The most common fresh fruit bunch (FFB) sterilisation system used in a palm oil mill is still the conventional horizontal type. In this system, a few cages are filled with (FFB) and pushed into each steriliser which is actually unfired pressure vessels. Steam at 3 barg is admitted to the FFB laden cages for a period of 90 minutes. The first 10 min were for de-aeration during which the air contained in the steriliser chamber is driven out during the scheduled three blow-off cycles.