Astaxanthin (3,30-dihydroxy-β-carotene-4,40-dione) is a carotenoid pigment. Due to its highly unsaturated structure, astaxanthin is easily damaged under unfavorable process conditions such as acidic environments, heat, light, transition metal ions, singlet oxygen, free radicals, etc., especially after removal from its biological matrix. This may result in the loss of their desirable nutritional and biological properties, as well as the production of undesirable flavor and aroma compounds. In addition, astaxanthin has poor solubility in water (83 mg/L) as well as its limited solubility in lipid blood components. Thus, astaxanthin is characterized by very low bioavailability. Therefore, there have been various researches on the methods of astaxanthin stabilization and improvement of its bioavailability [1].

• Production of hydrophilic stable and bioactive derivatives

A great number of researches have been done, In order to improve the stabilization of astaxanthin and enhance its bioavailability. For example, the production of hydrophilic stable and biologically active pigment derivatives, e.g., various esters of astaxanthin, such as disodium disuccinate astaxanthin, tetrasodium diphosphate astaxanthin and various fatty acid esters of astaxanthin.

• Microencapsulation and nano-encapsulation techniques

The introduction of astaxanthin into aqueous food systems and other complex environments typically results in the formation of oil-in-water (O/W) emulsions. And many studies have shown that high stability, water solubility and high bioavailability of astaxanthin dispersions can be easily achieved by microencapsulation and nano-encapsulation techniques. To achieve encapsulation of bioactive food compounds, polymeric carriers are usually used. They should be compatible with the product properties (flavor, texture, shelf life), biodegradable and easy to use.