Buckwheat grain phenolics: Composition, bioactivity, and processing

Buckwheat (Fagopyrum spp.) is a gluten-free pseudocereal rich in phenolic compounds, yet reported profiles and bioactivities remain inconsistent across studies. This review critically synthesized recent evidence on phenolic composition in buckwheat grain matrices (husk/bran, groats/flour, and sprouts), emphasizing soluble free, soluble-bound, and insoluble-bound fractions and how analytical methods led to variability. Species- and tissue-dependent differences, particularly between common and Tartary buckwheat, and the limited data for underutilized Fagopyrum species were highlighted. Processing was treated as a primary determinant of phenolic fate: Germination/sprouting and fermentation can increase extractability and reshape profiles; thermal and physical operations (e.g., steaming/roasting, extrusion, ultrafine grinding) can either release bound phenolics or promote degradation and matrix binding. A key issue was the control of rutin-quercetin conversion, which affected both sensory properties and bioaccessibility. Knowledge gaps and priorities for standardization and food design were identified.