Pea protein isolate-gum Arabic Maillard conjugates improves physical and oxidative stability of oil-in-water emulsions

The Effect of (-)-Epigallocatechin-3-Gallate Non-Covalent Interaction with the Glycosylated Protein on the Emulsion Property

The effect of (−)-epigallocatechin-3-gallate (EGCG) on protein structure and emulsion properties of glycosylated black bean protein isolate (BBPI-G) were studied and compared to native black bean protein isolate (BBPI). The binding affinity of BBPI and BBPI-G with EGCG belonged to non-covalent interaction, which was determined by fluorescence quenching. EGCG attachment caused more disordered protein conformation, leading to a higher emulsification property. Among the different EGCG concentrations (0.10, 0.25, 0.50 mg/mL), the result revealed that the highest level of the emulsification property was obtained with 0.25 mg/mL EGCG. Therefore, the BBPI-EGCG and BBPI-G-EGCG prepared by 0.25 mg/mL EGCG were selected to fabricate oil-in-water (O/W) emulsions. After the addition of EGCG, the mean particle size of emulsions decreased with the increasing absolute value of zeta-potential, and more compact interfacial film was formed due to the higher percentage of interfacial protein adsorption (AP%). Meanwhile, EGCG also significantly reduced the lipid oxidation of emulsions.

Gum Arabic-Mediated Synthesis of Glyco-pea Protein Hydrolysate via Maillard Reaction Improves Solubility, Flavor Profile, and Functionality of Plant Protein

Pea protein hydrolysate (PPH) is successfully conjugated with gum arabic (GA) through Maillard-driven chemistry. The effect of cross-linking conjugation on the structure, solubility, volatile substances, emulsification, and antioxidative activity of glyco-PPH is investigated, and found to improve all properties. The formation of glyco-PPH is confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM). Size exclusion chromatography-multi angle light scattering (SEC-MALS) unveils that the maximum molecular mass of glyco-PPH occurs after 1 day of conjugation and approximately 1.2 mol of gum arabic conjugates on one mole of PPH. Headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) reveals the odor changes of glycoprotein before and after cross-linking. We have also prepared oil-in-water emulsions using glyco-PPH, which have enhanced physical stability against pH changes and chemical stability against lipid oxidation. The mechanism proposed involves Maillard-driven synthesis of the cross-linked PPH-GA conjugates, which increase the surface hydrophilicity and steric hindrance of glyco-PPH. These findings could provide a rational foundation for tailoring the physicochemical properties and functionalities of plant-based protein, which are attractive for food and functional materials applications.

Lipo-Dipeptide as an Emulsifier: Performance and Possible Mechanism

A lipo-dipeptide (C₁₃-lysine-arginine, C₁₃-KR) was designed as a potential emulsifier with good emulsifying properties under acidic condition. Compared with two traditional emulsifiers (whey protein isolate and Tween 80), C₁₃-KR emulsion had the minimum mean size but the highest zeta potential (around +100 mV). Moreover, C₁₃-KR emulsion showed better stability against environmental stresses, such as high salt concentrations and high temperature. The C₁₃-KR particles had the fastest move rate around 400 Hz when it attained an equilibrium state. Furthermore, C₁₃-KR emulsifier could sharply reduce the interfacial tension and had the lowest tension value at the oil/water interface. The interfacial tension of C₁₃-KR emulsifier was only 3.6 mN/m (0.5% w/v). In conclusion, the lipo-dipeptide C₁₃-KR could be considered as an emulsifier to produce emulsion under acidic condition.