System and process for starch production

Abstract

Use of a high shear mechanical device in a process for production of starch by hydration and disruption of corn kernel particles in the presence of sulfur dioxide or bisulfite ions makes possible a decrease in mass transfer limitations, thereby enhancing starch production. A system for production of starch is also provided in which a high shear mixing device is configured to receive an aqueous corn slurry from a pump that is disposed between the reactor and a gaseous sulfur dioxide inlet of the high shear mixing device. The high shear mixing device is also configured to generate a fine dispersion of sulfur dioxide bubbles and small corn particles in the slurry. A reactor is configured to receive the output from the high shear mixing device and to provide for starch production.

1 . A system for production of starch, comprising;
 a high shear mixing device having a corn slurry inlet, a sulfur dioxide inlet and a dispersion outlet, said mixing device being configured to produce a dispersion of corn kernel particles and submicron-sized sulfur dioxide bubbles and in an aqueous medium;   a reactor configured for receiving said dispersion, and having a slurry outlet and a product outlet;   a pump disposed between said slurry outlet and the slurry inlet of said high shear mixing device; and   a starch-gluten separator configured for receiving at least a portion of said product and separating said starch.   
   
   
       2 . The system of  claim 1 , wherein said high shear mixing device comprises a rotor-stator set having a tip, wherein said device is configured to produce a rotor tip speed of at least 22.9 m/sec. 
   
   
       3 . The system of  claim 1 , wherein said high shear mixing device comprises a rotor-stator set having a tip, wherein said device is configured to produce a rotor tip speed of at least 40 m/sec. 
   
   
       4 . The system of  claim 1  wherein the reactor comprises a batch reactor. 
   
   
       5 . The system of  claim 1  wherein the reactor comprises a continuously or semi-continuously stirred tank. 
   
   
       6 . The system of  claim 1  wherein said high shear mixing device comprises a first high shear mixing device, and the system further comprises at least one additional high shear mixing device in series flow alignment following said first mixer, said additional devices having progressively higher shear rates. 
   
   
       7 . The system of  claim 6  further comprising a protein separator and oil separator following at least one said additional mixer. 
   
   
       8 . The system of  claim 1  wherein said high shear mixing device comprises at least one generator comprising a rotor and a complementarily-shaped stator. 
   
   
       9 . The system of  claim 8  wherein said high shear mixing device is operable to provide a shear rate of at least 20,000 s −1 , wherein the shear rate is defined as the tip speed divided by the shear gap, and wherein the tip speed is defined as πDn, where D is the diameter of the at least one rotor and n is the frequency of revolution. 
   
   
       10 . The system of  claim 8  comprising at least two generators. 
   
   
       11 . The system of  claim 10  wherein at least one of the at least two generators provides a shear rate that is greater than the shear rate provided by another of the at least two generators, wherein the shear rate is defined as the tip speed divided by the shear gap, and wherein the tip speed is defined as πDn, where D is the diameter of the at least one rotor and n is the frequency of revolution. 
   
   
       12 . The system of  claim 1  further comprising a grinder fluidly connected with the reactor, wherein said grinder is configured for cracking corn kernels and loosening hulls of the corn kernels to provide a corn grist of a desired particle size. 
   
   
       13 . The system of  claim 12  further comprising a germ and hull separator positioned between the reactor and the grinder, wherein said germ and hull separator is configured to separate the corn hulls from the corn grist. 
   
   
       14 . The system of  claim 1  wherein said reactor further comprises an inlet for introducing water, bisulfite solution, or a combination thereof to said reactor. 
   
   
       15 . The system of  claim 1  further comprising a screening assembly fluidly connected with the product outlet of the reactor, wherein the screening assembly is configured for separating fiber from starch and gluten.