Construction and Evaluation of Steady-State System of Anthocyanin-Chondroitin Sulfate Co-pigmentation Complex Binding to Pullulan

In this study, a co-pigmentation complex formed by ionic complexation of blueberry anthocyanins (BA) with chondroitin sulfate (CS) was bound to pullulan (PU) to prepare a steady-state BA-CS-PU system by a combination of co-pigmentation and encapsulation technology. The co-pigmentation and stabilizing effects of CS on BA were evaluated by ultraviolet-visible (UV-visible) spectroscopy and color parameters. The structure of BA-CS-PU was characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA), and the mechanism of co-pigmentation and encapsulation was explained. The processing and digestive stability of the steady-state system were evaluated under simulated heat, acid-base strength, co-existence with vitamin C (VC) and in vitro digestion conditions. The results showed that the addition of CS caused a red shift in the UV spectrum and an increase in absorbance, and enhanced the redness, thereby resulting in co-pigmentation effect, which was related to the ionic complexation between the sulfate group of CS and the flavylium ion of BA. The encapsulation effect of PU could be achieved through hydrogen bonding. In addition, co-pigmentation with CS and encapsulation with PU significantly improved the retention rate and a value of BA under heat, acid-base strength and VC co-existence conditions, and also enhanced the gastrointestinal digestive stability, with an 8.63% increase in retention rate. The results of this study provide a basis for in-depth processing of anthocyanin-rich berries.