关键词: 秋葵, 热风干燥, 真空冷冻干燥, 理化特性, 抗氧化活性

Abstract: The effect of different drying methods (i.e., hot-air and vacuum freeze drying) on the physicochemical properties and antioxidant activity of okra superfine powder was studied. The results showed significant differences in physical properties (solubility, water holding capacity and bulk density), VC content, chlorophyll content and antioxidant activity between hot-air and vacuum freeze dried samples (P < 0.05). Compared with hot-air dried sample, vacuum freeze dried sample had lower water holding capacity and bulk density, and higher solubility and VC contents and its methanolic extract exhibited stronger antioxidant activity in scavenging 1,1-diphenyl-2-picrylhydrazyl and superoxide anion radicals. There were significant differences in all physicochemical properties except water holding capacity and bulk density among vacuum freeze dried samples of four cultivars four varieties (P < 0.05). The superfine powder of the cultivar Meng 1 had the highest solubility, VC content and antioxidant activity. The superfine powder of vacuum freeze dried okra was superior to its hot-air dried counterpart in terms of physical properties, VC content and antioxidant activity, indicating that vacuum freeze drying was more suitable for the production of superfine powder of okra especially Meng 1, which had higher market value.

Key words: okra, hot-air drying, vacuum freeze drying, physicochemical properties, antioxidant activity