A New Fluorescence Band of Anthocyanins as a Simple Oxidation Biomarker of Food Products

The formation of a new fluorescence band of anthocyanidins and anthocyanidins, centered at about 530 nm (excitation at 460-470 nm), is proposed as a simple indicator of food oxidation. This fluorescence band appeared and increased progressively during the incubation of blueberry juice under aerobic conditions and the cooking of blueberry homogenate and black carrot. The same effect was observed upon the addition of delphinidin to rapeseed oil subjected to simulated frying. A ratiometric parameter (ratio of the fluorescence intensity at the maximum of the new band to the fluorescence intensity of native anthocyanins/anthocyanidin) is proposed as a versatile index useful for the estimation of the oxidation of food products containing anthocyanins or supplemented with anthocyanins or anthocyanidins.