Effect of glycation on the gastrointestinal digestibility and immunoreactivity of bovine β-lactoglobulin

Immunoreactivity of bovine β-lactoglobulin (β-Lg) hydrolysates obtained after a simulated gastrointestinal digestion and previously glycated via Maillard reaction with galactose, tagatose, and dextran of 10 or 20 kDa has been determined, with a view to study the effect of glycation and aggregation degree of β-Lg on its residual immunoreactivity. High levels of glycation impaired β-Lg proteolysis and, consequently, increased the IgG- and IgE-reactivities of hydrolysates, regardless of the carbohydrate used. Protein aggregation during the advanced stages of Maillard reaction had a masking effect on β-Lg epitopes, counteracting the negative effect of the lower digestibility of glycated protein on its allergenicity. Finally, the use of polysaccharides as glycation agents did not contribute to enhancement of the masking effect of the attached carbohydrate on β-Lg epitopes. These findings stress the importance of evaluating the impact of glycation on protein gastrointestinal digestibility prior to investigation of the immunoreactivity of protein Maillard complexes.