An apparatus for the heat treatment of a product, especially a food product such as a food product contained within a hermetically sealed container or pouch of plastics or like material, for example for sterilization, pasteurization or cooking, having a heating unit to bring product from ambient towards a heat treatment temperature and pressure； a retort unit to apply a heat treatment to a product； and a cooling unit to allow product to be brought down from heat treatment temperature and pressure towards ambient； wherein each unit and retort is selectably sealable from the others and from ambient conditions.
