Study on zinc ions binding to the individual casein fractions: α-, β- and κ-casein

•Influence of zinc ions concentration on the αS1 -, β -, κ -casein structure.•Physicochemical properties of Zn-casein complexes.•Mechanism of metal-protein binding and of ZnCN metallocomplexes formation.•Zeta potential measurements to determine the stability of the casein fractions.•Identifications of precise binding sites using the molecular docking.