Combined ⁶⁰Co-γ and Electron-Beam Irradiation Enhances Flavonoid Extraction and Antibacterial Activity in Tartary...

Extraction of Tartary buckwheat flavonoids (TBFs) is often limited by the dense lignocellulosic cell wall matrix. To address this, the effects of ⁶⁰Co-γ rays (γSI), electron beams (EBI), microwaves (WI), and their combinations on flavonoid extractability and bioactivity were evaluated. Among the tested conditions, γSI + EBI (6 + 6 kGy) produced the highest flavonoid yield (7.43%), representing a 135.9% increase over the control and exceeding the yields of the single-source treatments at the same total dose. HPLC and LC-MS profiling revealed that the combined irradiation markedly elevated the release of key monomers-particularly rutin (increased by 93.2% to 97.77 mg/g)-without degrading the core flavonoid skeleton. SEM and FT-IR analyses suggested that the improved extraction was associated with increased surface disruption and matrix-related structural modification. Furthermore, the resulting extracts also showed enhanced antibacterial potential, with inhibition zones against Escherichia coli and Staphylococcus aureus reaching 14.6 and 15.8 mm, respectively. This study demonstrates that combined irradiation is a highly effective, scalable technology for valorizing Tartary buckwheat byproducts into high-value functional ingredients. PRACTICAL APPLICATIONS: Tartary buckwheat bran (TBB) is a nutrient-rich byproduct of grain processing that is often underutilized. This study evaluates a combined pretreatment strategy using γSI and EBI irradiation to improve the extraction efficiency of bioactive flavonoids from TBB. The treatment increased the yield of high-value compounds such as rutin and enhanced the antibacterial potential of the resulting extracts. These findings provide a proof-of-concept basis for future development of irradiation-assisted pretreatment strategies to valorize TBB.