Effects of different phenolic compounds on the interfacial behaviour of casein and the action mechanism

The effects of different phenolic compounds on the interfacial behaviour of casein were investigated, and the action mechanism was further explored. Tannic acid, epigallocatechin gallate, quercetin and quercitrin promoted the aggregation of casein and decreased its solubility. Although the emulsifying and foaming capabilities of casein showed slight decrease with the treatment of phenolic compounds, its emulsifying and foaming stabilities were both greatly improved. By using fluorescence and circular dichroism spectra, phenolic compounds exhibited the capability to bind and form complexes with casein. Meanwhile, the binding interaction by phenolic compounds increased the α-helix content in casein and decreased its random coil content, which indicated a transition of the spatial conformation of casein from disorder to order. By using molecular docking, hydrogen bonds, hydrophobic interactions and Van der Waals were found in the interactions between phenolic compounds and casein. According to the analysis of spectroscopy and simulation results, the structure characteristics of phenolic compounds, including molecular weight, number and position of hydroxyl groups, acylation and glycosylation, exhibited significant effects on their interactions with casein, so as to affect the interfacial behaviour of casein. All present results suggested that phenolic compounds had the potential to improve the properties of casein in food and chemical industries.