A study of functional components antioxidant activity and sensory characteristics of Gastrodiae Rhizoma by steaming-drying cycles

Objectives : The objective of this study is to determine the best numbers of steaming-drying cycles of Gastrodiae Rhizoma for both efficacy and taste. We investigated various characteristics among Gastrodiae Rhizoma samples (GSD1, GSD3, GSD5 and GSD7) through the number of steaming-drying cycles increased. Methods : Gastrodiae Rhizoma were steamed and dried at different repeated numbers. They were divided into samples (GSD1; steamed and dried once, GSD3; steamed and dried three times, GSD5; steamed and dried five times, GSD7; steamed and dried seven times) for experiment. They were extracted using water, freeze dried and powdered to analyze proximate composition, free sugar amount, functional components, antioxidant activity and sensory evaluation. Results : Proximate composition and the amount of free sugars of Gastrodiae Rhizoma did not have meaningful differences among samples. Phenolic and flavonoid content of samples were increased by increasing steaming-drying numbers. Gastrodin content had different values and GSD7 was the highest in comparison with others. Increasing steaming-drying numbers led to a increasing in radical and nitrate scavenging activity in samples. Regarding to sensory evaluation, GSD5 was selected as the best sample according to its highest hedonic score mean (5.54/7) among all samples for appearance, color, taste and overall acceptability. Conclusions : The results indicated that 5th-cycling sample was effective in views of functional components, antioxidant activity and sensory characteristics. Moreover, it was suggested that steaming-drying process improved remarkably the effects of Gastrodiae Rhizoma.