The object of the process of the invention is to increase the retention of starch in the sheet of paper in order to reduce operating costs and increase the physical characteristics of the paper. To that end, it has been envisaged that trivalent cationic salts are added, metered into the slurry or in the process for obtaining starch in powder form or by mixing a percentage of trivalent salts in powder form with the starch in powder form, seeking the solution of said salts in the slurry, so that they dissolve during the dispersion of the slurry in the process for obtaining the sheet of paper. Organic polymers such as polyacrylamides, polyvinylamides and polydadmacs could optionally be applied in addition to said salts.