Monitoring the Interaction Between Thermally-Induced Whey Protein and Anthocyanin

Our goal was to investigate anthocyanin binding to native and preheated whey protein using fluorescence quenching spectroscopy. Whey protein were preheated from 40-80℃ for 30 minutes, then mixed with various concentrations of anthocyanins (0~100 #M). Fluorescence spectra was recorded from 360-450nm at 25, 35, 45℃ with excitation at 280nm. All anthocyanins strongly quenched whey protein’s fluorescence. The fluorescence intensity of whey protein decreased 68%-73% and its max increased (372-378nm) as anthocyanin concentration increased. The anthocyaninwhey protein quenching was determined to be static with only one binding side on the whey protein interacting with anthocyanins. Thermodynamic analysis showed that the binding between anthocyanin and whey protein was mainly through hydrophobic interaction. The binding affinity was higher for preheated whey protein and decreased gradually with increasing temperature due to whey protein aggregation. These results help better understand the protection mechanism of native or preheated whey protein on anthocyanin color stability, widening the application of anthocyanins as food colorants in food processing and storage.