Current techniques of extraction, purification, and preliminary, fractionation of polar lipids of natural origin

Outdoor cultivation of the green microalga Chlorella vulgaris under stress conditions as a feedstock for biofuel

The present work investigated the potential of the green alga Chlorella vulgaris to produce high-quality biofuel under culture stress conditions. The cultivation was carried out in a 1000 l open plate tank system, which provides biomass yields comparable to open pond systems, but with less area needed. Algal biomass and lipid content were measured repeatedly. We compared the two solvent systems n-hexane and hexane/isopropanol (HIP) for extraction efficiency of lipids and applied three different extraction methods Soxhlet, soaking, and soaking followed by Soxhlet (soak-Sox). The combination of the HIP solvent and the soak-Sox provided the highest lipid yield (15.8 ± 0.174). Volumetric biomass and lipid productivity were 0.201 g l^-1 day^-1 and 31.71 mg l^-1 day^-1, respectively, whereas areal biomass and lipid productivity were 25.73 g m^-2 day^-1 and 4.066 g m^-2 day^-1, respectively. The fatty acid profile by means of gas chromatography resulted in seven fatty acids from C₁₂ to C₁₈. The most abundant fatty acid methyl esters (FAMES) were palmitic (C16:0), oleic (C18:1), and stearic (C18:0) acids. Lipid synthesis enhanced by optimizing the Kuhl growth medium with replacing nitrate by urea (50% N compared to the original recipe) increased salt content (10 g/l NaCl), ferrous sulfate (0.5 g/l), and sodium acetate addition (1 g/l). With regard to density, kinematic viscosity, gravity, pour point, flash point, and cetane number, the Chlorella-biodiesel comply with ASTM and EN standards thus pointing at the high potential of lipids synthesized by Chlorella as a feedstock for biodiesel production.

Isolation of chlorinated fatty acid methyl esters derived from cell-culture medium and from fish lipids by using an aminopropyl solid-phase extraction column

An aminopropyl-based solid-phase extraction technique was used for isolation of chlorinated fatty acids in lipids. A range of different chlorinated fatty acids was eluted in a small volume of solvent (4 ml) and the recoveries of the different species and isomers were quantitative. Only 1% of the vastly dominating unchlorinated fatty acid methyl esters were recovered in the fractions containing the chlorinated fatty acid methyl esters. This method makes it possible to isolate and detect > or = 1 microg of a chlorinated fatty acid methyl ester in 1 g of lipid.

Downstream processing of algal polyunsaturated fatty acids

Little information exists on recovering polyunsaturated fatty acids from microalgae; however, methods for concentration and purification of PUFAs from fish oil have been extensively reported. This review examines recovery and purification of microalgae derived PUFAs, but techniques developed for use with fish oil are also reviewed as being potentially useful for concentration and purification from microalgae. The two main techniques for concentrating and purifying-urea fractionation and high performance liquid chromatography-are discussed in depth and attention is focused on the process developed by the authors for obtaining highly pure PUFA. Other potentially useful techniques, such as supercritical fluid extraction and lipase-catalyzed processing are detailed.

Algal phospholipids by 31P NMR: comparing isopropanol pretreatment with simple chloroform/methanol extraction

1. A modified Folch procedure [potassium (ethylenedinitrilo)-tetraacetic acid at pH 6 substituted for KCl] is suitable for the extraction of marine algae. 2. The quantitative 31P nuclear magnetic resonance phospholipid profiles of four marine algae, Gracilaria verrucosa, Bryothamnion triquetrum, Padina gymnospora, and Caulerpa sertularioides, were obtained from Folch and Nichols extractions of both fresh and dried algae, and essentially identical results were obtained using either extraction procedure. 3. Extracts of air-dried algae are statistically different when compared to extracts of living algae, suggesting that tissue handling is a critical factor in phospholipid extractions.

Effects of exercise training on diet-induced lipogenic enzymes and body composition in rats

It is well known that a carbohydrate-rich diet promotes lipogenesis via induction of hepatic lipogenic enzymes, whereas chronic physical exercise reduces body fat. The purpose of this study was to investigate whether exercise training can decrease diet-induced hepatic lipogenic enzymes and total body fat composition. Female Sprague-Dawley rats were randomly divided into exercise trained (T) and sedentary (S) groups. Training was performed on a treadmill for 8 weeks for up to 25 m/minute, 15% grade for 90 minutes/day, 5 days/week. The T and S groups were further divided into four dietary treatments. Fifty percent of the calories for each diet were from a basal ingredient and the other 50% were from either cornstarch (C), glucose (G), fructose (Fr), or fat (Fa). T significantly decreased body fat and increased body water content in all dietary groups (p < 0.01), but had no effect on body weight. Fr rats had significantly heavier liver weight than did the remaining groups. Activities of hepatic fatty acid synthase, ATP-citrate lyase (CL), malic enzyme (ME), pyruvate kinase, and glucose-6-phosphate dehydrogenase were significantly higher in Fr and lower in Fa compared with C and G. Training significantly increased activities of CL and ME in Fa, but had little effect on these enzymes in other groups. These data suggest that the fat-reducing effect of conventional exercise training is elicited by regulatory mechanisms other than by a reduction of hepatic lipogenic enzymes.

Yolk lipids

The mature egg yolk of the domestic hen possesses remarkably constant lipid and lipoprotein composition despite much variation in dietary and environmental conditions. The greatest differences are seen in the fatty acid composition of the triacylglycerols which may show significant alterations in the content of the minor acids including certain polyunsaturated acids. The lipid class composition appears to be minimally affected by dietary influences, including the cholesterol content of the diet. The limited dietary influence on the yolk lipid composition extends to different strains of the hens. Genetic selection has led to some increase in the cholesterol content of the egg, but the desired lowering of the cholesterol content of egg yolk has not been realized. Likewise, production of a polyunsaturated fatty acid egg does not appear to be practical. As a result the egg yolk continues to provide a food product of nearly constant composition, which serves to maintain its chemical and physico-chemical properties for reliable utilization in the baking, cosmetic and pharmaceutical industries. The great uniformity in the composition of the egg yolk phospholipids makes them desirable starting materials for partial chemical resynthesis of glycerophospholipids. Partial hydrogenation of the egg yolk lipids promises to further increase the utility of the product as a desirable material for the manufacture of liposomes and liposome based drug products. In contrast, the constancy of the egg yolk composition and the inability to alter it significantly by dietary or genetic means also renders egg yolk undesirable for unlimited human consumption. Excessive ingestion of egg yolk raises plasma lipid and cholesterol levels which are believed to contribute to the development of heart disease. The physico-chemical and biological properties of egg yolk apoproteins have been less extensively investigated and their function is less well understood. The finding that phosvitin is a effective chelator of metal ions and thus an effective antioxidant demonstrates that egg yolk lipoproteins possess as yet unexplored potential for beneficial nutritional, medical and industrial application.

Separation of phospholipids in bovine tissue with disposable silica gel extraction columns

A simple and elegant method using disposable silica gel columns has been developed to separate the phospholipid fraction in beef muscles from other fatty acid containing lipids. By this method, 10 samples can be cleaned up simultaneously in less than 2 h. It does not require complicated equipment. The separation of the phospholipid fraction is necessary in order to characterize it by chemical means, for instance to determine the fatty acid pattern. Recovery and reproducibility were proved with a model meat system. Purity was proved with a model system and biological samples.

A comparison of three methods of soft ionization mass spectrometry of crude phospholipid extracts

Many different classes of phospholipids were identified from crude extracts of hearts by three soft ionization mass spectrometric techniques: liquid matrix secondary ion mass spectrometry in the negative mode, (-)LSIMS, and in the positive mode, (+)LSIMS, and field desorption. (-)LSIMS and (+)LSIMS are complementary methods. In some cases it was possible to establish the fatty acid and aldehyde composition and position of some phospholipid classes, by the analysis of fragments.