Thermal denaturation of bovine β-lactoglobulin in different protein mixtures in relation to antigenicity

Denaturation of β-lactoglobulin (BLG) was studied in relation to its antigenicity at two heat treatments in several native protein mixtures; allergenicity was determined by enzyme-linked immunosorbent assay based on BLG capacity to bind with immunoglobulin G (IgG) antibodies. The influence of other proteins on BLG denaturation correlated with altered antigenicity. Treatment at 72 °C/15 s enhanced antigenicity in a BLG+α-lactalbumin (ALA) mixture, possibly due to exposed epitopes in the unfolded structure. Treatment at 100 °C/30 s mostly resulted in BLG-led protein aggregation through thiol/disulphide interactions and decreased antigenicity by fragmentation and masking of epitopes, the extent of which was mixture-dependent. The presence of IgG resulted in diminished antigenicity in BLG + ALA + IgG at 100 °C/30 s in comparison with BLG + ALA. ALA governed whey protein denaturation over BLG in BLG + ALA + IgG + bovine serum albumin (BSA), possibly catalysed by BSA at 100 °C/30 s, resulting in a higher retention of antigenicity than in other mixtures.