Enzyme-assisted extraction of fucoxanthin and lipids containing polyunsaturated fatty acids from Undaria pinnatifida using dimethyl ether and ethanol

Abstract

A novel method for the efficient extraction of fucoxanthin and lipids containing polyunsaturated fatty acids (PUFAs) from the brown seaweed Undaria pinnatifida was developed and demonstrated at a laboratory scale. U. pinnatifida, also known as Wakame, contains a number of biologically active lipophilic compounds, particularly fucoxanthin, which has anti-oxidant, anti-cancer, anti-obesity and anti-inflammatory properties. The yield of fucoxanthin and lipids containing PUFAs was determined by extraction from wet and freeze-dried seaweed using dimethyl ether (DME) and ethanol and from enzyme-pretreated seaweed using the same solvents. The highest yields of fucoxanthin (94%) and lipids (94%) rich in PUFAs were obtained from fresh (wet) U. pinnatifida by enzyme pre-processing, followed by extraction using DME with ethanol as a co-solvent. In comparison, ethanol extraction resulted in lower extraction yields for both fucoxanthin (86%) and lipids (73%) under the conditions described. Enzyme pre-processing using alginate lyase resulted in the hydrolysis of cell wall polysaccharides, resulting in high extraction yields. The hydrolysis time, pH and temperature were found to be the most important parameters for the enzyme pre-processing step and for minimizing fucoxanthin losses due to oxidative degradation. The removal of water-soluble compounds (polysaccharides) following the enzyme pre-treatment prior to DME extractions doubled the throughput and maximized the yield. The residual biomass was colorless or a pale-brown color after the DME extraction, which indicated the highly effective extraction of fucoxanthin. The PUFA content and fucoxanthin levels were not affected by the enzyme or extraction using the described enzyme-assisted DME+ethanol co-solvent process.