The present invention relates to a process for preparing modified potato flakes or modified potato granules, comprising the steps of: a) washing potatoes; b) removing the peel and any impurities where applicable; c) optionally cutting the potatoes up; d) optionally blanching the potatoes; e) optionally cooling the potatoes if step d) is performed; f) cooking the potatoes under steam; g) sieving or pulping the potatoes cooked under steam; h) optionally adding additives other than fibrous materials; and i) drying the pulp obtained, wherein, after step b) and before step i), fibrous materials are added in at least one further step and are mixed substantially homogeneously into a product of the process as present at the time when they are added; modified potato flakes or potato granules prepared in accordance with said process, and their use.