Molecular mechanisms of the irradiation-induced accumulation of polyphenols in star anise (Illicium verum Hook. f.)

•Mechanism of irradiation-induced flavonoid accumulation in star anise was explored.•Content of flavonoids in star anise could be increased 2–9 times by irradiation.•The increase of flavonoids was due to the breaking of glycosidic bond.•C15H11O7+ and C3H3O2+ were characteristic fragments of flavonoids.•This work provides a basis for the storage quality of irradiated star anise.