Characterization and in vitro digestibility of bovine β-lactoglobulin glycated with galactooligosaccharides

摘要

Galactooligosaccharides (GOS) are well-known prebiotic ingredients which can form the basis of new functional dairy products. In this work, the production and characterization of glycated β-lactoglobulin (β-LG) with prebiotic GOS through the Maillard reaction under controlled conditions (aw = 0.44, 40°C for 23 days) have been studied. The extent of glycation of β-LG was evaluated by formation of furosine which progressively increased with storage for up to 16 days, suggesting that the formation of Amadori compounds prevailed over their degradation. RP-HPLC-UV, SDS-PAGE, and IEF profiles of β-LG were modified as a consequence of its glycation. MALDI-ToF mass spectra of glycated β-LG showed an increase of up to ∼21% in its average molecular mass after storage for 23 days. Moreover, a decrease in unconjugated GOS (one tri-, two tetra-, and one pentasaccharide) was observed by HPAEC-PAD upon glycation. These results were confirmed by ESI MS. The stability of the glycated β-LG to in vitro simulated gastrointestinal digestion was also described and compared with that of the unglycated protein. The yield of digestion products of glycated β-LG was lower than that observed for the unglycated protein. The conjugation of prebiotic carbohydrates to stable proteins and peptides could open new routes of research in the study of functional ingredients.