The effects of particle size on the physicochemical properties of optimized astaxanthin-rich Xanthophyllomyces dendrorhous-loaded microparticles

- ASX was successfully incorporated into calcium alginate microparticles.
- The optimized microparticles were prepared to improve entrapment efficiency (EE).
- Increasing microparticle size increased EE and antioxidant activity of ASX.
- The released contents of entrapped ASX decreased with an increase in particle size.
- Antioxidant activity of entrapped ASX was higher than that of non-encapsulated ASX.

To improve the entrapment efficiency (EE) of astaxanthin-rich Xanthophyllomyces dendrorhous (ASX)-loaded calcium alginate gel (ASX-CAG) microparticles, we used a response surface methodology to optimize preparation conditions including the ratio of ASX to total material (X1), alginate concentration (X2), and CaCl2 concentration (X3). The EE and the mean size of the ASX-CAG microparticles were 76.7 g/100 g and 210.26 μm, respectively, after preparation under optimal conditions: 24 g ASX/100 g total material, 1.0 g/100 g alginate, and 200 mmol/L CaCl2. The effects of particle size on different characteristics were evaluated with increasing microparticle size; an increase in microparticle size significantly increased EE and the antioxidant activity of ASX, but resulted in a decrease in the release of entrapped ASX. Most importantly, the lipid peroxidation inhibitory activity of encapsulated ASX (55.1%) was significantly higher and longer-lasting than that of non-encapsulated ASX (40.5%) after 36 h of storage as determined using the thiobarbituric acid method.