Apparatus and methods for producing a string of a pasty material, such as sausagemeat. The apparatus includes an extrusion head that includes at least one conveyor conduit for the pasty material to be shaped into a string. The conveyor conduit has an inlet, an outlet, and a receiving chamber for a casing material to be applied to the string. The receiving chamber has an entry for the casing material and an exit for applying the casing material to the string surface. The receiving chamber is also adapted to impart to the casing material, when flowing through the receiving chamber, a movement having at least a rotatory movement component about at least a longitudinal axis of the receiving chamber.