Lipid Extraction Yield Research Articles

Evaluation of methods to extract and quantify lipids from Synechocystis PCC 6803

In order to use the photosynthetic cyanobacterium Synechocystis as a source of feedstock for carbon-neutral, nonpetroleum-based diesel fuel, we evaluated several solvents and solvent systems for their ability to extract lipid from wild-type Synechocystis PCC 6803. Chloroform+methanol-based Folch and Bligh & Dyer methods had the highest lipid recoveries. Less toxic solvents, such as methanol and MTBE, or direct trans-esterification of biomass (without pre-extraction step) gave only slightly lower lipid-extraction yields. Ethanol, isopropanol, butanol, hexane, acetic ester, and their combinations were not effective for lipid extraction from Synechocystis (>20% loss), even though they are widely used for non-polar lipid extraction from other feedstock, including algae. We confirmed the success of chloroform+methanol-based extraction by their penetration of the cell membrane system, higher polarity, and stronger interaction with hydrogen bonds. The less-polar solvents not only had lower lipid yield, but also extracted more non-lipid compounds that require extra purification to remove. We also characterized the fatty-acid profile of Synechocystis PCC 6803: C16:0 (∼60%), C16:1 (∼9.5%), C18:0 (∼1.2%), C18:1 (∼2%), C18:2 (∼9.8%), and C18:3 (∼16.5%).

Extraction of lipids from a specialist dairy stream

In this work a process for the extraction of neutral and complex lipids from the specialist dairy stream ‘beta-serum’ is described. Beta-serum is a proprietary product obtained from dairy streams containing greater than 60% fat that have been through phase inversion from an oil-in-water to a water-in-oil emulsion. It is an enriched source of milk fat globular membrane proteins and complex lipids, and is distinct from buttermilk in this respect. In the process described here a total lipid extract could be obtained from liquid beta-serum using a continuous near-critical dimethyl ether (DME) antisolvent fractionation process. Protein and water are precipitated from solution when mixed with the DME, whilst lipid and some water are extracted into the DME-rich phase. The extraction yield of lipids depended on the solids content of the feed and the feed to DME flow ratio, but did not depend on the lactose content. Lipids were also extractable from spray dried beta-serum powder, but only when the lactose content had been reduced below 45% by mass. A two step extraction process is described in which neutral lipids are extracted with supercritical CO 2, and then polar lipids using near-critical DME. The polar lipid extract was enriched in phospholipids (∼70% by mass), which included phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and sphingomyelin. Other complex lipid components extracted included gangliosides and cerebrosides. Unlike the antisolvent process, proteins were not denatured during either CO 2 or DME processing of the spray dried powders, and the de-fatted powders are therefore suitable for a range of functional foods. A polar lipid extract could also be produced from spray dried powder by extracting first with DME to obtain a mixed neutral/complex lipid extract, then re-extracting the lipid extract with CO 2 to remove neutral lipids.

Optimization of Solvent Extraction and Direct Transmethylation Methods for the Analysis of Egg Yolk Lipids

The composition of egg yolk lipids differs greatly from most other food lipids, as it combines high contents of triglycerides and phospholipids, as well as a high proportion of cholesterol. The lipids are organized in lipoproteins and are dispersed in aqueous phase. Classical extraction methods using chloroform and methanol have not been optimized for such a matrix, therefore quantitative extraction yields of egg lipids can be inaccurate. In this study, the original method of Bligh and Dyer is evaluated and adapted for egg lipids. Furthermore, a direct extraction/derivatization method is presented. Solvent extraction resulted in a lipid yield of 31.8 ± 0.89% and total fatty acid yield was 257 ± 2 mg/g yolk whereas the direct method yielded 250 ± 7 mg/g yolk. Gas chromatographic analyses confirmed that lipid recovery was complete for triglycerides and phospholipids as well.

Supercritical carbon dioxide extraction of compounds with pharmaceutical importance from microalgae

Four microalgae ( Botryococcus braunii, Chlorella vulgaris, Dunaliella salina, Arthrospira maxima) were object of supercritical CO 2 extraction studies, which were carried out in a flow apparatus at temperatures between 313.1 and 333.1 K and pressures up to 35.0 MPa. The microalga Botryococcus braunii produces extracellular alkadienes. Supercritical extracts obtained at 313.1 K, and pressures of 12.5, 20.0 and 30.0 MPa, were golden and limpid, unlike those obtained with organic solvents. The hydrocarbons of this microalga were selectively extracted and this selectivity increased with pressure. The microalga Chlorella vulgaris is a carotenoid producer of canthaxanthin and astaxanthin. The extraction yields of lipids and carotenoids were compared for whole, crushed and slightly crushed algae at a pressure of 35.0 MPa and a temperature of 328.1 K. The yield of supercritical extraction of carotenoids was also compared at several conditions of pressure and temperature. It increased with pressure at constant temperature, remained practically constant with temperature, at pressures of 27.5 and 35.0 MPa, and decreased with temperature at 20.0 MPa. The third alga studied was the Dunaliella salina, which produces β-carotene in high yield. Natural β-carotene ( cis and trans mixture) from this alga was submitted to supercritical carbon dioxide and it was assessed, at pressures up to 30.0 MPa and temperature of 313.1 K, that both isomers presented higher solubility than the synthetic trans-β-carotene and that the cis isomer was much more soluble in supercritical CO 2 than the trans isomer. Moreover, it was shown that the cis/ trans ratio, in the supercritical extracts, increased significantly, relatively to the original one in the microalga, when the Dunaliella was submitted to supercritical CO 2. The cyanobacteria Arthrospira ( Spirulina) maxima can produce in large amounts the γ-linolenic acid (GLA), C18:3 ω6. The yield and selectivity of the supercritical extraction, using CO 2 and CO 2 doped with ethanol, of the lipids and GLA were determined and compared with those obtained with organic solvents.

Supercritical CO 2 extraction of carotenoids and other lipids from Chlorella vulgaris

Freeze-dried samples of the microalga Chlorella vulgaris were submitted to supercritical CO 2 at temperatures of 40 and 55 °C and pressures up to 35.0 MPa. This study was carried out on whole and crushed algae. The extraction yields of carotenoids and other lipids were low in the former case and improved significantly in the latter one. Extraction yields of carotenoids and other lipids increased with pressure. The fraction of carotenoids in the oil was also greater at higher pressures. On the other hand, supercritical CO 2 extraction of carotenoids compared favourably with hexane and acetone extractions.

Preparation of colorless sunflower protein products: Effect of processing on physicochemical and nutritional properties

AbstractA comparison was made of the different technological treatments for the preparation of colorless sunflower protein products from the viewpoint of the effect of processing conditions on the extraction yield of nitrogen and lipid, chemical, physicochemical and nutritional properties of the processed products. The technological treatments comprised soaking dehulled seeds in dilute citric acid or sodium bisulfite solution and washing the defatted meal with the respective solution. The defatting process was carried out with hexane or azeotrope (hexane/ethanol). Nitrogen and lipid recovery was slightly greater for hexane defatted products than for azeotrope defatted products. About 21.4% of the phenolic compounds of the sunflower seeds were bound to the proteins of the seeds before processing and therefore could not be eliminated by the aqueous extraction. Aqueous extraction of phenolic compounds was limited for full fat seed. The free phenolic compounds were very stable in acid medium but sensitive to oxidation in alkaline medium and had no significant effect on in vitro enzymatic proteolysis and growth inhibition of rats. Lysine and the bound phenolic compounds were the critical factors responsible for inhibition of enzymatic proteolysis and reduced growth of rats. The diet containing whole seed meal presented a low protein efficiency ratio (PER) value. Citric acid, a chelating agent, proved to be an antioxidant as effective as sodium bisulfite; the products obtained by citric acid treatment had a visually whiter color than those processed by sodium bisulfite.