanol, comprising
 (a) liquefying a gelatinized starch-containing material with an alpha-amylase to form a liquefied mash comprising dextrins and protein, and degrading the protein with a protease, at a temperature above the initial gelatinization temperature of the starch-containing material, wherein the starch-containing material is corn;   (b) subsequent to step (a), simultaneously saccharifying the dextrins in the presence of a glucoamylase to produce fermentable sugar and fermenting the fermentable sugar in the presence of a fermenting organism to produce a fermentation product; and   (c) distilling the fermentation product to recover fuel ethanol.    
     
     
       21. The process of  claim 20 , wherein the alpha-amylase is a bacterial alpha-amylase or a fungal alpha-amylase.  
     
     
       22. The process of  claim 20 , wherein the protease is a bacterial protease.  
     
     
       23. The process of  claim 20 , wherein the pH during liquefaction is maintained from between about 4.5 to 7.  
     
     
       24. The process of  claim 20 , further comprising, prior to the step (a), the steps of:
 i) milling the starch-containing material; and   ii) forming a slurry comprising the milled starch-containing material and water.    
     
     
       25. The process of  claim 24 , wherein the slurry is jet-cooked at a temperature of 95-140° C. before step (a) to form the gelatinized starch-containing material.  
     
     
       26. The process of  claim 24 , wherein milling is dry milling.  
     
     
       27. The process of  claim 20 , wherein the liquefied mash has a concentration of 20-50% (w/w) Total Solids (TS).  
     
     
       28. The process of  claim 20 , wherein the protease is present at a concentration of 0.0001 to 1 wt.-% of Total Solids.  
     
     
       29. The process of  claim 24 , further comprising jet-cooking the slurry at a temperature between 95-140° C. for 1-15 minutes.  
     
     
       30. The process of  claim 20 , wherein the gelatinized starch-containing material is obtained by heating a slurry of milled corn and water above the initial gelatinization temperature of corn.  
     
     
       31. The process of  claim 20 , further comprising a pre-saccharification step preceding step (b) lasting for about 40 to 90 minutes.