Utilization of layer-by-layer deposition to improve the stability of astaxanthin emulsions: Triple-layer coatings formed using sodium caseinate-pectin-chitosan

This study aimed to develop a good multilayered emulsion delivery system to improve the stability of astaxanthin. The layer-by-layer (LBL) electrostatic deposition technique was utilized to prepare sodium caseinatepectin-chitosan astaxanthin multilayered emulsions. The stabilities of the emulsions and astaxanthin under different environmental stresses were investigated. Results showed that the droplet size of sodium caseinatepectin double-layer emulsion (CS/P-e), sodium caseinate-chitosan double-layer emulsion (CS/CTS-e) and sodium caseinate-pectin-chitosan triple-layer emulsion (CS/P/CTS-e) varied less with pH and salt ions than that of sodium caseinate single-layer emulsion (CS-e). The droplet size of triple-layer emulsion changed the least after storage and freeze-thaw cycles compared with that of single- and double-layer emulsions. After thermal, freeze-thaw cycle, storage, and ultraviolet irradiation treatments, the stability of astaxanthin in multilayered emulsions was higher than that in single-layer emulsion, and the retention rate of astaxanthin increased as the number of interfacial layers increased. Furthermore, the free fatty acid (FFA) release of CS/P-e and CS-e was higher than that of CS/CTS-e and CS/P/CTS-e, and multilayered emulsions improved the bioaccessibility of astaxanthin. These findings provided a theoretical basis for triple-layer emulsions to deliver bioactive substances.