Protection of astaxanthin from photodegradation by its inclusion in hierarchically assembled nano and microstructures with potential as food

Astaxanthin is a light sensitive molecule which is already approved as a dietary supplement, with a wide range of biological properties in humans and fishes. In this paper, we provide strategies to photostabilize the pigment through its inclusion in easy-to-prepare and scale up formulations, comprising non-toxic excipients. Astaxanthin has been formulated in biocompatible hierarchically assembled structures in order to produce model food to humans and fishes. The structures present increasing complexity in the following order: 1) oily nanodroplets stabilized by phospholipids; 2) chitosan-coated nanoemulsions produced after coating the nanodroplets with chitosan; 3) carrageenan-coated nanoemulsions produced after coating chitosan-coated nanoemulsions with carrageenan; 4) calcium alginate and chitosan tripolyphosphate beads including one of the nanosystems. The sensitivity to UV light of astaxanthin in both the nanosystems and the hydrogels has been evaluated. The nanoformulations produce protection of astaxanthin from photodegradation in the order nanoemulsions > carrageenan-coated nanoemulsions > chitosan-coated nanoemulsions. Chitosan beads furnish higher protection to astaxanthin than alginate beads. In a preliminary assay in fishes, alginate beads of 2–3 mm and 160 μm containing the nutrient were supplied to adult Danio rerio and juvenile Eleginops maclovinus, respectively. Both living species showed high rates of capturing the hydrogels in the water column, corroborating the attractiveness of the formulations as food for fishes. Due to the easy preparation of the formulations (that exclude thermal treatment or the use of toxic solvents), and the flexibility of these hierarchically assembled materials to incorporate other active molecules (proteins, polyunsaturated fatty acids, oligoelements, oral vaccines, antibiotics, antiparasitic, etc.), we postulate these formulations as ideal platforms to create foods for humans and animal species.