Sonication and sodium alginate synergistically modify whey protein emulsion gels for enhanced delivery of astaxanthin bioaccessibility

Astaxanthin's immense health benefits are hampered by its chemical instability and poor bioaccessibility. Conventional whey protein concentrate (WPC) carriers offer limited protection. The study aimed to develop a superior delivery system by constructing a WPC-based emulsion gel synergistically modified with sodium alginate (SA) and ultrasound. The combined treatment (0.75 % for SA, 200 W for ultrasonic power, 40 °C for ultrasonic temperature and 20 min for ultrasonic time) yielded a robust carrier with high encapsulation efficiency (over 90 %) and water-holding capacity (96.5 ± 1.02 %), achieving an astaxanthin retention of 80.96 ± 0.24 % and a bioaccessibility of 60.15 ± 0.96 %, which significantly surpasses that of conventional WPC systems. The primary advantage of this strategy lies in the synergistic creation of a denser gel network, which enhances physical stability and provides superior protection during digestion. These findings demonstrate the high potential of this SA-sonication strategy for developing high-performance bioactive delivery systems in functional foods and nutraceuticals.