Abstract: A method for treating material comprising starch and starch-bearing products wherein the products are introduced to a thermal processor comprising a housing defining an inner wall surface, an inlet end, an outlet end, and an agitator rotatable within the housing adapted to direct the material into contact with the inner wall surface. The inner wall surface is heated and nozzles associated with the agitator are used for discharging fluid from the nozzles into contact with the material during rotation of the agitator. Heating to obtain treatment of the material is provided by contact with the inner wall surface and by controlling the fluid discharge from the nozzles to create turbulence for spreading the material over a broad surface area of the inner wall surface to enhance and render substantially uniform the heat exchange between the material, the fluid, and the inner wall surface, and to control mass transfer between the fluid and the material.