Determination of fagopyrins, rutin, and quercetin in Tartary buckwheat products

Buckwheat grain is a valuable source of various phytochemicals: health promoting flavonoids (rutin), as well as substances such as phototoxic fagopyrin. In this study, total fagopyrins, rutin, and quercetin were determined in Tartary buckwheat grains, milled fractions, and food products. HPLC was used for analyses; fagopyrins were detected by fluorescence, flavonoids by UV/VIS. After steaming, the fagopyrin content in the grain decreased. The remaining fagopyrins were unequally distributed; minor amounts were found in groats and higher concentration in hulls. Similarly, the concentration of rutin decreased, although to a lesser extent. Unlike fagopyrins, rutin was concentrated in groats. In the bread making procedure, a minor decrease of fagopyrins was seen comparing its concentration in grains, dough, and bread, while large amounts of rutin were degraded into quercetin during baking. Our results may stimulate further research on edible parts and products of buckwheat, particularly, the quantitative evaluation of total fagopyrin content in relation to flavonoids, providing information about the treatment process needed to prepare buckwheat products with the highest utilization value.