Insight into the Stabilization Mechanism of Succinylation Modification on Black Bean Protein Gels: Molecular Conformation, Microstructure, and Gel Properties.

The objective of this work was to investigate the effect of succinylation treatment on the physicochemical properties of black bean proteins (BBPI), and the relationship mechanism between BBPI structure and gel properties was further analyzed. The results demonstrated that the covalent formation of higher-molecular-weight complexes with BBPI could be achieved by succinic anhydride (SA). With the addition of SA at 10% (v/v), the acylation of proteins amounted to 92.53 ± 1.10%, at which point there was a minimized particle size of the system (300.90 ± 9.57 nm). Meanwhile, the protein structure was stretched with an irregular curl content of 34.30% and the greatest processable flexibility (0.381 ± 0.004). The dense three-dimensional mesh structure of the hydrogel as revealed by scanning electron microscopy was the fundamental prerequisite for the ability to resist external extrusion. The thermally induced hydrogels of acylated proteins with 10% (v/v) addition of SA showed excellent gel elastic behavior (1.44 ± 0.002 nm) and support capacity. Correlation analysis showed that the hydrogel strength and stability of hydrogels were closely related to the changes in protein conformation. This study provides theoretical guidance for the discovery of flexible proteins and their application in hydrogels.

Formation mechanism of quinoa protein hydrolysate-EGCG complexes at different pH conditions and its effect on the protein hydrolysate-lipid co-oxidation in emulsions.

This study aimed to investigate the interaction, structure, antioxidant, and emulsification properties of quinoa protein hydrolysate (QPH) complexes formed with (-)-epigallocatechin gallate (EGCG) at pH 3.0 and 7.0. Additionally, the effect of pH conditions and EGCG complexation on protein hydrolysate-lipid co-oxidation in QPH emulsions was explored. The results indicated that QPH primarily interacted with EGCG through hydrophobic interactions and hydrogen bonds. This interaction led to alterations in the secondary structure of QPH, as well as a decrease in surface hydrophobicity and free SH content. Notably, the binding affinity between QPH and EGCG was observed to be higher at pH 7.0 compared to pH 3.0. Consequently, QPH-EGCG complexes exhibited more significant enhancement in antioxidant and emulsification properties at pH 7.0 than pH 3.0. The pH level also influenced the droplet size, ζ-potential, and interfacial composition of emulsions formed by QPH and QPH-EGCG complexes. Compared to QPH stabilized emulsions, QPH-EGCG stabilized emulsions were more capable of mitigating destabilization during storage and displayed fewer lipid oxidation products, carbonyl generation, and sulfhydryl groups and fluorescence loss, which implied better oxidative stability of the emulsions. Furthermore, the QPH-EGCG complexes formed at pH 7.0 exhibited better inhibition of protein hydrolysate-lipid co-oxidation. Overall, these findings provide valuable insights into the potential application of QPH and its complexes with EGCG in food processing systems.