Fermentation product production processes
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.
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 , 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 , 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).