An apparatus for the heat treatment of a product, in particular a product contained within a hermetically sealed pouch or other plastic container, the apparatus having, a heating unit to contain a product as product is brought towards a treatment temperature and pressure, a sterilization unit to contain product at a pre determined treatment temperature and pressure to sterilize product, and a cooling unit to bring a product from the treatment temperature and pressure towards ambient; each unit being selectively sealable from another unit, the apparatus further having: a plurality of conduits carrying heat-exchange fluids allowing heat to be transferred between units; and having a heater, preferably producing steam, to supply heat to the apparatus; a heat-exchange unit enabling heat energy to be transferred from one conduit to another; and a hot well to retain a reservoir of heat exchange fluid at the highest temperature required by the apparatus.
