Changes in Bioactive Compounds and Antioxidative Activities of Dehulled Buckwheat Groat Processed by Germination and Roasting

Abstract

This study was conducted to investigate the effects of germination period and degree of roasting on the bioactive compounds and in vitro antioxidant activity of dehulled buckwheat groat. During the 3-day germination period, the amounts of bioactive compounds, including total phenolic and total flavonoid compounds, rutin, and γaminobutyric acid (GABA), increased. This resulted in increased α,α-diphenyl-β-picrylhydrazyl (DPPH), and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities. Germinated buckwheat groats were roasted at 200°C, for 7, 15, and 21 min, and the changes in bioactive compounds were assessed. The total phenolic and flavonoid contents increased at 7 min of roasting but decreased as roasting progressed. An increase in roasting time also led to a decrease in the total flavonoid, rutin and GABA contents. Roasting slightly increased the DPPH radical scavenging activity of germinated buckwheat, but prolonged roasting time (21 min) decreased ABTS radical scavenging activity. Hence, this study suggests that proper processing conditions, such as the correct germination period and degree of roasting should be adopted to improve the amount of bioactive compounds in buckwheat groat for the development of germinated buckwheat tea products. © 2023 The Korean Society of Food Science and Nutrition.