was freeze dried using freeze dryer equipment (Labconco 2.5 L). For spray freeze drying, an aqueous CNC suspension was sprayed into a container containing liquid nitrogen, equipped with a magnetic stirring bar, and then transferred to the freeze dryer equipment (Labconco 2.5 L). The frozen suspension was lyophilized at −52 °C and 0.05 mbar for a period of time (24–72 h).