Phenolics levels in different parts of common buckwheat (Fagopyrwn esculentum) achenes

Common buckwheat achenes have high antioxidant activity due to their high phenol and especially flavonoid content. In general, the highest phenol contents in seeds is related to the seed coat layers. However, there is insufficient information about the composition of the individual parts of the buckwheat achene. The aim of this study was to determine the distribution and content of selected phenols within the individual parts of buckwheat achenes as well as the influence of soaking before hulling had on the phenol content. The seed coat was the part with the widest range of detected compounds, and also with the highest total content of phenolics from all groat parts. The seed coat was especially rich in epicatechin (257.60 mg/kg), procyanidin B2 (118.6 mg/kg), and epicatechin gallate (61.27 mg/kg). The embryo axis with the cotyledons is rich in rutin (283.37 mg/kg) and catechin (161.41 mg/kg). Contrary to groats, vanillic acid, vanillin, vitexin, quercitrin, and protocatechuic acid were detected in the buckwheat hulls. One-hour soaking of the achenes in tap water before dehulling caused a significant decrease (37%) in the content of phenolic compounds. The variety Spacinska had the highest level of identified phenolic compounds in the buckwheat hulls.