Investigation into allergenicity reduction and glycation sites of glycated β-lactoglobulin with ultrasound pretreatment by high-resolution mass spectrometry

Ultrasound treatment could change the conformation of beta-lactoglobulin (beta-Lg) and improve the glycation reaction in aqueous solution under neutral condition. However, the effect of ultrasound pretreatment on glycation of beta-Lg with pentose at dry-state remains ambiguous, and the relationship between glycation and allergenicity of beta-Lg with ultrasound pretreatment is unclear. This study aimed to evaluate the effect of ultrasound pretreatment on glycation and allergenicity of beta-Lg. Markedly decreased allergenicity of beta-Lg was observed after glycation with ribose before and after ultrasound pretreatment with the minimum found at 400 W. Orbitrap LC-MS/ MS showed that the glycation degree of some peptides in glycated beta-Lg with and without ultrasound pretreatment were different although the content of free amino group and molecular mass were insignificantly different. Therefore, ultrasound pretreatment promoted the reduction in allergenicity by improving the glycation extent of some glycation sites although it hardly enhanced the whole glycation degree of beta-Lg.