A method for treating items as the items move along a trough, such as for freezing, drying, or baking food items, includes the steps of placing an item to be treated in an inlet end portion of a trough having sides, a top, and a perforated bottom, the perforations making up between about 0.5% and about 20% of the bottom of the trough. A treating gas is forced through the perforated bottom at a velocity through the perforations and a volume sufficient to elevate and float the item above the bottom of the trough. The item moves along the trough, such as by gravity in an inclined trough or by action of the treating gas against the item, as the treating gas flows against the bottom, around the sides, and over the top of the item to treat the item. The item is left in the trough for a period of time sufficient to complete the desired treatment. Upon completion of treatment, the item is removed from an outlet end portion of the trough after the item has moved from the inlet end portion of the trough to the outlet end portion of the trough and completion of the desired treatment.