Multistage aqueous and non-aqueous extraction of bio-molecules from microalga Phaeodactylum tricornutum

A multi-step aqueous and non-aqueous extraction procedure was applied to recovery bio-molecules from Phaeodactylum tricornutum. The process include that physical pre-treatments (high voltage electrical discharges (HVED, 40 kV/cm, 1-8 ms, HVED samples) or high pressure homogenization (HPH, 1200 bar, 10 passes, P samples)) (1st step); aqueous extraction (2nd step); pigments extraction in ethanol (3rd step); and lipids extraction in CHCl3/MeOH (4th step). The extractability of ionics, carbohydrates, proteins, pigments and lipids for untreated, HVED and P samples were evaluated. The results evidenced that HVED allowed selective extraction of water soluble ionic products at 1st and 2nd steps. The maximum ionic concentrations were found for HVED samples. However, P samples resulted in higher contents of extracted components as compared to HVED samples (approximate to 1.5-fold of carbohydrates, approximate to 2.5-fold of proteins, approximate to 5-fold of carotenoids, and approximate to 3-fold of chlorophylls). Moreover, the non-aqueous extraction (3rd and 4th steps) allowed supplementary extraction of pigments and lipids. Industrial relevance: Pre-treatments by high voltage electrical discharge (HVED) or high pressure homogenization (HPH) allowed effective extraction of different bio-molecules from microalga biomass. The combination of HVED/HPH, aqueous and non-aqueous extraction allowed selective recovery of target molecules. The paper also presents a multistage extraction procedure allowed reducing the amount of toxic solvents, increasing the extraction efficiency, and reducing the energy consumption. These approaches opened the doors to high-efficiency recovery of valuable compounds from microalgae relevant for industrial application.