Binding a chondroitin sulfate-based nanocomplex with kappa-carrageenan to enhance the stability of anthocyanins

We fabricated a novel nanocomplex-embedded hydrogel system to facilitate the stabilization of blueberry anthocyanins (ATCs). The strategy involved the copigmentation between ATCs and chondroitin sulfate (CS) and subsequent incorporation into kappa-carrageenan (KC) hydrogel. Results showed that the CS-ATCs nanocomplex displayed a smoother and more regular structure due to the high charge density of CS. Dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FT-IR), and Thermogravimetric analysis (TGA) demonstrated the nanosize and spherical morphology of the nanocomplex. The result of stability assays revealed that the stabilizing effect of ATCs on nanocomplex depended on different storage conditions such as temperature, pH, and metal ions. The nanocomplex showed effective protection of ATCs from degradation when exposed to relatively low pH. The retention rate (RR) at pH 6.0 of CS-ATCs-KC, and 25 °C, for 5 h was 94.40%. The RR of CS-ATCs-KC was significantly higher than that at pH 1.0 (RR = 52.02%). Moreover, the maximum RR of ATCs in CS-ATCs-KC at different metal ions (Na+, K+) was higher but not significant. The maximum RR of ATCs at 0.2 M Na+ and K+ were 91.11% and 90.69%, respectively, with a difference of only 0.42%. This study could provide support for deep processing in the blueberry beverage industry, and make a significant contribution to the utilization of blueberry ATCs as a viable resource.