Microencapsulated mulberry anthocyanins promote the in vitro-digestibility of whey proteins in glycated energy-ball models

The effects of mulberry anthocyanins (MAs) on the digestibility of whey proteins (WP) in freshly-prepared and stored energy balls were studied. Results showed that MAs increased digestibility of the energy balls by increasing their hydrolysis-degree, soluble peptides-fractions, and decreasing their particle's size and agglomeration. To understand the mechanism of the promoting and/or inhibiting digestive effects of MAs, secondary structure alterations and binding of WP-MAs-mixtures were therefore measured. Results revealed that MAs could noncovalently/covalently interact with WP and form WP-MAs-adducts. This interaction seemed to be responsible for the alterations in the secondary structure of WP which could promote the digestibility of the energy balls subsequently. MAs also partially unfolded the structure of digested-WP through fluctuating their α-helix and β-sheet. It was concluded that the unfolding in WP-structure induced by MAs-interactions might increase accessibility of the peptide bonds to the digestive enzymes and consequentially facilitate the protein's digestibility in the energy balls.