Method for the preparation of gliadin- and glutenin-rich fractions from gluten in an aqueous medium and in the presence of an acid, wherein the gluten are dispersed continuously or not in water up to a dry substance varying between 5 and 30%, by which the pH of the dispersion is monitored between 4.4 and 4.8 and the gluten-water mixture is submitted to shearing actions, through which the dispersion, continuously or not, can be fractionated in gliadin- and glutenin-rich fractions, by which a single gliadin-rich fraction with a gliadin/glutenin ratio of at least 2.5 is obtained, and a single glutenin-rich fraction with a gliadin/glutenin ratio of less than 0.8 is obtained.