Conjugated linolenic acid (CLnA), conjugated linoleic acid (CLA) and other biohydrogenation intermediates in plasma and milk fat of cows fed raw or extruded linseed

Thirty lactating dairy cows were used in a 333 Latin-square design to investigate the effects of a raw or extruded blend of linseed and wheat bran (70:30) on plasma and milk fatty-acids (FA). Linseed diets, containing 16.6% linseed blend on a dry-matter basis, decreased milk yield and protein percentage. They decreased the proportions of FA with less than 18 carbons in plasma and milk and resulted in cis-9, cis-12, cis-15 18:3 proportions that were more than three and four times higher in plasma and milk, respectively, whereas cis-9, cis-12 18:2 proportions were decreased by 10–15%. The cis-9, trans-11, cis-15 18:3 isomer of conjugated linolenic acid was not detected in the milk of control cows, but was over 0.15% of total FA in the milk fat of linseed-supplemented cows. Similarly, linseed increased plasma and milk proportions of all biohydrogenation (BH) intermediates in plasma and milk, including the main isomer of conjugated linoleic acid cis-9, trans-11 18:2, except trans-4 18:1 and cis-11, trans-15 18:2 in plasma lipids. In milk fat, compared with raw linseed, extruded linseed further reduced 6:0–16:0 even-chain FA, did not significantly affect the proportions of 18:0, cis-9 18:1 and cis-9, cis-12 18:2, tended to increase cis-9, cis-12, cis-15 18:3, and resulted in an additional increase in the proportions of most BH intermediates. It was concluded that linseed addition can improve the proportion of conjugated linoleic and linolenic acids, and that extrusion further increases the proportions of intermediates of ruminal BH in milk fat

Cis-15 intermediates of biohydrogenation in the duodenal flow of cows receiving linseed

Duodenal samples from a previous experiment (Akraim et al., 2006) were reanalysed for determination of cis-15 intermediates of ruminal biohydrogenation (BH). Three dry Holstein cows fitted with a duodenal cannula received a diet with 14% (dry matter basis) raw linseed. C18 fatty acids (C18FA) represented 6.3% of dietary dry matter, and contained 57.8% of C18:3. After 18 days adaptation, on each cow, twelve samples of duodenal flow were taken over 3 days, composited, and analysed for FA composition. Cis-9,trans-11,cis-15C18:3 and trans-11,cis-15C18:2 (CLnA) were identified by GC-MS. The proportion of CLnA was low, in spite of the high C18:3 intake. The first step of C18:3 BH, isomerisation to CLnA, was extensive because the C18:3 proportion was 13.5 times lower in the duodenum than in the diet (Akraim et al., 2006). The extensive C18:3 BH and the low proportion of CLnA suggest a rapid ruminal reduction of this FA. The proportion of the product of this first reduction, trans-11,cis-15C18:2, was much higher than that of CLnA, but quite variable among cows. This suggests that the reduction of this FA was slower than that of CLnA, although this reduction is supposed to be due to a broad range of bacteria. According to responsible bacteria, this reduction can lead to trans-11C18:1, or cis-15C18:1 and trans-15C18:1. Cis-15C18:1 represented only half the proportion of trans-15C18:1, suggesting either a direct BH of trans-11,cis-15C18:2 to trans-15C18:1, or a rapid isomerisation of cis-15C18:1 to trans-15C18:1

La Recherche des complications liées à l'alcool par le médecin généraliste (à propos d'une enquête auprès des médecins généralistes du pays d'Aix)

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Effets comparés, à très court terme, des acides n-9, trans-docosénoïque (brassidique) et n-9, cis-docosénoïque (érucique) sur les lipides cardiaques du rat sevré

National audienceCardiac lipids (triglycerides and phospholipids) of weanling rats fed diets containing 15 % by weight of rapeseed oil (RSO), hydrogenated rapeseed oil (HRSO), trierucin (TE) or tribassidin (TB) were analyzed after 3 and 7 days of feeding. The amount of C22:1 was made equal in the 4 diets. Tarns-isomers of erucic acid found in HRSO and TB do not cause as high an accumulation of lipids and docosenoic acids in the heart as erucic acid. Digestibility of brassidic acid (46 %) is lower than that or erucic acid (83 %) but even then, the amount of brassidic acid found in cardiac lipids (calculated per gram of absorbed fatty acid) after 7 days of feeding is 10 times less than that of erucic acid. Brassidic acid, like erucic acid, can be converted into shorter monoenes (C20:1 and C18:1) since trans-CIS :1 has been found in cardiac phospholipids of rats fed trans-docosenoic acid as the only source of trans-acid in the diet

Trans fatty acids: Definition and occurrence in foods

International audienceMost of fatty acid double bonds are in cis configuration, but some processes may isomerise double bonds from cis to trans configuration and from their naturally occurring positions in the carbon chain. Since some fatty acids with trans double bond(s) are suspected to have adverse effects, several countries have regulated the inclusion of trans fatty acid (TFA) content labelling. The French governmental authorities requested AFSSA to propose recommendations regarding food labelling. This first article summarises the discussion on a regulatory TFA definition and reviews the occurrence and origins of TFA in foods. From a chemical point of view, a TFA is any kind of fatty acid that has one or more double bond(s) in trans configuration, but restricted TFA definitions have been proposed for food labelling purposes. These definitions exclude fatty acids with conjugated double bonds on different criteria which are commented on in this paper. Taking into account the goal of TFA labelling and the potential harmful properties of some trans conjugated fatty acids, the working group proposes the chemical definition for TFA labelling purposes. The main TFA natural origin is ruminal biohydrogenation, and therefore TFA are present in dairy products and ruminant meat. TFA are also found in domestically or industrially processed foods due to hydrogenation or heat treatment effects on oils and fats. Although the TFA molecules produced by both natural and industrial processes are often quite similar, TFA distribution profiles and levels are very different from one case to another

Analytical methods for determination of trans fatty acid content in food

International audienceAdequate analytical tools are required for labelling food products for trans fatty acid (TFA) contents. The choice of the fatty acid (FA) derivatisation is a crucial step in obtaining good results, in particular with short-chain and conjugated FA. Several gas chromatographic and infrared spectrophometric methods have been developed for analysing TFA in foods, some of which have been validated as official methods after collaborative studies. Complete analysis of total FA often requires the use of complementary high-performance liquid chromatography methods. This paper reviews the analytical methods developed for identifying and quantifying TFA in foods and presents the official methods of analysis. Neither of these analytical methods enables a TFA naturally occurring in basic food to be distinguished from a TFA formed during an industrial process

CLA profile in native fat globules of different sizes selected from raw milk

The CLA content and isomer profile were characterized among two subclasses of the native milk fat globules. The latter corresponded to two fractions obtained by a microfiltration process using Spring mixed milk, leading to small fat globules (SFG; Click to view the MathML source) in the microfiltrates and large ones (LFG; Click to view the MathML source) in the retentates. Relatively, SFG always contained more CLA than the LFG originating from the same mixed milk, though discrepancies among different milk samples were observed. The main CLA isomer was the cis-9, trans-11, the content of which tended to increase when the native milk fat globule size decreased (from 82.2% to 87.3% of total CLA isomers). Consequently, the SFG contained less trans-12, trans-14; trans-11, trans-13; trans-11, cis-13 and trans-8, cis-10 isomers than the corresponding LFG. However, the relative variation of some isomers between small and large fat globule from the same milk varied depending on milk origin and the potential of fat globule fractionation for influencing the content and distribution of CLA seems to be limited

Variations of trans octadecenoic acid in milk fat induced by feeding different starch-based diets to cows

International audienc