Extraction of fucoxanthin, antioxidants and lipid from wet diatom Chaetoceros simplex var. calcitrans by liquefied dimethyl ether

Abstract

The co-production of lipids and high value-added products from microalgae is a key milestone for practical, microalgae-derived food and biofuel production. However, the use of ethanol as a solvent for lipid extraction requires a drying pretreatment to avoid wastewater contamination and large energy consumption during solvent recovery. Previous studies on lipid production have reported liquefied dimethyl ether (DME) as an alternative solvent that can extract lipids from high water content microalgae with low energy consumption by eliminating the traditional drying step. In this study, liquefied DME is used as a solvent to extract fucoxanthin, antioxidants, and lipids from wet diatom Chaetoceros simplex var. calcitrans. DME extracted 9.2 mg/g-dry microalgae of fucoxanthin from wet sample; this is slightly less than the 11.9 mg/g-dry microalgae extracted from dry sample by ethanol. The total phenolic content and antioxidant capacity of the liquefied DME extracts were only slightly lower than those of the ethanol extract. Using DME, all water and 22.7 wt% of lipid, and 5.6 wt% of atty acid were extracted. Lipids extracted with liquefied DME have a higher C/N, an indicator of suitability for conversion to biofuel, than lipids obtained by ethanol extraction. The microalga contains high levels of unsaturated fatty acids. Liquefied DME extraction is sustainable method because liquefied DME can extract most of the lipids and functional components without drying the diatom. DME avoids risks associated with ethanol.