Enhanced physicochemical stabilities of cyanidin-3-O-glucoside via combination with silk fibroin peptide

Applications of cyanidin-3-O-glucoside (C3G) are limited due to the poor stabilities. In this work, we proposed using silk fibroin peptide (SFP) to bind with C3G and form nanocomposites (134.73 ± 4.51 nm) for stabilization. When interacted with C3G, the fluorescence of SFP contributed by tyrosine and phenylalanine amino acids was quenched, which was proved a static quenching with the β-sheet structure of SFP unchanged. With the further exploration of the physicochemical stabilities of C3G in the nanocomposites, we demonstrated that the tolerance of C3G to the alkaline environment and the retention ratio of C3G in various concentrations of metallic ion Cu²⁺ were significantly improved. In addition, the heat resistance of C3G in SFP at 80 °C was also enhanced with up to an increase of 2.5 times for the average half-life of C3G. Our results shed light on SFP could enhance physicochemical stabilities of C3G with maintaining its antioxidant activity.