Qualities and antioxidant activities of lotus leaf affected by different drying methods

Drying treatments are an effective method for preserving original beneficial ingredients of postharvest plants. This work supplied the suitable drying conditions of three drying methods by investigating the changes of lotus leaves' quality and antioxidant activity. The results indicated that: (1) Oven drying (55-65 degrees C) was the most appropriate way to keep the higher contents of alkaloids and amino acids, and the higher activities in DPPH radical scavenging and hydroxyl radical scavenging in lotus leaf treated with three drying methods; (2) Steam kill-enzyme torrefaction (3-5 min) was the most appropriate method for keeping the higher contents of flavone and the higher activities of superoxide radical scavenging in lotus leaf treated with three drying methods; (3) Microwave drying (680-850 W) was the most appropriate means to keep the higher contents of vitamin C, soluble sugar and protein in lotus leaf treated with three drying methods; (4) The color of lotus leaf treated with microwave treatments was more bright green than that treated with the other two methods; Therefore, the actual conditions of each drying means have to be taken into consideration when use the drying means.