Digestibility of β-lactoglobulin following cross-linking by trametes versicolor laccase and apple polyphenols

β-Lactoglobulin (BLG) is an important nutrient of dairy products and an important allergen in cow’s milk allergy. The aim of this study was to investigate the potential of laccase to cross-link BLG in the presence of an apple phenolic extract (APE) and to characterize the obtained products for their digestibility by pepsin and pancreatin. The composition of the apple phenolics used for cross-linking was determined by LC-ESE-MS. The apple phenolic extract contained significant amounts of quercetin glycosides, catechins and chlorogenic acid. The laccase cross-linked BLG in the presence of apple phenolics. The polymerization rendered the protein insoluble in the reaction mixture. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the cross-linking reaction mixture revealed a heterogeneous mixture of high molecular masses (cross-linked BLG), with a fraction of the BLG remaining monomeric. Enzymatic processing of BLG by laccase and apple polyphenols as mediators can decrease the bi-phasal pepsin- pancreatin digestibility of the monomeric and cross-linked protein, thus decreasing its nutritional value. In addition, reduced BLG digestibility can decrease its allergenic potential. Apple polyphenols can find usage in the creation of new, more functional food products, designed to prevent obesity and hypersensitivity-related disorders.