A comparison among β-caseins purified from milk of different species: Self assembling behaviour and immunogenicity potential

Caseins are a family of proteins constituted by α-caseins (αs-1 and αs-2 caseins), β-caseins and κ-caseins. β-caseins, in particular, show a temperature and concentration-dependent self-assembling behaviour. Recently, β-casein micelles have been proposed as natural nanocarriers for the delivery of hydrophobic compounds, promoting their bioavailability. Until now, all studies regarding both chemical-physical characterization and applications of β-caseins have employed the protein of bovine origin. However, it could be interesting to exploit the use of β-caseins from other milk sources for their potential encapsulation ability and immunogenicity but, at present, no information on the self-assembling behaviour is available for β-caseins from the milk of species different from bovine. In this work, for the first time, β-caseins from human milk and from donkey, goat, and sheep milk were purified and their self-assembling behaviour was compared to that of a commercial bovine β-casein, the only one for which the concentration and temperature aggregation behaviour is known. Furthermore, a preliminary evaluation of the immunogenicity potential of β-casein from other milk sources has been performed by cross-reaction experiments using anti-β-casein antibodies from bovine origin. The results indicated a similar self-assembling profile among all β-caseins examined compared to the bovine β-casein, suggesting the possible use of β-casein from other milk sources as nanocarriers. Since donkey and human β-casein do not cross-react with bovine anti-β-casein antibodies, they could be particularly interesting for the development of self-assembling systems with lower hypoallergenic potential.