Impact of Various Drying Technologies on the Drying Characteristics, Physico-chemical Properties, and Antioxidant Capacity of Walnut Green Husk

Walnut green husk (WGH) is a common agricultural by-product with high yield and serious pollution problem. The present study aimed to evaluate the impacts of sun drying (SD), pulsed vacuum drying (PVD), short and medium infrared radiation drying (SMIR), hot air drying based on temperature and humidity control (TH-HAD), and heat pump drying (HPD) on the drying characteristics, energy consumption, physico-chemical properties, bioactive compounds content and antioxidant capacity of WGH. Drying characteristics and drying kinetics showed that artificial drying could significantly improve drying efficiency. Compared with SD, the drying time of PVD, SMIR, TH-HAD, and HPD reduced by 63.6, 78.7, 66.3, and 54.0