Solubilization of Hydrophobic Astaxanthin in Water by Physical Association with Phytoglycogen Nanoparticles

Astaxanthin (AXT) is a xanthophyll carotenoid with reported health benefits. Realizing its potential as a bioactive is challenging because of its extremely poor solubility in water. We describe a method to improve the effective solubility of AXT in water through its physical association with phytoglycogen (PG), which is produced in sweet corn as compact, highly branched nanoparticles. We combine PG in water with AXT in acetone, evaporate the acetone, and lyophilize. The result is an AXT-PG complex that can be readily redispersed in water, resulting in stable aqueous dispersions. By characterizing the UV-vis absorbance due to different aggregation states of AXT in the AXT-PG complex, we determined the maximum loading of AXT onto PG to be ∼10% by mass. Our results demonstrate the promise of using PG as a solubilizing agent for hydrophobic compounds in water.