Structural and surface properties of whey protein from buffalo milk as influenced by exopolysaccharide

Abstract

The influence of exopolysaccharide (EPS) on the structure of whey protein (WP) molecules at different pH and ionic strengths was investigated using fluorescence and circular dichroism (CD) spectroscopy. The WPs were separated using 0.2 mol/L glacial acetic acid, which has been proved to maintain to the maximum extent the native structure of WP molecules. The interaction between WP and EPS was significantly influenced by the ionic strength and pH. The presence of NaCl reduced the repulsion and aggregation of WP at pH 7.0. The addition of EPS increased the β-sheet structure of WP and this change tends to disappear at high ionic strength (0.3 mol/L). On the other hand, the repulsive interaction between WP and EPS at pH 7.0 and 6.0 has minimal influence on tryptophan (Trp) quenching and the exposure of hydrophobic residues to the hydrophilic environment. The formation of WP/EPS complexes at pH 5.0 led to the increased exposure of the Trp group to the hydrophilic phase. Both the electrostatic repulsion and attraction increased the secondary structure of WP at all pH values tested in this research. ARTICLE HISTORY

Usage of in situ exopolysaccharide‐forming lactic acid bacteria in food production: Meat products—A new field of application?

“…As such, the formation of EPS occurring in situ in the matrix may cause similar phase separations once the EPS concentration reaches a critical value. These phenomena depend not only on polymer concentration, but on structural properties, and occur, for example, more readily if polymers have high molecular weights, carry high similar charges, and differ in flexibility and ability to assume different configurations (Zhao, Li, Zhao, & Li, 2017). Studies have shown segregative phase separation phenomenon can be a major contributor to a soft texture and spreadability, since network forming polymers (e.g., proteins) are hindered in their ability to crosslink and form percolating structures.…”