Method for improving corn starch extractability

Abstract

The present invention relates to the transformation of maize with a grain softness-enhancing gene for improving corn starch extractability. The invention more particularly concerns the reduction of wet milling time using genetically transformed corn that expresses puroindoline.

1 . Use of a maize that has been transformed so as to express a grain softness-enhancing gene, as a source of corn with improved starch extractability.  
     
     
         2 . The use according to  claim 1 , wherein said grain softness-enhancing gene is a puroindoline gene.  
     
     
         3 . The use according to  claim 1  or  2 , wherein said transformed maize expresses puroindoline-a and/or puroindoline-b.  
     
     
         4 . A method of improving starch extractability comprising cultivating a maize transformed with a grain softness-enhancing gene and harvesting corn produced by said maize.  
     
     
         5 . The method according to  claim 4 , wherein said grain softness-enhancing gene is a puroindoline gene.  
     
     
         6 . The method according to  claim 4  or  5 , wherein said transformed maize is obtained by introducing a nucleic acid sequence which encodes a puroindoline-b protein into at least a maize cell and cultivating such transformed cell in conditions for regenerating fertile stable transformed maize plant.  
     
     
         7 . The method according to  claim 4  or  5 , wherein said transformed maize is obtained by introducing a nucleic acid sequence which encodes a puroindoline-a protein into at least a maize cell and cultivating such transformed cell in conditions for regenerating fertile stable transformed maize plant.  
     
     
         8 . The method according to any of  claims 4  to  7 , wherein said transformed maize is obtained by introducing a nucleic acid sequence which encodes a puroindoline-b protein and a nucleic acid sequence which encodes a puroindoline-a protein into a maize cell and cultivating such transformed cell in conditions for regenerating fertile stable transformed maize plant.  
     
     
         9 . An improved process of extracting corn starch, comprising wet milling a corn that has been transformed so as to express a grain softness-enhancing gene to provide corn starch.  
     
     
         10 . The process according to  claim 9 , wherein said corn expresses a puroindoline protein.  
     
     
         11 . The process according to  claim 9  or  10 , wherein said corn expresses puroindoline-a and/or puroindoline-b.  
     
     
         12 . The process according to any of  claims 9  to  11 , wherein the overall time necessary to achieve a starch extraction yield of at least a 95% is below 30 hours.  
     
     
         13 . The process according to any of  claims 9  to  12 , wherein the overall time necessary to achieve a starch extraction yield of at least a 95% is below 24 hours.  
     
     
         14 . The process according to any of  claims 9  to  13 , wherein the number of washes of the starch separation step is reduced by at least 50% as compared to milling of corn without increased grain softness.  
     
     
         15 . The process according to any of  claims 9  to  14 , wherein the number of washes of the starch separation step is between 2 to 4.