The present invention relates to thermally inhibited starch and starchy flours produced by heat treatment of native starch that is pre-dried where necessary to a dry matter content of more than or equal to 95% by weight, preferably 98% by weight, particularly preferably 99% by weight, wherein said starch, pre-dried where necessary, is heat treated in the presence of at least 0.1 percent by volume of oxygen at a product temperature in excess of 100° C. in a vibrating spiral conveyor.