Supercritical CO2 extraction of Aurantiochytrium sp. biomass for the enhanced recovery of omega-3 fatty acids and phenolic compounds.

• SFE of microalgae Aurantiochytrium sp. and Soxhlet extraction (n-hexane & dichloromethane). • Maximization of total extraction yield, DHA & total phenolics content, & antioxidant capacity. • Design of experiments with 3 factors and 2 levels (200−300 bar, 40−80 °C, 6–12 g C O 2 m i n - 1). • Obtained DHA content 3.5-fold richer than fish oil, and 7.9-fold richer than other microalgaes. The microalgae Aurantiochytrium sp. is a strong alternative source of ω-3 fatty acids, including docosahexaenoic acid (DHA). This work encompasses the optimization of SFE conditions to maximize the total extraction yield η T o t a l , DHA content (C D H A), total phenolics content (T P C), and antioxidant capacity (A O C) of the extracts produced from Aurantiochytrium sp. biomass. A full factorial experimental plan was performed, comprising three factors (pressure, temperature, and flow rate) and two levels (200−300 bar, 40−80 °C, and 6–12 g m i n - 1 , respectively). The maximum and minimum experimental results were η T o t a l = 2.1 and 13.4 wt.%, C D H A = 27.3 and 39.3 wt.%, T P C = 1.19 and 2.24 m g G A E g e x t r a c t - 1 , and A O C = 0.3 and 1.4 m g T E A C g e x t r a c t - 1. Under the studied experimental conditions, increasing pressure up to 300 bar is the optimum to rise both η T o t a l and C D H A. Temperature increase from 40 to 80 °C leads to opposing effects: it favors the concentration of phenolics in the supercritical extracts at the expenses of decreasing DHA content and total yield. Surface models were adjusted to η T o t a l , C D H A and T P C data, and the goodness of the fits ranged from coefficients of determination of 0.752-0.711 (T P C) to 0.997-0.994 (C D H A). Under optimized conditions, supercritical extracts exhibited a DHA content more than 3.5-fold richer than fish oil, and 7.9-fold richer than the best alternative microalgae species (Pavlova lutheri) found in the literature. [ABSTRACT FROM AUTHOR]