Physicochemical stability-increasing effects of anthocyanin via a co-assembly approach with an amphiphilic peptide.

To enhance the stability of anthocyanin, an amphiphilic peptide C6 with tryptophan amino acid was used to co-assemble with anthocyanin C3G. The characterization, stabilities, and antioxidant activity of peptide-anthocyanin (C6-C3G) nanocomposites (70.82 ± 12.41 nm) were investigated. To illustrate the interaction between peptide and anthocyanin, circular dichroism spectroscopy and fluorescence quenching method were used. Here, the peptide C6 switches from random coil structure to β-sheet structure and the fluorescence of tryptophan amino acid in peptide quenched during the intermolecular interaction between them, which was further confirmed a static quenching. The nanocomposites significantly enhance the stabilities of anthocyanin to different alkaline conditions, high temperature of 80 °C, long time storage, and various concentration of Cu2+ ion. In addition, it maintained the excellent intrinsic capacity of anthocyanin to scavenge free radicals. The approach of using an amphiphilic peptide to enhance the stabilities of anthocyanin presents a high potential to expand its application.