Spray-freeze-drying systems and methods are disclosed for converting a wide variety of liquid substances into dry powder that may be reconstituted into the original substance by addition of water or other liquid that had been removed therefrom. Such systems and methods involve repetitive cycles of four operational steps, i.e., freezing, drying, defrosting and resetting and are characterized by: spraying the liquid substance downwardly in a vessel while surrounding the spray with a downward flow of process gas during the freezing step and by utilizing a heat pump for energy recapture to increase efficiency of operation.