Biobased Solvents for Pressurized Liquid Extraction of Nannochloropsis gaditana Omega-3 Lipids

Abstract

To develop greener extraction alternatives for microalgae biomass, ultrasound assisted extraction (UAE) and pressurized liquid extraction (PLE) with different biobased solvents were investigated, demonstrating that both techniques are useful alternatives for algal lipid extraction. Specifically, Nannochloropsis gaditana lipids were extracted by UAE and PLE at different temperatures and extraction times with sustainable solvents like 2-Methyltetrahydrofuran (2-MeTHF) and its mixtures with ethanol and other alcohols. The best oil yields for both PLE and UAE of N. gaditana were achieved with the mixture of 2-MeTHF:ethanol (1:3), reaching yields of up to 16.3%, for UAE at 50 °C and up to 46.1% for PLE at 120 °C. Lipid composition of the extracts was analyzed by HPLC-ELSD and by GC-MS to determine lipid species and fatty acid profile, respectively. Different fractionation of lipid species was achieved with PLE and solvent mixtures of different polarity. Thus, for the extraction of glycolipids, ethanolic extracts contained higher amounts of glycolipids and EPA, probably due to the higher polarity of the solvent. The optimized method was applied to microalgae Isochrysis galbana and Tetraselmis chuii showing the potential of mixtures of biobased solvents like 2-methyl-THF and ethanol in different proportions to efficiently extract and fractionate lipids from microalgal biomass.

Combination of Synergic Enzymes and Ultrasounds as an Effective Pretreatment Process to Break Microalgal Cell Wall and Enhance Algal Oil Extraction

“…Previous studies of the research group demonstrated that it was possible to enrich and fractionate neutral and polar lipids using enzymatic pretreatment and pressurized liquid extraction (PLE) from microalgae [1,3,12]. In the present work, the combination of different commercial enzymes, including a wide range of carbohydrases (Viscozyme ® and Celluclast ® ) and protease (Alcalase ® ), were tested in combination with other methods to enhance and optimize polar lipid recovery of N. gaditana dry biomass.…”

“…Among different microalgae that are harvested worldwide, Nannochloropsis gaditana is described to produce a wide range of polar lipids, including omega-3 polyunsaturated fatty acids (PUFAs) and carotenoids such as lutein, which have widely recognized benefits related to human health. Indeed, PUFA produced by microalgae exhibit antioxidant, antibacterial, antiviral, and detoxifying capacities; prevents hypercholesterolemia; improves Foods 2021, 10, 1928 2 of 14 brain function; and is proved to have good immune-stimulatory effects [1,2]. Nannochloropsis gaditana has been described to produce high amounts of lipids.…”

“…Nowadays, the vegetable oil extraction industry uses large volumes of hexane and long extraction times that cause environmental problems due to direct losses of organic solvents into the atmosphere; hence, greener alternatives are needed. In recent years, there have been important advances in the development, optimization, and applications of green extraction techniques in the food industry to reduce the environmental impact by waste minimization, decrease energy consumption and processing time, and avoid health hazards by substituting toxic and unsafe solvents and developing green pretreatment methods that facilitate posterior oil extraction [1,3,11].…”

Fatty Acid Composition and Cytotoxic Activity of Lipid Extracts from Nannochloropsis gaditana Produced by Green Technologies

“…Ho et al [31] used a similar strategy to extract the omega-3 EPA but using subcritical water. The use of pressurized liquids has also been reported by several authors [10,32,33]. Moreover, in a recent study, Jiménez Callejón et al, [34] investigated the simultaneous extraction and fractionation of polar lipids by using supercritical and pressurized liquids.…”

Cross-Linked Enzyme Aggregates and Their Application in Enzymatic Pretreatment of Microalgae: Comparison Between CLEAs and Combi-CLEAs

“…Moreover, the composition of microalgae highly varies among the different species, which make them more versatile. On its own, Nannochloropsis gaditana is described as a microalga able to produce important amounts of lipids, including polar lipids, omega-3 polyunsaturated fatty acids, and carotenoids such as carotenes and xanthophylls, which have benefits for human health widely recognized ( Yen et al, 2013 ; Gong and Bassi, 2016 ; Castejón et al, 2018 ; Castejón and Señoráns, 2019 ; Punia et al, 2019 ; Zhang et al, 2019 ; Castejón and Señoráns, 2020 ; Katiyar and Arora, 2020 ; Señoráns et al, 2020 ; Blanco-Llamero and Señoráns, 2021 ).…”