A heat-treatment device for heat treating packaged products that are available in bulk, and to a method of using the device. The device includes: a chamber； a tank for containing a fluid of a density such that the packaged products float when they are poured in bulk into the fluid, the tank presenting an evacuation compartment for evacuating floating products, the evacuation compartment including a hatch that is suitable for being submerged and then opened so as to evacuate a portion of the fluid including the floating products； fluid supply means for filling the tank and for regulating the level of fluid in the tank； submersion means； recovery means； and reception means.
