5) Quick post-treatment cooling can be cited can be cited as the fifth feature of differential pressure treatment. To cool treated fruits quickly down to the normal temperature and, if necessary, to a certain cold storage temperature is vital for preserving fruit quality. In the differential pressure system, treated fruits can be cooled down more quickly than other methods by forced circulation of cold air. Furthermore, shower cooling (hydro-cooling) can be done easily by making use of the chimney-type structure.