A treatment device (10) for treating food products with conditioned air comprises a housing (12) with a product inlet (20) and product outlet (22), which housing (12) defines a treatment chamber (26, 28). The device (10) comprises at least one conveyor means (24) for conveying the products through the treatment chamber from the product inlet to the product outlet, air-circulation means (44, 46) for causing an air stream to flow through the treatment chamber, and air-conditioning means (36, 38) for conditioning the air stream, which air-conditioning means at least comprise heating means (36) and moisture-feed means (38). The treatment device is also provided with controllable air-discharge means (48, 50) for discharging air from the treatment chamber, and with a control device for controlling the moisture content of the conditioned air in the treatment chamber to within a range defined by a predetermined lower limit and upper limit