Evaluation and improvement of storage stability of astaxanthin isomers in oils and fats

Astaxanthin Z-isomers potentially have greater bioavailability and biological activity than (all-E)-astaxanthin. However, the stability of is lower all-E-isomer, which a serious problem affecting its practical use. In this study, we investigated impacts different suspension media (oils fats) additives on astaxanthin isomer identified suitable ones for stabilization. The evaluations showed that several vegetable oils antioxidants significantly improved stability, e.g., when soybean sunflower were used as medium, isomers hardly degraded; however total Z-isomer ratio decreased from ~80% to ~50% during 6-week storage at 30 °C. Moreover, it was revealed (9Z)-astaxanthin higher 13Z- 15Z-isomers. Hence, maintain concentration over long periods, important use mediums antioxidants, select Z-isomerization method increases ratio.