Polyethyleneimine as a tool for compounds fractionation by flocculation in a microalgae biorefinery context

In the context of emerging biorefinery for microalgae, polyethyleneimine (PEI), has been tested in order to achieve separation of fat-soluble and water-soluble compounds from Haematococcus pluvialis. Several parameters were taken into account (ratio between sample and PEI, pH, and ionic strength) and 2 conditions (0.075% PEI pH 7.4, and 0.100% PEI pH8.5) were studied for up-scalability, with a recovery of flocculated compounds (lipids and pigments), and a complete characterization of both phases. Using 0.075% PEI, pH7.4, 100% sugars and 89.8% proteins were retained in the supernatant, but some trace of beta-carotene were also detected. For 0.100% PEI, pH 8.5, a loss in proteins content was highlighted (61.2% proteins retained), but no residual lipids or pigments were detected. PEI could therefore be considered as an efficient method to fractionate fat-soluble and water-soluble compounds from microalgae.