Gels stability by improving the hydrophobic region of casein: Effect of the mogrosides on the structure, microstructure, and antioxidant activities in vitro digestive of the casein acid-induced gel

To explore how the stability of gels was improved by the hydrophobic regions of casein, this study investigated the effects of different concentrations of mogrosides on the structure, microstructure, and antioxidant activity of casein acid-induced gels, specifically those induced by gluconic acid delta-lactone. The interactions between mogrosides and the hydrophobic regions of casein were analyzed in terms of conformation and secondary structure, focusing on van der Waals forces, electrostatic interactions, and hydrogen bonds. The average particle size of casein added with 0.7% concentration mogrosides was 268.53 nm at pH = 7, while the average particle size was 229.6 nm at pH = 4.5. The results demonstrated that varying concentrations of mogrosides significantly enhance the stability of casein acid-induced gels. Notably, the gel added with 0.7% mogrosides exhibited excellent rheological properties, microstructure, and antioxidant activities. The 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH) scavenging ability and ABTS content was 62.08% and 85.47% at pH = 7, while the DPPH scavenging ability and ABTS content was 57.91% and 85.87% at pH = 4.5. Microstructural analyses indicated that mogrosides bind closely to casein, substantially influencing its microstructure across different pH levels. Transmission electron microscopy results revealed that mogrosides can regulate the aggregation behavior of casein in the presence of gluconic acid delta-lactone. This study provides a theoretical basis for understanding the mechanism by which mogrosides regulate the aggregation of casein acid-induced gels.