Abstract: Apparatus for rendering material like edible and inedible meat products and blood characterized by a cabinet having at least one and preferably a plurality of elongate paths for traversal of material longitudinally thereof, an endless perforate belt traversing over rollers and along the elongate path for carrying the material therealong in moving bed fashion; the cabinet having walls surrounding the path formed of material that reflects microwave energy and the belt including at least a portion of a material that reflects the microwave energy and coacting with the walls to reflect microwave energy such that multiple passes of the microwave energy through the material is effected for more efficient use. A plurality of microwave energy input stations are employed with the microwave input wave guides being inclined at respective critical angles so as to effect repeated passes of the microwave energy through the material; particularly acute angles .theta. and obtuse angles .beta.