Sourdough and process for producing same

A process for producing a sourdough in which the following steps take place consecutively:

• a) washing a fermentable matrix in water by completely submerging it in water and allowing the water to flow until it runs clear so as to obtain a washed matrix to be incubated, which either is still containing 200 g to 1.5 kg of residual water per 2 kg of washed matrix to be incubated, or is containing less than this and, in the latter case, submerging the washed matrix to be incubated in water at between 15° C. and 35° C. at the ratio of 1 kg to 20 kg of water per 2 kg of washed matrix to be incubated,
• a1) incubating said washed matrix to obtain an incubated matrix with a liquid phase, known as a liquor, and a solid phase,
• wherein if the washed matrix to be incubated is submerged in water, then said incubation takes place at between 10 and 35° C. until bubbles appear on the surface of the liquor so as to obtain the incubated matrix,
• b) separating the liquor from the rest of the incubated matrix,
• c) mixing the liquor with a substrate to obtain a mixture with a dry matter content by weight ranging between 15 and 60% and allowing this mixture to ferment for 12 to 72 hours at between 9° C. and 25° C. to obtain a medium and
• d) adding additional substrate and water at between 10° C. and 35° C. to the medium to obtain a product, the addition of additional substrate and water representing 25 to 75% of the total volume, and allowing fermentation for between 12 to 72 hours at between 9° C. and 25° C. while blowing with air, oxygen or a mixture containing oxygen, at a rate ranging from 0.01 m3h/kg of product to 10 m3/h/kg of product, to obtain sourdough.