Evaluation of the physicochemical stability and digestibility of microencapsulated esterified astaxanthins using in vitro and in vivo models

Esterified astaxanthins are used as functional nutraceuticals in many food products. Unfortunately, their utilization is currently limited owing to their poor water solubility, chemical instability, and low bioavailability. In this study, esterified astaxanthin microcapsules were fabricated through electrostatic complexation of whey protein and gum arabic by adjusting the pH to 4.0. After their encapsulation, the stability of the esterified astaxanthins was effectively better than that of the oleoresin. In vitro tests revealed a 26% rate of astaxanthin release from the microcapsules, which was significantly higher than the 14.6% rate from the oleoresin (P < 0.05). In vivo experiments showed that the AUC0-t value after oral gavage of the microcapsules (8.23 ± 1.33 h·μg·mL−1) was approximately 2-fold higher than that after gavage of the oleoresin (3.72 ± 0.98 h·μg·mL−1). In conclusion, the bioavailability of esterified astaxanthins can be significantly improved by microencapsulation.