Complex formation and stabilization of Z-isomer-enriched astaxanthin esters derived from Haematococcus lacustris with water-soluble carriers via spray drying

To enhance the water solubility and bioavailability of astaxanthin esters, inclusion complexes of Z-isomer-enriched astaxanthin esters with water-soluble carriers were prepared using a spray drying technique. A food-grade Haematococcus alga extract was used as the source of astaxanthin esters, and the Z-isomerization was performed via direct heating of the extract. Polyvinylpyrrolidone (PVP) and hydroxypropyl-β-cyclodextrin (HP-β-CD) were used as water-soluble carriers. The effects of spray drying conditions on the encapsulation efficiency of astaxanthin esters in the carriers and the total Z-isomer ratio of encapsulated astaxanthin esters were investigated, and the physical properties and storage stability of the resulting composites were evaluated. Under optimum spray drying conditions, efficient production of highly water-soluble Z-isomer-rich astaxanthin esters was achieved in both carriers: >95% encapsulation efficiency and >55% total Z-isomer ratio. The physical properties, such as surface morphology and particle size distributions, of the resulting particles differed significantly between PVP and HP-β-CD. Storage tests demonstrated that the formulated Z-isomer-rich astaxanthin esters were highly stable. Our findings will contribute to the practical applications of Z-isomer-rich astaxanthin materials.

Practical Applications: The formulation technology developed in this study has the potential to address the industrial challenges of using astaxanthin, that is, low water solubility and low bioavailability. Furthermore, the low storage stability of astaxanthin Z-isomers, which hinders their industrial use, can be solved simultaneously. The resulting Z-isomer-rich astaxanthin powders are expected to be used in a wide range of applications, including nutraceuticals, cosmetics, and animal feeds.