Method for the production of an aqueous glucose solution

Abstract

The present invention relates to a process for the production of an aqueous glucose solution from maize or maize kernels. The invention also relates to a glucose solution obtainable by this process, and to its use for the production of organic compounds. The process according to the invention comprises: a) fractionating dry milling of maize kernels, where the maize kernels are separated into a maize-starch-comprising endosperm fraction and a high-oil germ fraction and, if appropriate, a bran fraction; b) enzymatic liquefaction and saccharification of the maize starch in an aqueous suspension of the endosperm fraction, which gives an aqueous glucose solution comprising maize gluten; and c) depletion of the maize gluten and, if appropriate, any bran present from the aqueous glucose solution.

1 . A process for the production of an aqueous glucose solution from maize, comprising:
 a) fractionating dry milling of maize kernels, where the maize kernels are separated into a maize-starch-comprising endosperm fraction and a high-oil germ fraction and optionally a bran fraction;   b) enzymatical liquefaction and saccharification of the maize starch in an aqueous suspension of the endosperm fraction, which gives an aqueous glucose solution comprising maize gluten; and   c) depletion of the maize gluten and optionally any bran present from the aqueous glucose solution;   where in step b) an aqueous suspension of the maize flour obtained in step a) and containing the endosperm fraction and optionally the bran fraction is employed, where the amount of maize flour is chosen in such a way that the aqueous suspension comprises from 30 to 45% by weight of starch, based on the total weight of the suspension.   
     
     
         2 . The process of  claim 1 , wherein the milling in step a) is carried out in the presence of from 1 to 30% by weight of water, based on the weight of the maize kernels employed. 
     
     
         3 . The process of  claim 1 , wherein, in step a), essentially only the germ fraction and the bran fraction are separated from the endosperm fraction. 
     
     
         4 . The process of  claim 1 , wherein, in step a), the bran fraction and the germ fraction are separated from the endosperm fraction and some of the bran fraction is returned to the endosperm fraction. 
     
     
         5 . The process of  claim 1 , wherein, in step a), the endosperm fraction is milled to a mean particle size in the range of from 0.1 to 1.0 mm. 
     
     
         6 . The process of  claim 1 , wherein, to carry out the liquefaction, the aqueous suspension of the endosperm fraction is heated to a temperature above the gelatinization temperature of the maize starch. 
     
     
         7 . The process of  claim 1 , wherein at least 90% of the maize gluten, based on the total gluten constituents present in the glucose solution, are separated from the aqueous glucose solution. 
     
     
         8 . The process of  claim 1 , wherein the depletion of the maize gluten and bran constituents which may be present is carried out in such a way that the glucose solution comprises less than 10% by volume of solids after the depletion. 
     
     
         9 . A glucose solution obtained by the process of  claim 1 . 
     
     
         10 . The glucose solution of  claim 9  comprising, based on the dry matter content,
 a) 80 to 97% by weight of sugars in the form of glucose and optionally disaccharides, 
 b) 1 to 7% by weight of crude protein, 
 c) 0.001% to 0.1% by weight, of crude fiber, 
 d) 200 to 1500 mg/kg of free amino acids, and 
 e) 0.01 to 1% by weight of crude ash constituents. 
 
     
     
         11 . The glucose solution of  claim 9  with a glucose concentration of at least 60% by weight, based on the total weight of the glucose solution. 
     
     
         12 . A process for the production of an organic substance comprising utilizing the glucose solution of  claim 9  as a carbon source. 
     
     
         13 . The process of  claim 12 , wherein the glucose solution is used as a glucose source for the fermentative production of the organic substance. 
     
     
         14 . A process for the production of an organic substance by fermentation, comprising the following steps:
 i. providing a glucose solution of  claim 9 , and   ii. adding the glucose solution to a fermentation medium which comprises a microorganism capable of overproducing the organic substance.   
     
     
         15 . The process of  claim 14 , wherein the organic substance is selected from among mono-, di- and tricarboxylic acids which have 3 to 10 carbon atoms and which optionally have hydroxyl groups attached to them, proteinogenic and nonproteinogenic amino acids, purine bases, pyrimidine bases; nucleosides, nucleotides, lipids, saturated and unsaturated fatty acids, diols having 4 to 10 carbon atoms, polyhydric alcohols having 3 or more hydroxyl groups, long-chain alcohols having at least 4 carbon atoms, carbohydrates, aromatic compounds, vitamins, provitamins, cofactors, neutraceuticals, proteins, yeasts, carotenoids, ketones having 3 to 10 carbon atoms, lactones, polyhydroxyalkanoates, polylactides, polysaccharides, polyisoprenoids, polyamides, and cyclodextrins. 
     
     
         16 . The process of  claim 14 , wherein the organic substance is an amino acid. 
     
     
         17 . The process of  claim 16 , wherein the amino acid is selected from among lysine, methionine, threonine, and glutamate. 
     
     
         18 . The process of  claim 15 , wherein the organic substance is selected from among vitamins and provitamins. 
     
     
         19 . The process of  claim 15 , wherein the organic substance is selected from among aliphatic mono-, di- and tricarboxylic acids having 2 to 10 carbon atoms. 
     
     
         20 . The process of  claim 15 , wherein the organic substance is selected from among aliphatic hydroxycarboxylic acids having 3 to 10 carbon atoms. 
     
     
         21 . The process of  claim 15 , wherein the organic substance is selected from among alkanediols having 3 to 10 carbon atoms. 
     
     
         22 . The process of  claim 15 , wherein the organic substance is selected from among aliphatic ketones having 3 to 10 carbon atoms. 
     
     
         23 . The process of  claim 15 , wherein the organic substance is selected from among aliphatic diamines having 3 to 10 carbon atoms. 
     
     
         24 . The process of  claim 15 , wherein the organic substance is selected from among nucleotides. 
     
     
         25 . The process of  claim 15 , wherein the organic substance is selected from among disaccharides, oligosaccharides, and polysaccharides. 
     
     
         26 . The process of  claim 15 , wherein the biomass resulting from the microorganism is separated from the overproduced organic substance of the fermentation product, and wherein a composition comprising biomass is obtained. 
     
     
         27 . A maize gluten obtained by the process of  claim 1 . 
     
     
         28 . The maize gluten of  claim 27 , which comprises the following constituents:
 a) 20 to 55% by weight of maize protein;   b) 2 to 45% by weight of sugar;   c) 0.5 to 10% by weight of vegetable fats and/or vegetable oils;   d) up to 10% by weight of crude fiber constituents; and   e) up to 15% by weight of other solid constituents,   
       where the amounts given are based on the dry matter of the maize gluten. 
     
     
         29 . The maize gluten of  claim 27  in the form of a powder. 
     
     
         30 . The maize gluten of  claim 29 , wherein the powder particles of the maize gluten have a mean particle size in the range of from 50 to 600 μm. 
     
     
         31 . A formulation auxiliary comprising the maize gluten of  claim 27 . 
     
     
         32 . The formulation auxiliary of  claim 31  for the formulation of biomass generated in a fermentation. 
     
     
         33 . A component in feedstuffs comprising the maize gluten of  claim 27 . 
     
     
         34 . A feedstuff composition, consisting essentially of the biomass generated in a fermentation, maize gluten of  claim 27  and optionally the germ fraction.