Apparatus and method for inductive heating of a material located in a channel, to modify the state of the material between flowable and nonflowable states. An internal inductive heating assembly is disposed in the material in the channel, and a signal is supplied to the assembly to generate a magnetic flux in at least one of the assembly and the material, the magnetic flux generating inductive heating of the assembly and/or the material. The signal is adjusted to produce a desired rate of temperature cycling of the material in the channel which includes modifying the state of the material between flowable and nonflowable states. In one embodiment, the heating assembly includes an interior coil, an exterior sheath inductively coupled to the coil, a dielectric material disposed between the coil and sheath, a flux concentrator, and a conductor for supplying a signal to the coil to generate the magnetic flux. The materials and/or Curie temperatures of the coil, sheath and/or flux concentrator may be selected to provide a desired rate of inductive heating of the sheath and/or the material.