Abstract: Pigment composition and content of the diatom Odontella aurita were analyzed by reverse-phase HPLC, and a study of extraction of fucoxanthin from the freeze-dried powder of Odontella aurita was carried out using supercritical carbon dioxide. The results demonstrated that major pigments in the microalgae were fucoxanthin, diadinoxanthin, β-carotene, diatoxanthin, chlorophyll a and chlorophyll c1. Fucoxanthin was the most abundant carotenoid in the microalgae with a high content of 9.22 μg/mg dry weight. The yields of pigment extracted were positively related to temperature, pressure, addition amount of modifier and extraction time. Among the factors tested, the additional amount of modifier showed a greatest impact on pigment extraction yields, while the CO2 flow rate was the smallest factor. Although the fucoxanthin yield extracted by SFE-CO2 was lower, the SFE-CO2 was more conducive to fucoxanthin selectively extraction, separation and purification compared to organic solvent extraction. The suitable conditions for the SFE-CO2 of fucoxanthin were 400 bar, 50 ℃, CO2 flow rate 0.2 L/min, addition amount of modifier 10% and extraction time 2~3 h.

Key words: Odontella aurita, HPLC, supercritical carbon dioxide extraction, pigment