Astaxanthin-loaded zein/calcium alginate composite microparticles: Characterization, molecular interaction and release kinetics in fatty food simulant system

Astaxanthin (Asta), extracted from shrimp (Litopenaeus vannamei) by-products, was used to fabricate Asta-loaded zein microparticles coated with resulting calcium alginate (CA) layer. The encapsulation efficiency of Asta to zein/CA (freeze dried, 40 degrees C or 50 degrees C oven dried) was across 80%. Some pits were distributed on CA coating layer under scanning electronic microscopy observation. Hydrogen bonding, hydrophobic effects and electrostatic attractions were involved in the interactions of Asta-loaded zein/CA microparticles fabrication by X-ray diffraction, Fourier-transform infrared spectroscopy, and differential scanning calorimetry assays. All of Astaloaded zein/CA microparticles displayed a two-step biphasic process, initial burst effect followed by subsequent attenuating release, in simulating fatty food system at 4 degrees C and 25 degrees C. The cumulative release of Asta from all of the experimental microparticles fit best with Higuchi model at 25 degrees C. Comparably, the release of Asta from oven dried groups fit best with First-order model (40 degrees C oven dried group), and Ritger-Peppas model (50 degrees C oven dried group) at 4 degrees C. The release kinetics suggested that the release of Asta from the skeleton of the microparticles had a good correlation with time, and could be explained by Fickian diffusion mechanism. Our research proposed a delicate and convenient approach for the controlled release of Asta in fatty food system.