Determination of the change of flavonoid components as the defence materials of Citrus unshiu Marc. fruit peel against Penicillium digitatum by liquid chromatography coupled with tandem mass spectrometry

► Thirteen flavonoids in Citrus unshiu fruit peel were identified for the first time. ► Flavonoids as the defence materials against Penicillium digitatum have been analysed. ► The characterised flavonoids act as defence materials against P. digitatum.