A sealing jaw for producing sealed packages of a food product from a tube of packaging material fed along a path, the jaw having a first work surface which interacts with a second work surface on a counter-jaw to grip the packaging material and form a sealing strip crosswise to the path. One of the jaw and counter-jaw defines an anvil, and the other defines a heating device which interacts with the anvil to form the strip. The first surface has at least two projections elongated along respective first axes, and which, when forming the strip, compress respective areas of the packaging material against the second surface; and at least one cavity which extends along one of the first axes, is interposed between the projections along a second axis crosswise to the first axis, and is located laterally with respect to a central plane of the first work surface.