Structure and allergenicity assessments of bovine beta-lactoglobulin treated by sonication-assisted irradiation

Bovine beta-lactoglobulin (beta-LG) is recognized as a major allergen in milk. This study aimed to investigate ultrasound-assisted irradiation for reducing the allergenicity of beta-LG, since irradiation can reduce the allergenicity of cow milk proteins and ultrasound can improve the quality of milk. The structural changes induced in high purity beta-LG, treated by irradiation, with or without sonication, were characterized by native PAGE, circular dichroism spectroscopy, and fluorescence spectroscopy. The changes in allergenicity were measured by IgE binding capacity to, and inflammatory mediator secretion by, human basophil KU812 cells. Surface hydrophobicity was reduced and aggregation of beta-LG increased after treatment by irradiation, both with and without sonication. The IgE binding capacity and release of inflammatory mediators were reduced significantly and the reduction induced by irradiation before sonication was the greatest, suggesting that irradiation after sonication can be a safe and effective method to reduce the allergenicity of beta-LG in dairy processing.