Methods and systems for producing ethanol using raw starch and fractionation

Abstract

The present invention relates to methods for producing high levels of alcohol during fermentation of plant material, and to the high alcohol beer produced. The method can include fractionating the plant material. The present invention also relates to methods for producing high protein distiller's dried grain from fermentation of plant material, and to the high protein distiller's dried grain produced. The method can include drying a co-product by ring drying, flash drying, or fluid bed drying. The present invention further relates to reduced stack emissions from drying distillation products from the production of ethanol.

1 .- 7 . (canceled) 
     
     
         8 . A method for producing ethanol from reduced plant material, the method comprising:
 (a) filling a fermenter with reduced plant material during a filling phase over a fill period; and   (b) inoculating the fermenter with yeast during the fill period,   wherein the pH of a slurry in the fermenter is varied to reduce the likelihood of bacterial contamination early in fermentation and/or to increase yeast growth and fermentation during the latter stages of fermentation.   
     
     
         9 . The method of  claim 8 , wherein the pH is adjusted to about 3 to about 4.5 during a first half of the fill period. 
     
     
         10 . The method of  claim 8 , wherein the pH is adjusted to about 4.5 to about 6 during a second half of the fill period. 
     
     
         11 . The method of  claim 8 , wherein the yeast is conditioned in a prefermenter prior to inoculating the fermenter with the yeast. 
     
     
         12 . The method of  claim 11 , wherein the yeast is conditioned for at least 8 hours. 
     
     
         13 . The method of  claim 11 , wherein the yeast is aerated during conditioning in the prefermenter. 
     
     
         14 . The method of  claim 11 , wherein the prefermenter is from 1 to 10% of the volume of the fermenter. 
     
     
         15 . The method of  claim 11 , wherein the prefermenter is from 2.5 to 5% of the volume of the fermenter. 
     
     
         16 . The method of  claim 8 , wherein the bacterial contamination comprises lactic acid bacteria and/or acetic acid bacteria. 
     
     
         17 . The method of  claim 8 , further comprising adding fresh reduced plant material to the fermenter, wherein the pH of the fresh reduced plant material is the same as the varied pH of the slurry in the fermenter. 
     
     
         18 . The method of  claim 8 , wherein the pH of the slurry is not controlled after the yeast becomes established. 
     
     
         19 . The method of  claim 8 , wherein the reduced plant material comprises corn starch. 
     
     
         20 . The method of  claim 8 , wherein the reduced plant material is mixed with water. 
     
     
         21 . A method for producing ethanol from reduced plant material, the method comprising:
 (a) filling a fermenter with reduced plant material;   (b) achieving a pH of a slurry in the fermenter that is:
 (i) unfavorable for growth of contaminating bacteria, and 
 (ii) tolerable for yeast growth; 
   (c) inoculating the fermenter with yeast; and   (d) achieving a pH of the slurry that is favorable for yeast growth.   
     
     
         22 . The method of  claim 21 , wherein the reduced plant material comprises corn starch. 
     
     
         23 . The method of  claim 21 , wherein the reduced plant material is mixed with water. 
     
     
         24 . The method of  claim 21 , wherein the pH achieved in (b) is a pH between 3.0 and 4.5. 
     
     
         25 . The method of  claim 21 , wherein the pH achieved in (d) is a pH between 3.0 and 6.0. 
     
     
         26 . The method of  claim 21 , wherein the reduced plant material is added to the fermenter over a fill period, and wherein the fermenter is filled at a pH below 4.5 during a first half of the fill period. 
     
     
         27 . The method of  claim 26 , wherein the pH of the slurry is above 4.5 during a second half of the fill period. 
     
     
         28 . The method of  claim 8 , wherein the pH of the slurry is varied during the fill period.