Abstract: This study investigated the effects of different carriers on the digestion and absorption of astaxanthin from Pacific white shrimps aiming to provide a reference for the development and utilization of astaxanthin. Astaxanthin liposomes and astaxanthin microcapsules were successfully prepared by the thin-film ultrasonic method and the antisolvent precipitation method, respectively, and their physiological and biochemical properties were evaluated. Experimental results showed that excess amounts of wall material made the system unstable, thereby impacting the encapsulation efficiency. Additionally, a larger amount of the stabilizer cholesterol in liposomes did not necessarily lead to better results. Under optimized conditions, the encapsulation efficiencies of both astaxanthin liposomes and microcapsules were above 85%, the former being somewhat higher than the latter. The optimized preparation conditions for astaxanthin microcapsules were 2.5% zein concentration, 0.005% astaxanthin stock solution, and ultrapure water at pH 7, and those for astaxanthin were 4% soy lecithin concentration, 0.6% cholesterol concentration, and 0.004% astaxanthin stock solution concentration. Particle size analysis and transmission electron microscopy (TEM) showed that both samples were spherical particles of approximately 100 nm in diameter with smooth surfaces and fully encapsulated structures. In storage stability experiments, freeze-dried microcapsule powder exhibited the highest retention rate of astaxanthin (82.57%), but when preserved in liquid form, the retention rate of astaxanthin microcapsules was lower than that of astaxanthin liposomes. Encapsulated astaxanthin had higher antioxidant capacity than astaxanthin-containing oil at the same concentration. In in vitro simulated gastrointestinal digestion, the digestibilities of both astaxanthin liposomes and microcapsules were above 86%, the former being the latter. Both of them were immune to simulated gastric juice, and astaxanthin was slowly released from them in the simulated intestinal environment after gastric digestion, ensuring its absorption and utilization in the intestine tract. Astaxanthin-containing oil, astaxanthin liposomes and microcapsules diluted 5 and 10 folds were non-toxic to Caco-2 cells, and inhibited the production of reactive oxygen species (ROS) in oxidatively stressed cells. Among them, astaxanthin liposomes exhibited the highest absorption and transport efficiency and the strongest antioxidant activity. Astaxanthin, oil, lecithin, and zein could be absorbed by Caco-2 cells, but due to the limitations of conditions, Caco-2 cells absorbed more astaxanthin liposomes and astaxanthin-containing oil.

Key words: astaxanthin; deep eutectic solvent; microcapsule; liposome; Caco-2 cells