Effect of the Steaming Process on Quality of Postharvest Cistanche deserticola for Medicinal Use during Sun Drying

Effect of steaming on postharvest stems of Cistanche deserticola Y. C. MA was evaluated periodically during sun drying in both years. Steamed stems exhibited oily black in color, slightly heavier and longer than untreated ones. The levels of five phenylethanoid glycosides and 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) scavenging activity in steamed stems remained relatively stable during sun drying. Steamed samples showed higher amounts of water-soluble extracts, dilute ethanol-soluble extracts, soluble sugars, and polysaccharides, while a lower level of total ashes than untreated samples. The overall results suggest that steaming is an effective processing for enhancing the appearance quality and the concentration of some bioactive compounds in Cistanches Herba.