Change in conformational, digestive and immunological characteristics of bovine allergen β-lactoglobulin induced by metal ions in combination with heating

•Heat treatment and divalent cations had impact on the aggregation of β-lactoglobulin.•Ca2+ and Zn2+ increased the particle size of β-lactoglobulin aggregates.•Cu2+ effected the conformational structure of β-lactoglobulin strongly.•Free sulfhydryl content was significantly declined after Cu2+ treatment.•Cu2+ enhanced peptic digestion of β-lactoglobulin and decreased its antigenicity. Aggregation of bovine β-lactoglobulin is affected easily by external factors. In this study, effects of metal ions combining with temperature on aggregation of β-lactoglobulin were explored. The conformational characteristics of aggregates were detected by environment scanning electron microscope, CD spectrum and free sulfhydryl group, respectively. Digestive and immunological characteristics were assessed by simulated digestion in vitro and ELISA respectively. The results showed that the morphology of β-lactoglobulin aggregates became more amorphous in Cu2+ and Mg2+ treated samples and more constricted in Zu2+-induced protein. Among them, Cu2+ altered the secondary structure of β-lactoglobulin aggregates and free sulfhydryl content most as well as that in gastric digestion. However, all ion-treated groups had similar digestive stability in intestinal digestion. Specially, Ca2+ and Mg2+ made the antigenicity and potential allergenicity of β-lactoglobulin aggregates decrease, which helps us understand the role of metal ions in immunological characteristics.