Liquefying aqueous starch slurry followed by saccharification with ion exchange resin

A process for converting the starch fraction derived from dry milled degerminated cereal grain to a sterile aqueous solution of fermentable sugar, said starch containing water insoluble protein, a relatively minor amount of the oil of the whole cereal grain, which comprises:

• (a) liquefying an aqueous slurry of the starch in the presence of an acid hydrolysis catalyst to provide sterile aqueous partial starch hydrolysate slurry containing the water insoluble protein in substantially unaltered condition;
• (b) separating the slurry resulting from liquefying step (a) into an aqueous sterile slurry of partial starch hydrolysate and an aqueous slurry of water insoluble protein;
• (c) saccharifying the aqueous slurry of partial starch hydrolysate in the presence of an acidic cationic exchange resin to provide a sterile aqueous solution of fermentable sugar;
• (d) diluting the aqueous slurry of water insoluble protein from step (b) with water;
• (e) separating water from the water insoluble protein resulting from step (d);
• and,
• (f) recycling the water recovered in step (e) for use in a subsequent liquefying step (a).