Glycation of β-Lactoglobulin with different lengths sugar chains: Impacts on structure, allergenicity and flavor profile

Abstract

This study aims to perform a comparative study on the structure, allergenicity and flavor profile of β-lactoglobulin (BLG)–galacto-oligosaccharides, maltose, maltotriose and maltopentaose conjugates formed by glycation. Glycation increased BLG's molecular weight, altered the conformational structures and secondary structure from α-helix and β-sheet to β-turn and unordered forms. K47, K83, K91, K135, K138 and K141 of BLG were glycated, destructing the antigen epitopes, leading to reducing the IgE/IgG binding capacity and the release of histamine and interleukin-6 in KU812 cells, with BLG-galacto-oligosaccharides and BLG-maltose showed the lowest allergenicity. Meanwhile, 36 volatile organic compounds (VOCs) were identified in the conjugates, among which 11 were key VOCs, including 2,3-Butanedione and 2-propanol-M, which were the most abundant in BLG-galacto-oligosaccharides and BLG-maltose and positively correlated with glycation levels. Overall, glycation of proteins by different lengths sugar chains influenced the epitope structures and glycation levels, altering allergenicity and the release of flavor compounds.