Method for simultaneously producing lactic acid and alcohol or biogas from cereals

A continuous process for the simultaneous production of lactic acid and of a second fermentation product starting from cereals, the process comprising:

• dry milling cereals using a mill to form a milled product;
• recovering the milled product and mixing it in a mixer with a stream of water to create a slurry;
• subjecting the slurry to a saccharification in a reactor and producing a crude dextrose stream;
• separating, in a separator, the crude dextrose stream into a first flow comprising a liquid flow and a second flow comprising solid part;
• removing an oil resulting from the milling and occurring in the liquid flow for subsequent treatment, and recovering a purified dextrose flow;
• producing a fermentation product in the form of a lactic acid by subjecting the purified dextrose flow to a selective separation of sugars to recover a purified flow and a flow rich in oligosaccharides, before subjecting the purified flow to a fermentation in the presence of a microorganism appropriate for producing the lactic acid;
• recovering the solid dextrose flow via a first pipe containing products which are difficult to ferment, and recovering the flow rich in oligosaccharides via a second pipe, to hydrolyze contents of the first and second pipes in a reactor under hydrolysis conditions and to convert the contents into a fermentable dextrose flow;
• and
• subjecting the fermentable dextrose flow to a fermentation in a fermenter to produce a second fermentation product.