Physicochemical, phytochemical and antioxidant properties of medicinal plant roots Dan sam ( <i>Salvia miltiorrhiza</i> Bunge) prepared under different drying conditions

Dan sam (Salvia miltiorrhiza Bunge) root is widely used in folk medicine for the prevention and treatment of various chronic ailments. This study aimed to assess the influence of different drying conditions on the physicochemical properties (drying yield, drying time, energy consumption, residual moisture, water activity, color, and structure), phytochemical content (total saponin content: TSC, total phenolic content: TPC, total flavonoid content: TFC, and total alkaloid content: TAC), and antioxidant capacity (ABTS radical scavenging capacity: ARSC, DPPH radical scavenging capacity: DRSC, and Ferric reducing antioxidant power: FRAP) of Dan sam root. The findings showed that all drying conditions could reduce the water activity to safe storage values. Freeze drying (FRD) possessed the greatest TSC (33.66 mg escin equivalents (EE)/g DW) and TPC (16.68 mg gallic acid equivalents (GAE)/g DW), while microwave drying at 720 W (MWD720) also achieved high levels in TSC (32.00 mg EE/g DW), TAC (13.16 mg atropine equivalents (AE)/g DW), and TFC (1.26 mg catechin equivalents (CC)/g DW). In addition, FRD possessed the highest ARSC, DRSC, and FRAP values, followed by MWD720. However, FRD consumed the most drying time and energy. In contrast, MWD720 had the shortest drying time and the lowest energy consumption. Therefore, MWD720 was recommended for preparing dried Dan sam roots for further investigation and utilization.