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There is broad scientific evidence on the health benefits of omega-3 polyunsaturated fatty acids (n-3 PUFAs), especially docosahexaenoic acid (DHA, 22:6n3) and eicosapentaenoic acid (EPA, 20:5n3). On the other hand, polar lipids (phospholipids, PLs, and glycolipids, GLs) are excellent emulsifying agents, making them useful both as food products and as excipients for drugs and cosmetics. The bioavailability of n-3 PUFAs in the form of PLs is greater than that of ethyl esters and triacylglycerols. This work has developed an easy method for the simultaneous extraction and fractionation of saponifiable lipids (SLs) from the microalga Nannochloropsis sp., using low-toxicity solvents. Firstly, a lipidic fraction very rich in neutral saponifiable lipids (NSLs) was obtained using hexane. Next, an EPA and polar lipids (PLs and GLs)-enriched fraction was obtained using ethanol (96%). Under optimal conditions, in the first extraction with hexane, an SL extract with 86.3% NSLs was obtained; this extract contained 88.9% of the biomass NSLs. Subsequently, in the second extraction step with ethanol (96%), an SL extract with 87.1% polar lipids and up to 35.2% EPA was obtained. This SL extract contained 87.1% of the polar lipids and 74.7% of the EPA from the Nannochloropsis sp. biomass. [ABSTRACT FROM AUTHOR]

The aim of this work was to optimize the production of fatty acid methyl ester (FAME, biodiesel) from wet Nannchloropsis gaditana microalgal biomass by direct enzymatic transesterification. This was done in order to avoid the high cost associated with the prior steps of drying and oil extraction. Saponifiable lipids (SLs) from microalgal biomass were transformed to FAME using the lipase Novozyme 435 (N435) from Candida antarctica as the catalyst, and finally the FAME were extracted with hexane. t-Butanol was used as the reaction medium so as to decrease lipase deactivation and increase mass transfer velocity. A FAME conversion of 99.5% was achieved using wet microalgal biomass homogenized at 140 MPa to enhance cell disruption, a N435:oil mass ratio of 0.32, methanol added in 3 stages to achieve a total of 4.6 cm 3 g −1 of oil and 7.1 cm 3 g −1 oil of added t-butanol, with a reaction time of 56 h. The FAME conversion decreased to 57% after catalyzing three reactions with the same lipase batch. This work shows the influence of the polar lipids contained in the microalgal biomass both on the reaction velocity and on lipase activity. [ABSTRACT FROM AUTHOR]

In order to obtain microalgal saponifiable lipids (SLs) fractions containing different polar lipid (glycolipids and phospholipids) contents, SLs were extracted from wet Nannochloropsis gaditana microalgal biomass using seven extraction systems, and the polar lipid contents of some fractions were reduced by low temperature acetone crystallization. We observed that the polar lipid content in the extracted lipids depended on the polarity of the first solvent used in the extraction system. Lipid fractions with polar lipid contents between 75.1% and 15.3% were obtained. Some of these fractions were transformed into fatty acid methyl esters (FAMEs, biodiesel) by methanolysis, catalyzed by the lipases Novozym 435 and Rhizopus oryzae in tert-butanol medium. We observed that the reaction velocity was higher the lower the polar lipid content, and that the final FAME conversions achieved after using the same lipase batch to catalyze consecutive reactions decreased in relation to an increase in the polar lipid content. [ABSTRACT FROM AUTHOR]

Biodiesel (fatty acid methyl esters, FAMEs) was produced from saponifiable lipids (SLs) extracted from wet Nannochloropsis gaditana biomass using methanolysis catalyzed by Rhizopus oryzae intracellular lipase. SLs were firstly extracted with ethanol to obtain 31 wt% pure SLs. But this low SL purity also gave a low biodiesel conversion (58%). This conversion increased up to 80% using SLs purified by crystallization in acetone (95 wt% purity). Polar lipids play an important role in decreasing the reaction velocity – using SLs extracted with hexane, which have lower polar lipid content (37.4% versus 49.0% using ethanol), we obtained higher reaction velocities and less FAME conversion decrease when the same lipase batch was reused. 83% of SLs were transformed to biodiesel using a 70 wt% lipase/SL ratio, 11:1 methanol/SL molar ratio, 10 mL t-butanol/g SLs after 72 h. The FAME conversion decreased to 71% after catalyzing three reactions with the same lipase batch. [ABSTRACT FROM AUTHOR]

Fatty acid methyl esters (FAMEs, biodiesel) were produced from Nannochloropsis gaditana wet biomass (12% saponifiable lipids, SLs) by extraction of SLs and lipase catalyzed transesterification. Lipids were extracted by ethanol (96%)–hexane, and 31% pure SLs were obtained with 85% yield. When the lipids were degummed, SL purity increased to 95%. Novozym 435 was selected from four lipases tested. Both the lipidic composition and the use of t-butanol instead of hexane increased the reaction velocity and the conversion, since both decreased due to the adsorption of polar lipids on the lipase immobilization support. The best FAME yield (94.7%) was attained at a reaction time of 48 h and using 10 mL of t-butanol/g SL, 0.225 g N435/g SL, 11:1 methanol/SL molar ratio and adding the methanol in three steps. In these conditions the FAME conversion decreased by 9.8% after three reaction cycles catalyzed by the same lipase batch. [ABSTRACT FROM AUTHOR]

The objective of this work is to develop a process for producing biodiesel from the saponifiable lipid (SL) fraction of the wet microalgal biomass Nannochloropsis gaditana . The method consists of five steps. Firstly, crude fatty acid salt extraction was carried out using a KOH-ethanol (96%) solution, which allows one to extract the SLs as potassium salts. This transformation permits better separation of the unsaponifiable lipids (the second step) and finally produces purer biodiesel. The unsaponifiable lipids were then separated with hexane, after establishing the ethanol-water solution water content at 30% w/w. Some unsaponifiable lipids (carotenoids and phytosterols) are products of interest that might be purified from this fraction thus helping to improve the process's profitability. Thirdly, free fatty acids (FFAs) were purified by acidification of the ethanol-water solution to pH 5 and were then extracted with hexane. Fourthly, the FFAs were transformed to biodiesel by esterification with excess of methanol catalyzed using sulphuric acid, removing the excess by washing with hot water. Under these conditions the biodiesel purity and yield were 74.8% and 82% w/w, respectively. Finally, the biodiesel was clarified/purified up to 96.5% purity by adsorption with bentonite. The final biodiesel yield was 80.9%. [ABSTRACT FROM AUTHOR]

Saponifiable lipids (SLs) were extracted with hexane from wet biomass (86 wt% water) of the microalga Nannochloropsis gaditana in order to transform them into fatty acid methyl esters (FAMEs, biodiesel). The influence of homogenization pressure on SL extraction yield at low temperature (20–22 °C) was studied. Homogenization at 1700 bar tripled the SL extraction yield. Two biomass batches with similar total lipid content but different lipidic compositions were used. Batch 1 contained fewer SLs (12.0 wt%) and neutral saponifiable lipids (NSLs, 7.9 wt%) than batch 2 (21.6 and 17.2 wt%, respectively). For this reason, and due to the selectivity of hexane toward NSLs, high SL yield (69.1 wt%) and purity (71.0 wt%) were obtained from batch 2. Moreover, this extract contains a small percentage of polyunsaturated fatty acids (16.9 wt%), thereby improving the biodiesel quality. Finally, up to 97.0% of extracted SLs were transformed to FAMEs by acid catalyzed transesterification. [ABSTRACT FROM AUTHOR]

The aim of this work was to obtain biodiesel (methyl esters) from the saponifiable lipids (SLs) fraction of the microalga Nannochloropsis gaditana , whose biomass dry weight contains 12.1 wt% of these lipids. SLs were extracted from the microalga as free fatty acids (FFAs) for subsequent transformation to methyl esters (biodiesel) by enzymatic esterification. Extraction as FFAs rather than as SLs allows them to be obtained with higher purity. Microalgal FFAs were obtained by direct saponification of lipids in the biomass and subsequent extraction-purification with hexane. Esterification of FFAs with methanol was catalysed by lipase Novozym 435 from Candida antarctica . Stability studies of this lipase in the operational conditions showed that the esterification degree (ED) attained with the same batch of lipase remained constant over six reaction cycles (36 h total reaction time). The optimal conditions attained for 4 g of FFAs were 25°C, 200 rpm, methanol/FFA molar ratio of 1.5:1, Novozym 435/FFA ratio of 0.025:1 w/w and 4 h reaction time. In these conditions the ED attained was 92.6%, producing a biodiesel with 83 wt% purity from microalgal FFAs. Several experimental scales were tested (from 4 to 40 g FFAs), and in all cases similar EDs were obtained. [ABSTRACT FROM AUTHOR]

The thraustochytrid Aurantiochytrium limacinum SR21 is a promising source of docosahexaenoic acid (DHA) for human consumption as dietary supplement, replacing traditional fish oil. This work deals with the production of structured triacylglycerols (STAGs) with caprylic acid (CA) located at sn-1,3 positions and DHA at sn-2 position of the glycerol molecule. This process is conducted by acidolysis of CA and A. limacinum SR21 oil catalyzed by Lipozyme TL-IM and Lipozyme RM-IM. A central composite design with response surface was used to optimize the reaction temperature and the intensity of treatment (IOT). Statistical models adequately describe the reaction behavior (R2 > 0.91). The optimal temperature values were 37 °C for both lipases. Additionally, IOTs of 9.02 and 7.87 g lipase h g−1 TAG were stablished for TL-IM and RM-IM, respectively. The reaction was scaled up by multiplying the amounts of A. limacinum oil, CA, lipase, and hexane (used as reaction medium) by a factor of 20 while maintaining the IOTs constant. TL-IM showed a better performance to catalyze the acidolysis reaction than RM-IM, achieving 40.8 mol% of total CA incorporated (91.2% of total incorporated at sn-1,3 positions), while the palmitic acid (PA) content at sn-1,3 positions decreased from 77.3 to 20.4 mol%. DHA represented 45.5 mol% of fatty acids at sn-2 position and 15.7 mol% of fatty acids at sn-1,3 positions. Using RM-IM, STAGs of similar composition were obtained. [ABSTRACT FROM AUTHOR]

The aim of this work was to produce docosahexaenoic acid (DHA)-enriched acylglycerols through the alcoholysis of tuna oil (24–26% DHA) using ethanol, dodecanol and isobutanol as the acyl-acceptors. The alcoholysis reaction was catalyzed using Thermomyces lanuginosus lipase (Lipozyme TL IM) and was carried out both in solvent-free medium and using tert -butanol to increase lipase stability. Studies were carried out to determine the influence of the reaction time and the lipase/oil ratio. The tuna oil’s DHA content was trebled (from 26 to 78 wt%) using isobutanol as the acyl acceptor while carrying out the alcoholysis reactions in solvent-free medium. However, under these conditions, the lipase was partially deactivated given that the conversion rate decreased by around 80% after catalyzing six successive reactions using the same lipase batch. With tert -butanol as the reaction medium, the lipase was more stable but the resulting DHA concentrations were lower: 56% with isobutanol and dodecanol (59% with dodecanol in solvent-free medium) and 42.5% with ethanol (47.5 % without solvent). [ABSTRACT FROM AUTHOR]