Resveratrol inhibits lipid and protein co-oxidation in sodium caseinate-walnut oil emulsions by reinforcing oil-water interface

• Published in: Food research international 2022-08, Vol.158, p.111541-111541, Article 111541
• Main Authors: Gong, Tian, Chen, Bang, Hu, Ching Yuan, Guo, Yu Rong, Shen, Ye Hua, Meng, Yong Hong
• Format: Article
• Language: English
• Subjects: Emulsion; Lipid oxidation; Protein oxidation; Resveratrol; Sodium caseinate; Walnut oil
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2022.111541

[Display omitted] •Resveratrol significantly improved NaCas-walnut oil emulsions’ physical stability.•Resveratrol was mainly located at the interface by binding to NaCas.•Resveratrol enhanced NaCas’ emulsification capacity and antioxidant capacities.•Resveratrol slowed down lipid-protein co-oxidation in emulsions.•Resveratrol interfered reaction pathways between protein and lipid oxidation products. Lipid-protein co-oxidation often causes nutrition loss, texture changes, and shortened shelf-life of emulsions. In this study, resveratrol significantly prevented lipid-protein co-oxidation in sodium caseinate (NaCas)-walnut oil emulsions, and the underlying mechanisms were explored in physical and chemical aspects. NaCas-walnut oil emulsions stabilized by resveratrol exhibited excellent physical stability at 55 °C for 12 days or at room temperature for 10 months due to forming a stable interfacial layer composed of resveratrol-modified NaCas. Furthermore, resveratrol binding caused NaCas structure’s partial unfolding and a ∼ 8% increase in hydrophobicity, in turn enhancing NaCas’ emulsification properties and electrostatic repulsion. Besides, more than 90% of resveratrol was loaded at the interface and enhanced NaCas’ Fe2+ chelating, DPPH scavenging abilities, and O2 quenching by ∼ 22.6%, 5.26 times, and 31.84%, respectively. Simultaneously, resveratrol significantly improved NaCas’ oxidative stability, as reflected by the decrease in adsorbed NaCas’ intrinsic fluorescence loss and protein carbonyls gain by ∼ 30% and 37%, respectively. Simultaneously, lipid hydroperoxides and TBARS were reduced by ∼ 30% and 20% in the NaCas-walnut oil emulsions containing 6 mM resveratrol than the control. Our findings contribute to further understanding of the possible interaction among lipid, protein, polyphenols, and their oxidative products at the oil–water interface, minimizing lipid-protein co-oxidation and extending functional oils’ shelf life. Finally, walnut oil emulsions with high physical and oxidative stabilities using resveratrol were prepared, further broadening resveratrol’s application in the food industry.