Nanostructured Lipid Carriers in Alginate Microgels for the Delivery of Astaxanthin

This study aims to enhance the stability and bioavailability of astaxanthin by loading it into nanostructured lipid carriers (NLCs), then incorporating the NLCs into alginate microgels. The NLCs (about 200 nm particle size) and alginate microgels (about 1 mm particle size) are prepared using high-pressure homogenization and injection-gelation methods, respectively. Based on in vitro dissolution assessments, the astaxanthin in alginate microgels dissolves more slowly than that in NLCs. In simulated gastric digestive juice, minimal dissolution of microgel-embedded astaxanthin is detected; however, in simulated intestinal digestive juice, the dissolution is appreciably accelerated. Moreover, the 2 h bio-accessibility of astaxanthin in microgels is less than that in NLCs. At higher concentrations of sodium alginate and calcium ions, the internal pores of the microgels become smaller, resulting in slower dissolution and lower bio-accessibility of astaxanthin. As for the chemical stability of the pigment, it is improved by the secondary coating effect of hydrogelation. Hence, NLC incorporation into alginate microgels constitutes a promising strategy for the encapsulation of astaxanthin in the food industry. Practical applications : Nanostructured lipid carriers (NLCs) incorporated in alginate microgels can increase the water solubility of astaxanthin, improve its chemical stability, increase its bioavailability, and allow for its controlled release. The high-pressure homogenization method used to prepare NLCs can be easily applied on an industrial level. Moreover, the operation conditions of the injection-gelation process needed to synthesize the alginate microgels are mild, nontoxic, and nonpolluting. The NLC-alginate microgels can be used in yogurt, ice cream, and other foods.

Automated summary

This study aimed to enhance the stability and bioavailability of astaxanthin by incorporating it into nanostructured lipid carriers (NLCs) and then into alginate microgels. The slow dissolution of astaxanthin in alginate microgels compared to NLCs was observed in vitro. The NLC-alginate microgels offer potential for encapsulating astaxanthin in the food industry for improved chemical stability and controlled release.