Supercritical carbon dioxide extraction of antioxidant rich fraction from Phormidium valderianum: Optimization of experimental process parameters

•Supercritical carbon dioxide extraction of Phormidium valderianum•Optimization of extraction parameters•Characterization of the algal extracts•Antioxidant-rich algal extracts with minimum toxicity

Extraction of antioxidant-rich fractions from lyophilized algal biomass of Phormidium valderianum was carried out by green technology of supercritical carbon dioxide (SC-CO2) extraction. Optimization of extraction parameters (temperature and pressure) was carried out to obtain an extract that has the best combination of phytochemical properties (phenolic content, carotenoid content, reducing power and antioxidant activity) with minimum toxin content (Anatoxin-a). The algal extract obtained by SC-CO2 from 10 g biomass at 50 °C, 500 bar after 1.5 h extracting time at a flow rate of 2 l min− 1 of gaseous CO2 had maximum phytochemical properties with ~ 93% reduction of Anatoxin-a content. This investigation provides an alternative method for obtaining natural antioxidants from algae for food and pharmaceutical applications.