Process for preparing a fermented food product, including more than 5 · 107, in particular more than 108 bifidobacteria per gram of fermented food product for a storage period of at least 30 days, in particular at least 35 days, from a starting material, comprising the following successive stages: - a planting stage of a starting material, optionally pasteurized, by inoculation of planting ferments containing from 4 · 106 to 1 · 107 bifidobacteria per ml of starting material , to obtain a seeded material, - a fermentation stage of the seeded material obtained in the previous stage, such that the fermentation start temperature is 36 to 38 ° C, the fermentation end temperature is 37 to 39 ° C , and the fermentation time is from 8 to 11 hours, to obtain a fermented material, - an intermediate cooling stage of the seeded material obtained in stage a Further, such that the intermediate cooling time is 1h30 to 2 hours, and the intermediate cooling temperature is 4 to 18 ° C, to obtain a precooled material, - a storage stage of the precooled material obtained in the previous stage, such that the storage time is less than 15 hours, to obtain a stored material, - a final cooling stage of the stored material obtained in the previous stage, such that the cooling start temperature is less than 21 ° C and the end temperature of the cooling is 2 to 6 ° C, so that a fermented food product is obtained.Procedimiento de preparación de un producto alimentario fermentado, incluyendo más de 5·107, en particular más de 108 bifidobacterias por gramo de producto alimentario fermentado durante un período de conservación de al menos 30 días, en particular de al menos 35 días, a partir de un material de partida, que comprende las siguientes etapas sucesivas: - una etapa de siembra de un material de partida, opcionalmente pasteurizado, mediante de inoculación de fermentos de siembra que contienen de 4·106 a 1·107 bifidobacterias por ml de material de partida, para obtener un material sembrado,
