This invention relates to a method and a device for thermally treating flour, especially middlings, for hygienic purposes. The device includes modules which are a first, heatable batch mixer (4) with a pre-mounted depot (1). The batch mixer is connected to a drier/cooler (8) via a lock-like flap system (3). A second batch mixer (12) includes a device (14) for adding additives and a discharge device is mounted behind an additional flap system (11) that is mounted behind the drier/cooler (8).