Enhanced triacylglyceride extraction from microalgae using free nitrous acid pre-treatment

Triacylglyceride (TAG) recovery from algal biomass is primarily limited by the rigid algal cell envelope (cell wall and cell membrane). In this work, the effect of free nitrous acid (FNA) pre-treatment on TAG recovery from algal biomass with six different FNA concentrations is reported. Results show that at a range of low FNA concentrations (0.24-2.25 mg HNO2-N L-1) TAG recovery was strongly enhanced with increasing FNA concentration. An FNA concentration of around 2 mg HNO2-N L-1 resulted in a 3.3-fold increase in fatty acid recovery over untreated algae, but higher FNA concentrations (13.49 and 26.98 mg HNO2-N L-1) were detrimental to TAG recovery. Analysis of the fatty acid profile revealed that the higher FNA concentrations caused a reduction in polyunsaturated fatty acids. Also, the ratio of extracted fatty acids to total lipids was significantly reduced when high FNA concentration were applied, and only non-fatty acid lipids potentially benefited from more intense FNA pre-treatments. (C) 2015 Elsevier Ltd. All rights reserved.