Patent ID: 7244597

Claim:
A method of producing ethanol by fermentation comprising a secondary liquefaction step, wherein said secondary liquefaction step is carried out in the presence of a thermostable acid alpha-amylase comprising the steps of: a) liquefaction of a starch containing material in the presence of an alpha-amylase; b) jet cooking the liquefied starch; c) followed by a secondary liquefaction in the presence of a thermostable acid alpha-amylase; whereby the enzyme will maintain more than 90% of its activity for 1 hour at 70.degree. C. for thermostability 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 and the enzyme will maintain more than 70% of its activity in the range from pH 3.8–4.7 using the substrate DE 12 alpha-amylase TTC liquefied corn starch at 30% dry substance, Temperature 40.degree. C., and 0.1 M citrate buffer and 4.3 mM Ca +2 d) saccharification; and e) fermentation to produce ethanol; wherein the steps (a), (b), (c) and (d) is performed in the order (a), (b), (c), (d) and wherein (e) is performed simultaneously to or following (d).