Changes in phenols contents from buckwheat sprouts during growth stage.

Germinated buckwheat is buckwheat seeds soaked in water just until it begins to bud. Buckwheat sprouts are seedling plants of buckwheat grown up to 10-15 cm. The purpose of this study was to determine the optimal growth period for accumulating the most abundant functional phenol(s) in germinated buckwheat that had been soaked in darkness and buckwheat sprouts cultivated by hydroponic culture. The rutin contained in germinated buckwheat was analyzed by CE (capillary electrophoresis). Phenols, including isoorientin, orientin, isovitexin, vitexin, and rutin were separated from buckwheat sprouts by HPLC and identified by LC-MS. The highest rutin content in germinated buckwheat was found to be 15.8 mg/100 g DW at 20 h after germination. Buckwheat sprouts contained five kinds of major phenols. The highest amounts of isoorientin, orientin, isovitexin, and vitexin were measured at day 3, with the exception of rutin, and then a gradual decrease was observed as the sprouts grew. The quantities of isoorientin, orientin, isovitexin, and vitexin at day 3 were 5.8, 11.7, 26.2, and 28.9 mg/100 g FW, respectively. The rutin content rapidly increased to 109.0 mg/100 g FW until day 6. The highest total phenols in buckwheat sprouts were 162.9 mg/100 g FW at day 6. Germinated buckwheat soaked for 20 h and buckwheat sprouts cultivated for 6 days were rich in dietary phenol(s), which makes these plants a valuable functional food for human consumption.