Study on Drying Technology of Phyllanthi Fructus by Microwave Hydrodiffusion and Gravity

Phyllanthi Fructus was dried using microwave hydrodiffusion and gravity (MHG). The effects of microwave irradiation power (210, 350, 560, and 700 W) and irradiation time (5～23 min) on the moisture content of Phyllanthi Fructus and the leachate volume were investigated. The total phenolic content of the phenol-rich juice obtained during drying was also determined. The results showed that under the condition of 560 W irradiation for 7 minutes, the obtained leachate had the highest total phenolic content, reaching 125.37±5.67 mg GAE/mL, the largest leachate volume (27 mL/50 g FW), and the lowest moisture content of Phyllanthi Fructus (28.92%); subsequently, further drying in a traditional oven for 2 hours reduced the moisture content to below 13%. Gallic acid was quantified by HPLC, and the leachate was analyzed by UPLC-MS, confirming the retention and enrichment of tannins, flavonoid glycosides and other antioxidants.MHG is a green and efficient technique that can significantly shorten the drying cycle and improve drying efficiency.