Fatty acid composition, cholesterol content and lipid oxidation indices of intramuscular fat from skeletal muscles of beaver (Castor fiber L.)

The lipid characteristics of the intramuscular fat (IMF) from skeletal muscles of different beaver carcass parts (the loin, hind leg and shoulder) were characterised in detail for the first time. The shoulder muscles had higher (P < 0.05) proportion of n-3 polyunsaturated fatty acids (PUFA) than the loin muscles, which had higher percentages of saturated fatty acids (SFA), odd-chain fatty acids (OCFA) and sum of conjugated linoleic acids (ΣCLA). Moreover, the shoulder muscles were found to contain higher fat, cholesterol and total fatty acids (FA) concentrations, as well had a beneficial fatty acid profile, especially in terms of the absolute content of PUFA and some nutritional FA indices (thrombogenic index and SFA/PUFA), as well as FA ratios (n-6/n-3 and PUFA/SFA). No differences (P > 0.05) in lipid oxidation parameters (FFA, PV and TBARS) were observed between muscles from different carcass parts. Irrespective of muscle location, the predominant class of FA in IMF of beaver was PUFA (averaging 49.39%), followed by SFA (27.81%) and MUFA cis (15.96%). Linoleic acid (LA, 18:2 n-6) was the most abundant FA in all muscles (>34% of total FA). Minor percentages of unusual FA (OCFA, trans FA and branched-chain FA), which are more typical for ruminants than monogastric animals, were also detected (3.46%, 1.92% and 1.22%, respectively).

Analysis of trans fatty acids production and squalene variation during amaranth oil extraction

The purpose of this study was to evaluate the decay of squalene and the formation of trans fatty acids (TFAs) in the amaranth oil extracted with hexane with and without heat. Oils were analyzed by determining their chemical values, and the fatty acids were identified and quantified by using Fourier-transform infrared (FTIR) spectroscopy, in the mid-region of 400–4000 cm−1, and gas chromatography. The FTIR analysis shows that two oil extracts (with and without heat) present a well-defined peak at 968 cm−1, which represents the trans double bonds. The quantified TFAs are

Isolation and optimisation of the oleaginous yeast Sporobolomyces roseus for biosynthesis of 13C isotopically labelled 18-carbon unsaturated fatty acids and trans 18:1 and 18:2 derivatives through synthesis

An oleaginous and psychrotrophic strain (F38-3) of Sporobolomyces roseus Kluyver & van Niel was isolated from a salt marsh environment in Nova Scotia, Canada following a screening program to select for high producers of 18-carbon unsaturated fatty acids. Fatty acid production was characterised as a function of temperature at 20 g glucose L−1, and optimal yields were obtained at 14°C, achieving 5.7 g dw biomass and 39.2% total fatty acids by dry weight, with 18:1, 18:2 and 18:3 all-cis fatty acids accounting for 49.4%, 14.3% and 6.7% of total fatty acids (TFA), respectively—the highest reported for this species. Production of 18:3 was inversely correlated to growth temperature, rising from 2% of TFA at 30°C to 8.9% at 6°C. Cultivation of isolate F38-3 on universally 13C (U-13C) labelled glucose and subsequent transesterification and isolation of the fatty acid methyl esters (FAMEs) by preparative chromatography yielded pure, highly 13C-enriched (&gt;90%) 18:1, 18:2 and 18:3 all-cis FAMEs. The U-13C 18:1 FAME was catalytically converted to U-13C 18:1 trans-9 and purified to &gt;99.5% purity. The U-13C 18:2 was converted by alkaline isomerisation into a 50/50 mixture of 18:2 cis-9, trans-11 and 18:2 trans-10, cis-12 isomers and purified to &gt;95.0% purity. Overall, 10%, by weight, of labelled glucose fed to isolate F38-3 was recovered as fatty acid methyl esters and 7.5% as 18-carbon unsaturated fats, and the final isomerisation reactions resulted in yields of 80% or greater. The ultimate goal of the work is to develop methodologies to produce 13C-labelled metabolic tracers as tools to study the metabolism of trans fats.

Comparison of Phosphatidylcholine Vesicle Properties Related to Geometrical Isomerism†

Glycerophosphatidylcholine containing trans-unsaturated fatty acid residues was prepared by reaction of the corresponding naturally occurring cis lipid with photochemically generated thiyl radicals. This modified lipid was chosen as the simplest model for gaining some insights of the complex scenario of membrane formation, in connection with the role of lipid geometry and the predominance of cis lipids in eukaryotic cells. The critical aggregation concentration for the spontaneous formation of vesicles was determined for cis and trans isomers with cis-parinaric acid used as a fluorescent probe and it was found to be similar for both lipids. Vesicle dimensions were investigated by light scattering and electron microscopy, and the type of fatty acid residues influenced the vesicle diameter, with a decrease along the series cis > trans > saturated. Fluorescence measurement of dye release from trans and cis vesicles showed also a different permeability. A picture emerged of the geometrical isomer preference in cells as a process driven by natural selection during the life evolution of different organisms, both in terms of compartment dimensions and membrane functionality.

Trans and positional ethylenic bonds in two dominant isomers of eicosapentaenoic acid from the freshwater sponge Baicalospongia bacillifera

Reinvestigation of the current FA composition of the regional freshwater sponge Baicalospongia bacillifera showed that the main measured isomer of EPA (14% of the total FA now detected) is, in fact, an unusual 5Z,8Z,11Z,14Z,18E-EPA. Two other isomers of this acid also present were identified as a novel 5Z,8Z,11Z,15Z,18E-EPA and the common methylene-interrupted 5Z,8Z,11Z,14Z,17Z-EPA (usually written simply as EPA). Isolation of these acids as their methyl ester derivatives was accomplished with the use of a combination of silver-ion column chromatography and HPLC. The structure of the two new compounds was deduced from GC-MS and detailed NMR data. Partial hydrazine reduction of all three isolated EPA esters followed by separation of cis/trans isomers of the resulting monoenoic acids and GC-MS analysis of their dimethyl disulfide adducts were used for determination of the configuration and position of the double bonds. We may assume that the sponge B. bacillifera cannot receive these unusual EPA isomers directly from food sources (e.g., algal diatoms), and accordingly restructuring of ordinary EPA to novel acids may take place in the sponge tissue.

Trans- and cis-octadecenoic acid isomers in the hump and milk lipids from Camelus dromedarius

The distribution profiles of individual trans- as well as cis-18:1 isomers from the fat prepared from the hump adipose tissue and the milk from Camelus dromedarius (the single-humped Arabian species) are described. Gas-liquid chromatography on two capillary columns with different polarities and lengths were used for this purpose in combination with argentation thin-layer chromatography. A comparison of the profiles established is made with that of true ruminant fats. In the fats from the dromedarius as well as from true ruminants, the trans-18:1 isomers have their ethylenic bonds in all positions between delta4 and delta16. The prominent trans isomer is the 11-18:1 (vaccenic) acid in all species, and the complete distribution profiles are quite similar. Concerning the cis isomers, the prominent isomer is oleic acid, followed by cis-vaccenic acid, as in true ruminant fats. Other cis isomers encompass the delta6-8 and the delta12 to delta15 isomers. Camelidae (suborder Tylopoda) and Bovidae (suborder Ruminantia) have evolved independently since the Eocene, that is for approximately 50 million years. Despite this considerable period, and the profound differences in anatomy, morphology, physiology, ecological and dietary habits between the extant species of these suborders, the rumen microflora has continued to synthesize the same trans- and cis-octadecenoic acid isomers, in comparable proportions, at least as deduced from their composition profiles. We conclude that the trans-18:1 acid profile is not intrinsically species-dependent, but it can be affected by the nature and the proportions of dietary unsaturated fatty acids that themselves depend on the feed, and that may be species-specific.

Biosynthesis of conjugated linoleic acid in humans

This paper deals with the reanalysis of serum lipids from previous studies in which deuterated fatty acids were administered to a single person. Samples were reanalyzed to determine if the deuterated fatty acids were converted to deuterium-labeled conjugated linoleic acid (CLA, 9c,11t-18:2) or other CLA isomers. We found 11-trans-octadecenoate (fed as the triglyceride) was converted (delta9 desaturase) to CLA, at a CLA enrichment of ca. 30%. The 11-cis-octadecenoate isomer was also converted to 9c,11c-18:2, but at <10% the concentration of the 11t-18:1 isomer. No evidence (within our limits of detection) for conversion of 10-cis- or 10-trans-octadecenoate to the 10,12-CLA isomers (delta12 desaturase) was found. No evidence for the conversion of 9-cis,12-cis-octadecadienoate to CLA (via isomerase enzyme) was found. Although these data come from four single human subject studies, data from some 30 similar human studies have convinced us that the existence of a metabolic pathway in one subject may be extrapolated to the normal adult population.