A flexible heat exchange jacket is provided which has channels for flow of
a heat exchange fluid along one side, with inlets and outlets attached to
a source of heat exchange fluid. The jacket can be attached in a
watertight manner around the circumference of a cylindrical process
container containing a liquid for heat treatment. Preferred embodiments
include devices for heating and/or cooling the heat exchange fluid prior
to entering the jacket, mixers for the liquid under treatment within the
container, and heaters for the liquid within the container and/or the
bottom of the container itself. A dairy pasteurizer version combines a
cylindrical process container with a heat exchange jacket installed
around its exterior with heating and refrigeration units for the heat
exchange fluid, heat sensing and mixing devices, and a control system
programmed to execute a pasteurization cycle.