Composition of major quinochalcone hydroxysafflor yellow A and anhydrosafflor yellow B is associated with colour of safflower (Carthamus tinctorius) during colour-transition but not with overall antioxidant capacity: A study on 144 cultivars

Yellow pigments in the water-extract of safflower (Carthamus tinctorius L.) belong to quinochalcone flavonoid family and are widely used as food colourants. The aim of the study was to characterize the main quinochalcone compounds in safflower water-extract during blooming period when floret changed colour. Mass-spectrometry results showed that hydroxysafflor yellow A (HSYA) and anhydrosafflor yellow B (AHSYB) were the most abundant. Based on 370 florets samples collected from 144 cultivars, the contents of HSYA and AHSYB were determined, which showed that only AHSYB content had relatively strong positive association with colour indexes. The ratio of HSYA/AHSYB and visual colour exhibited certain patterns: yellow = 2, orange = 3-4, red = more dispersed, mostly falling 5-6. Most of the florets had HSYA increased first and decreased, while AHSYB decreased all the time when floret changed colour as yellow → orange → red. Regardless of the composition of HSYA/AHSYB in florets, the antioxidant capacities of safflower petal water-extracts were the same.