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Background : Rehmannia glutinosa root has been commonly used as traditional medicine in Korea. This root including prepared rehmannia that is the steamed root of rehmannia can be also used as food. This study was performed to analyze the quality properties of the root and the tea with different steaming conditions to evaluate the potential as a tea.
Methods and Results : For this study, we used ‘Dagang’, new variety of R. glutinosa, developed by NIHHS. The root was dried and steamed for 9 times. Every steaming, powder and extract were used for pH, antioxidant activity analysis (total phenolic acid and total flavonoid content) and sensory evaluation. As steaming repeated, pH was decreased. The total phenolic acid and total flavonoid content was increased during steaming process. In the sensory evaluation for the tea, 56% of respondents (A group) recognized the difference between 6th and 9th steaming tea correctly but 44% (B group) didn’t. The sensory scores showed that 6th and 7th steaming tea had higher overall preference scores than other samples. This tendency was more clear in the A group. Depending on the age group, there were significant different tendency among 3 age groups (20 – 30 s, 40 – 50 s, over 60 s). The youngest group was preferred 6th than 9th steaming tea. On the other hands, 9th steaming tea had more priority than 6th steaming tea in older age group.
Conclusion : This study showed a potential of R. root as a tea material. The quality properties of the R. root are affected by steaming conditions and the preference tendency of tea was different depending on the age group. These data can be used to develop tea material suitable for consumer age and establish optimal steaming conditions in industrial use.
