Preparation, characterization, stability, and application in curcumin of the emulsion gels stabilized with coconut cake albumin modified by ultrasonication and carboxymethylation

Abstract

Background Curcumin has applications in food and medical industries, but its stability and bioaccessibility are poor. Coconut cake albumin (CCA) has potential as a component of the curcumin-loading system; however, relative data are scare. Methods Herein, emulsion gels were formed using coconut cake albumin modified by ultrasonication and carboxymethylation (CCA-UC) in this study. Results The results evidenced that ultrasonication and carboxymethylation increased the emulsifying capacity (from 67.51 to 143.65 m2/g) and emulsion stability (from 70.37 to 87.18%) of CCA by improving its solubility and interface sorption capacity, enhancing the zeta potential, and reducing droplets’ size (p < 0.05). CCA and CCA-UC formed compact emulsion gel when concentration was more than 10 g/100 g. Compared with the CCA-emulsion gel, CCA-UC-emulsion gel had more compact and denser gel structure, higher crystallinity (38.65%), bound water content and viscosity, and lower energy storage (G’), loss modulus (G”), and loss factor. Furthermore, CCA-UC-emulsion gel showed superior thermal and oxidative stability, and higher chewiness (35.83 g), springiness (0.90), hardness (67.44 g), and cohesiveness (0.85) than CCA-emulsion gel. Additionally, CCA-UC-emulsion gel exhibited superior intestinal digestion rate, higher curcumin encapsulation (89.64%) and loading efficiency (204.01 μg/g), better photostability, and superior bioaccessibility (49.08%). However, more specific mechanisms should be investigated in the further work. Conclusion These findings revealed that ultrasonication assisted with carboxymethylation was an effective way to improve the emulsion gel properties of CCA and increase the bioaccessibility of curcumin. However, more specific mechanisms should be investigated in the further work.