Secondary Liquefaction in Ethanol Production

Abstract

The invention relates to a method of producing ethanol by fermentation, said method comprising a secondary liquefaction step in the presence of a thermostable acid alpha-amylase or a thermostable maltogenic acid alpha-amylase.

1 - 58 . (canceled)  
     
     
         59 . A method of producing ethanol, comprising; 
 a) liquefaction of a starch containing material in the presence of an alpha-amylase;    b) jet cooking the liquefied starch,    c) a secondary liquefaction in the presence of a thermostable acid alpha-amylase; wherein the thermostable acid alpha-amylase maintains more than 90% of its activity for 1 hour at 70° C. using a DE 12 alpha-amylase TTC liquefied corn starch at 30% dry substance as substrate, pH 5.5, 0.1 M citrate buffer and 4.3 mM Ca+ 2+ ;    d) saccharification; and    e) fermentation to produce ethanol;    wherein steps (a), (b), (c), and (d) are performed in the order (a), (b), (c), (d), and wherein step (e) is performed simultaneously to or following step (d).    
     
     
         60 . The method of  claim 59 , further comprising recovering the ethanol.  
     
     
         61 . The method of  claim 59 , further comprising a pre-saccharification step which is performed after the secondary liquefaction in step (c) and before step (d), wherein the pre-saccharification comprises treating the starch with a glucoamylase at a temperature in the range of 30-65° C.  
     
     
         62 . The method of  claim 59 , wherein the starch containing material is selected from the group consisting of tubers, roots, whole grain, and any combination thereof.  
     
     
         63 . The method of  claim 59 , wherein the starch containing material is obtained from cereal.  
     
     
         64 . The method of  claim 59 , wherein the starch containing material is selected from the group consisting of corns, cobs, wheat, barley, rye, milo, potatoes, and any combination thereof.  
     
     
         65 . The method of  claim 59 , wherein the starch containing material is whole grain selected from the group consisting of corn, wheat, barley, and any combination thereof.  
     
     
         66 . The method of  claim 59 , wherein the starch containing material is whole grain and said method comprises a step of milling the whole grain before step (a).  
     
     
         67 . The method of  claim 59 , wherein the starch containing material is obtained by a process comprising milling of whole grain.  
     
     
         68 . The method of  claim 59 , further comprising prior to step (a) the steps of: 
 i) milling of whole grain;    ii) forming a slurry comprising the milled grain and water to obtain the starch containing material.    
     
     
         69 . The method of  claim 68 , wherein the milling is a dry milling step.  
     
     
         70 . The method of  claim 68 , wherein the milling is a wet milling step.  
     
     
         71 . The method of  claim 59 , wherein the starch-containing material is a side stream from starch processing.  
     
     
         72 . The method of  claim 59 , further comprising: 
 (f) distillation to obtain the ethanol;    wherein the fermentation in step (e) and the distillation in step (f) are carried out simultaneously or separately/sequential.    
     
     
         73 . The method of  claim 72;  wherein the starch containing material is milled whole grain, said method further comprising the steps of: 
 (g) separation of whole stillage produced by the distillation in step (f) into wet grain and thin stillage; and    (h) recycling the thin stillage to the starch containing material prior to step (a).    
     
     
         74 . The method of  claim 59 , wherein the fermentation in step (e) is performed using a yeast.  
     
     
         75 . The method of  claim 59 , wherein the fermentation is carried out in the presence of glucoamylase, phytase and/or protease.  
     
     
         76 . The method of  claim 75 , wherein the protease is an acid protease, a neutral protease or an alkaline protease.  
     
     
         77 . A method for producing ethanol, comprising: 
 a) liquefaction of a starch containing material in the presence of an alpha-amylase;    b) jet cooking the liquefied starch;    c) a secondary liquefaction in the presence of a thermostable maltogenic acid alpha-amylase; wherein the thermostable maltogenic acid alpha-amylase maintains more than 90% of its activity for 1 hour at 70° C. using a DE 12 alpha-amylase TTC liquefied corn starch at 30% dry substance as substrate, pH 5.5, 0.1 M citrate buffer and 4.3 mM Ca+ 2 ;    d) saccharifaction; and    e) fermentation to produce ethanol;    wherein steps (a), (b), (c) and (d) are performed in the order (a), (b), (c), (d) and wherein step (e) is performed simultaneously to or following step (d).    
     
     
         78 . The method of  claim 77 , wherein the thermostable maltogenic acid alpha-amylase having an amino acid sequence which is at least 95% identical to SEQ ID NO. 1.  
     
     
         79 . The method of  claim 77 , wherein the thermostable maltogenic acid alpha-amylase is SEQ ID NO: 1.  
     
     
         80 . The method of  claim 77 , further comprising recovering the ethanol.  
     
     
         81 . The method of  claim 77 , further comprising a pre-saccharification step which is performed after the secondary liquefaction in step (c) and before step (d), wherein the pre-saccharification comprises treating the starch with a glucoamylase at a temperature in the range of 30-65° C.  
     
     
         82 . The method of  claim 77 , wherein the starch containing material is selected from the group consisting of tubers, roots, whole grain, and any combination thereof.  
     
     
         83 . The method of  claim 77 , wherein the starch containing material is obtained from cereal.  
     
     
         84 . The method of  claim 77 , wherein the starch containing material is selected from the group consisting of corns, cobs, wheat, barley, rye, milo, potatoes and any combination thereof.  
     
     
         85 . The method of  claim 77 , wherein the starch containing material is whole grain selected from the group consisting of corn, wheat, barley, and any combination thereof.  
     
     
         86 . The method of  claim 77 , wherein the starch containing material is whole grain and said method comprises a step of milling the whole grain before step (a).  
     
     
         87 . The method of  claim 77 , wherein the starch containing material is obtained by a process comprising milling of whole grain.  
     
     
         88 . The method of  claim 77 , further comprising prior to step (a) the steps of: 
 i) milling of whole grain;    ii) forming a slurry comprising the milled grain and water to obtain the starch containing material.    
     
     
         89 . The method of  claim 88 , wherein the milling is a dry milling step.  
     
     
         90 . The method of  claim 88 , wherein the milling is a wet milling step.  
     
     
         91 . The method of  claim 77 , wherein the starch-containing material is a side stream from starch processing.  
     
     
         92 . The method of  claim 77 , further comprising: 
 (f) distillation to obtain the ethanol:    wherein the fermentation in step (e) and the distillation in step (f) are carried out simultaneously or separately/sequential.    
     
     
         93 . The method of  claim 92;  wherein the starch containing material is milled whole grain, said method further comprising the steps of: 
 (g) separation of whole stillage produced by the distillation in step (f) into wet grain and thin storage; and    (h) recycling the thin stillage to the starch containing material prior to step (a).    
     
     
         94 . The method of  claim 77 , wherein the fermentation in step (e) is performed using a yeast.  
     
     
         95 . The method of  claim 77 , wherein the fermentation is carried out in the presence of glucoamylase, phytase and/or protease.  
     
     
         96 . The method of  claim 95 , wherein the protease is an acid protease, a neutral protease or an alkaline protease.