The invention relates to a full-automatic sterilizing quality-guaranteeing steamer and a sterilizing technology which are suitable for sterilizing and quality guaranteeing of fully closed box-packed fast food. The steamer comprises a pot body, a pot cover, a steam
pipe, a return
water storage tank, a vent
pipe, a
water cycle pipeline and a drain
pipe, wherein the
water cycle pipeline comprises a return
water pipe, a chief spray pipe, a water inlet pipe and a water outlet pipe, the pot body is provided with a
thermometer I, a pressure gauge I, a water-
thermometer I and a reducing valve I, and is connected with an
automatic control box, the pot cover is hermetically connected with the pot body, the pot body is connected with the steam pipe, the vent pipe, the chief spray pipe and the water outlet pipe, the return
water storage tank is connected with the return
water pipe and the vent pipe, the drain pipe is communicated with the water outlet pipe, the inner cavity of the pot body comprises a
temperature control sensor, a water outlet hole, a
steam heating pipe, an upper spray pipe and a side spray pipe, and the upper spray pipe and the side spray pipe are communicated with the chief spray pipe. The steamer can be used for automatically and accurately controlling the temperature, pressure and time, guaranteeing the sterilizing quality through heating and cooling by gradient, and saving energy and water because the hot and cold spray water is used and stored reasonably.