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1.
This study examined the effects of feeding diets rich in either n-3 or n-6 polyunsaturated fatty acids (PUFA) on the fatty acid composition of longissimus muscle in beef bulls. Thirty-three German Holstein bulls were randomly allocated to either an indoor concentrate system or periods of pasture feeding (160 days) followed by a finishing period on a concentrate containing linseed to enhance the contents of n-3 PUFA and conjugated linoleic acids (CLA) in beef muscle. The relative proportion and concentration (mg/100 g fresh muscle) of n-3 fatty acids in the phospholipid and triglyceride fractions were significantly increased (p < or = 0.05) in muscle lipids of pasture-fed bulls. The pasture feeding affected the distribution of individual CLA isomers in the muscle lipids. The proportion of the most prominent isomer, CLA cis-9,trans-11, was decreased from 73.5 to 65.0% of total CLA in bulls fed on concentrate as compared to pasture. The second most abundant CLA isomers were CLA trans-7,cis-9 and CLA trans-11,cis-13 in bulls fed on concentrate and pasture, respectively. Diet had no effect on the concentration of C18:1 trans-11. In contrast, the concentration of the C18:1 trans-13/14, trans-15, and trans-16 isomers in the muscle lipids was up to two times higher in pasture-fed as compared to concentrate-fed bulls. Pasture feeding enhanced the concentration of n-3 fatty acids, but the diet had no effect on the concentration of CLA cis-9,trans-11.  相似文献   

2.
Rumelenic (cis-9,trans-11,cis-15 18:3) acid is a naturally occurring conjugated isomer of alpha-linolenic acid (CLnA) in milk fat. Metabolism in rats was studied using a synthetic CLnA mixture, composed mainly by equimolar quantities of cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15 CLnA isomers. Their metabolisms were studied by feeding high quantities of CLnA (150 mg/day) for 4 days to rats that had been reared on a fatfree diet for 2 weeks. After this period, animals were sacrificed and liver and epididymal adipose tissue lipids extracted. Six metabolites of the cis-9,trans-11,cis-15 18:3 CLnA isomers were identified as being cis-7,trans-9,cis-13 16:3, cis-11,trans-13,cis-17 20:3, cis-8,cis-11,trans-13,cis-17 20:4, cis-5,cis-8,cis-11,trans-13,cis-17 20:5, cis-7,cis-10,cis-13,trans-15,cis-19 22:5, and cis-4,cis-7,cis-10,cis-13,trans-15,cis-19 22:6 acids. Two metabolites of cis-9,trans-13,cis-15 18:3 CLnA isomer were also identified by GC-MS as being cis-7,trans-11,cis-13 16:3 and cis-5,cis-8,cis-11,trans-15,cis-17 20:5.  相似文献   

3.
Conjugated linoleic acid (CLA) is a naturally occurring micronutrient in milk fat and dairy products consisting of a group of geometric and positional isomers. The purpose of this study was to assess the level and type of CLA isomers found in two commercial processed cheeses (portions and slices) as well as to monitor their evolution during the different manufacturing stages. Total CLA concentrations ranged from 7.5 to 7.9 mg/g of fat, and rumenic acid (cis-9,trans-11 C18:2), the isomer responsible for the biological functions, represented >80% of total CLA. trans-11,cis-13 and trans-11,trans-13 were, with approximately 4% each, the second main CLA isomers. trans-trans isomers accounted for <10% of total CLA. The processing parameters used in this research had negligible effects on the CLA content of processed cheese and did not modify the isomer profile in these dairy products, thereby confirming the stability of rumenic acid during manufacturing.  相似文献   

4.
Saccharomyces cerevisiae was cultivated in the presence of cis-9,trans-11 or trans-10,cis-12 isomers of free conjugated linoleic acid (CLA), and the effects of the isomers on the regioisomerisms of triacylglycerol (TAG) of the yeast were elucidated. Both isomers constituted about 34% of all fatty acids and increased drastically the number of different TAG species. Nearly all of the species contained CLA in at least one sn-position. In the most abundant species analyzed (20% of total species), the cis-9,trans-11 isomer appeared in combination with monounsaturated fatty acids (C16:1, C:18:1) whereas trans-10,cis-12 isomer was most frequently present with a medium chain fatty acid (C10:0 or C12:0) in the sn-2 position and C16:0 in one of the end positions (14% of total species). With either isomer, the amount of TAG species in which CLA encompassed all sn-positions was ca. 4%. Thus, S. cerevisiae can be used to produce edible single cell oil characterized by very heterogeneous distribution of CLA among the different TAG species.  相似文献   

5.
The incorporation pattern of conjugated linoleic acids (CLA) isomers into the egg yolk of hens in relation to that in the diet was studied. Silver-ion high-performance liquid chromatography (Ag-HPLC) was used to separate individual CLA isomers. It was found that the isomeric distribution pattern in the egg yolk lipids was different from that in the dietary fat. Total cis/trans isomers accounted for 81.2% of total CLA incorporated into the egg yolk, which was in contrast to the value of 92.0% of total CLA in the diet. Total cis/cis isomers accounted for 3.8% total CLA in the diet but they were 6.6% of the total CLA in the egg yolk lipids. In contrast, total trans/trans isomers were 12.2% of the total CLA isomers in the egg yolk lipids, whereas they were only 4.2% of total CLA in the diet. The results showed that total trans/trans-CLA was preferentially incorporated into the egg yolk, whereas the incorporation of total cis/trans-CLA isomers was partially discriminated. Within each group, the incorporation of individual isomers into the egg yolk lipids was also selective. cis-9,trans-11/trans-9,cis-11 and cis-10,trans-12/trans-10,cis-12 were the two major isomers in the diet. Ag-HPLC analysis showed that the former was preferentially transferred into the egg yolk compared with the latter. It was observed that supplementation of CLA in the diet of laying hens decreased the concentration of oleic acid (18:1n-9), arachidonic acid (20:4n-6), and docosahexaenoic acid (22:6n-3) but increased that of linolenic acid (18:3n-3), stearic acid (18:0), and palmitic acid (16:0) in the egg yolk, suggesting that CLA may inhibit Delta6 and Delta9 desaturases.  相似文献   

6.
Stimulation of macrophages by a variety fatty acids causes activation of MAP kinases (MAPKs). The consequences arising from down-regulation of MAPKs may be a limitation in the activity of PPARγ, which is modulated by a modification catalyzed by these kinases. Phosphorylation of MAP kinases-ERK1/2 and p38 as well as PPARγ was determined by real-time polymerase chain reaction and Western blotting in human macrophages cultured with conjugated linoleic acids (CLAs). We demonstrated that CLA isomers alter MAP kinase phosphorylation and PPARγ activation. Phosphorylation of ERK1/2 was diminished in cells cultivated with cis-9,trans-11 CLA, whereas phosphorylation of p38 was reduced by trans-10,cis-12 CLA. PPARγ was phosphorylated mainly by ERK1/2, and consequently, PPARγ phosphorylation was suppressed mainly by cis-9,trans-11 isomer. In human adipocytes, cis-9,trans-11 C 18:2 raised the activation of PPAR and several of its downstream target genes. We suggest that a similar process may also occur in human macrophages.  相似文献   

7.
The fatty acid profile of the subcutaneous fat of pigs and its evolution throughout fattening as affected by dietary conjugated linoleic acid (CLA), monounsaturated fatty acids (MUFA), and their interaction (CLAxMUFA) were studied. Three levels (0, 1, and 2%) of an enriched CLA oil (28% cis-9, trans-11 and 28% trans-10, cis-12 CLA) were combined with two levels of MUFA (low, 19% average; and high, 39% average) for pig feeding (288 gilts). Subcutaneous shot-biopsies were taken from 48 animals at the beginning of the trial (S1, 70 kg), 14 days later (S2, 80 kg), and at slaughter (S3, 107 kg). Inclusion of CLA in the diet caused an increase during fattening in cis-9, trans-11 CLA, trans-10, cis-12 CLA, and saturated fatty acids (SFA) contents of pig backfat and a decrease in MUFA and polyunsaturated fatty acids (PUFA). MUFA supplementation also led to a MUFA enrichment of backfat. The interaction CLAxMUFA affected the SFA content. The rates of accumulation of CLA isomers, SFA, and MUFA throughout the trial did not follow a linear behavior, such rates being higher from S1 to S2 than from S2 to S3. These rates were also influenced by dietary CLA and MUFA levels. The increase in the ratio of saturated to unsaturated fatty acids of backfat caused by dietary CLA might be balanced by supplementation of pig diets with MUFA.  相似文献   

8.
The isomeric distribution of conjugated linoleic acids (CLA) in the tissue lipids of hens in relation to that in the diet was examined. Silver-ion high-performance liquid chromatography was used to quantify individual CLA isomers in total tissue lipids, phospholipids, and triacylglycerols. It was found that the deposition of CLA isomers in hen tissues was selective. All tissues including serum, liver, heart, kidney, abdominal fat, and leg and breast muscles had lesser amounts of total cis/trans isomers ranging from 75.87 to 89.13% of total CLA, which was in contrast to the value of 92% of total CLA in the dietary lipids. Total trans/trans isomers in all tissue lipids ranging from 6.11 to 18.02% of total CLA were greater than that in the diet (4.19%). Among the individual trans/trans isomers, all tissues except for adipose tissue and brain incorporated greater amounts of t-12,t-14-18:2, t-11,t-13-18:2,t-10,t-12-18:2, t-9,t-11-18:2, and t-18,t-10-18:2 compared with the values of the diet. Within the cis/trans group, lesser amounts of c-10,t-12/t-10,c-12-18:2 were found to incorporate into all tissues compared with the value of the diet. Serum and liver had higher percentages of c-9,t-11/t-9,c-11, whereas the other tissues had similar levels of this isomer compared with that of the diet. It was also observed that supplementation of CLA in the diet of layer hens decreased the concentration of docosahexaenoic acid (22:6n-3) in all of the tissue lipids. It is concluded that dietary CLA can transfer to the tissue but that incorporation of CLA isomers into the tissue is selective in hens.  相似文献   

9.
Three groups of double-muscled Belgian Blue young bulls were fed during different stages of production diets differing in the proportions of linolenic and linoleic acid by including linseed in the concentrate or giving grass silage as main linolenic acid suppliers. Samples of rumen and abomasal contents and of the longissimus thoracis, subcutaneous fat, and liver were taken to analyze the fatty acid pattern with emphasis on the individual trans (t) C18:1 fatty acids and cis-9,trans-11 conjugated linoleic acid (c9t11CLA). Trans C18:1 isomers represented up to 20 g/100 g of total fatty acids in rumen and abomasal contents, whereas the accumulation of c9t11CLA was limited. Total trans C18:1 content in subcutaneous fat and intramuscular fat of the longissimus thoracis comprised 8.4 and 5.2 g/100 g of total fatty acids, respectively, with t11C18:1 being the most abundant one. Compared to rumen contents, subcutaneous and intramuscular fat were enriched in c9t11CLA and contained fewer tC18:1 isomers, resulting in a higher c9t11CLA/t11C18:1 ratio (0.04, 0.22, and 0.22, respectively). This result suggests that the endogenous synthesis of c9t11CLA in adipose tissue by the Delta(9)-desaturase was more important than its ruminal production.  相似文献   

10.
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11.
A conjugated linoleic acid (CLA)-rich soy oil has been produced by photoisomerization of soy oil linoleic acid. Nutritional studies have shown that CLA possesses health benefits in terms of reducing certain heart disease and diabetes risk factors. Potato chips are snacks that are readily produced in the CLA-rich soy oil containing CLA levels similar to those of the oil used for frying. The objective of this study was to develop an FTIR method to rapidly determine the CLA content of oil in potato chips. Photoirradiated soy oil samples with ～25% total CLA were mixed with control soy oil, and 100 soy oil samples with total CLA levels ranging from 0.89 to 24.4% were made. Potato chips were fried using each of these 300 g CLA rich soy oil mixtures at 175 °C for approximately 3 min. Duplicate GC-FID fatty acid analyses were conducted on oil extracted from each batch of potato chips. The chip samples were ground and then scanned using ATR-FTIR spectroscopy with the aid of a high-pressure clamp, and duplicate spectra of each sample were averaged to obtain an average spectrum. Calibration models were developed using PLS regression analysis. These correlated the CLA isomer concentrations of potato chips obtained by GC-FID fatty acid analysis with their corresponding FTIR spectral features. The calibration models were fully cross validated and tested using samples that were not used in the calibration sample set. Calibrations for total CLA, trans,trans CLA, trans-10,cis-12 CLA, trans-9,cis-11 CLA, cis-10,trans-12 CLA, and cis-9,trans-11 CLA had coefficients of determinations (R2v) between 0.91 and 0.96 and corresponding root-mean-square error of prediction (RMSEP) ranging from 0.005 to 1.44. The ATR-FTIR technique showed potential as a method for the determination of the CLA levels in unknown potato chip samples.  相似文献   

12.
The feasibility of Raman spectroscopy in combination with partial least-squares (PLS) regression for the determination of individual or grouped trans-monounsaturated fatty acids (trans-MUFA) and conjugated linoleic acids (CLA) in milk fat is demonstrated using spectra obtained at two temperature conditions: room temperature and after freezing at -80 °C. The PLS results displayed capability for direct semiroutine quantification of several individual CLA (cis-9,trans-11 and trans-10,cis-12 C18:2) and trans-MUFA (trans-4-15 C18:1) in minor concentrations (below 1.0 g/100 g of milk fat). Calibration models were based on reference data cross-correlation or determined by specific scattering signals in the Raman spectra. Distinct bands for trans-MUFA (1674 cm(-1)) and CLA (1653 cm(-1)) from the trans isolated and cis,trans conjugated C ═ C bonds were identified, as well as original evidence for the temperature effect (new bands, peak shifts, and higher intensities) on the Raman spectra of fatty acid methyl ester and triacylglyceride standards, are supplied.  相似文献   

13.
Although studies have been performed to test whether conjugated linoleic acid (CLA) acts as an antioxidant, the results were not conclusive. In addition, the CLA widely used in previous research contains 43% cis-9,trans-11 isomer, 45% trans-10,cis-12 isomer, and 10 other minor isomers. The objective of this study was to investigate the antioxidant activity of cis-9,trans-11- and trans-10, cis-12-CLA isomers using high-purity CLA isomers (>98%) by total oxyradical scavenging capacity assay (Winston, G. W.; Regoli, F.; Dugas, Jr., A. J.; Fong, J. H.; Blanchard, K. A. Free Radical Biol. Med. 1998, 24, 480-493). At all concentrations (2-200 microM), t10, c12-CLA performed as an antioxidant with a 15-min lag phase, which was more effective than c9,t11-CLA and alpha-tocopherol at lower concentrations (2 and 20 microM). On the other hand, c9,t11-CLA possessed weak antioxidant activity at 2 and 20 microM, whereas at 200 microM it acted as a strong pro-oxidant, which suggests that discrepancies of the results of the previous studies on the antioxidant properties of CLA may be due to the balance of the antioxidant properties of t10,c12-CLA and the pro-oxidant properties of c9,t11-CLA in different oxidation conditions.  相似文献   

14.
Conjugated linoleic acid in canadian dairy and beef products.   总被引：9，自引：0，他引：9  
Conjugated linoleic acid (CLA) is a dietary fatty acid produced by ruminant animals and exhibits promising beneficial health effects. CLA has been identified as having anticancer, antiatherogenic, and body fat reducing effects. There are no published data on the CLA content of Canadian beef and dairy products. The purpose of this study was to assess the level and type of CLA isomers found in commercial beef and dairy products. Under the present experimental conditions only the Delta9c,11t-18:2 isomer was detected. Other minor isomers, which may be present, were not determined by the method used in this study. Levels of CLA ranged between 1.2 and 6.2 mg/g of fat or 0.001-4.3 mg/g or mg/mL of sample. On the basis of a usual serving size, levels of CLA ranged between 0.03 and 81.0 mg per serving. It is concluded that the Delta9c,11t-18:2 isomer is present in dairy and beef products and levels when expressed per gram of fat are not significantly different among products.  相似文献   

15.
A method for microbial isomerization of oat linoleic acid to conjugated linoleic acid (CLA) was developed. The method includes hydrolysis of oat lipids in aqueous flour slurries by the endogenous oat lipase. Then, the flour slurry containing free linoleic acid is utilized as a substrate for the isomerization reaction carried out by resting cells of Propionibacterium freudenreichii ssp. shermanii. The isomerization reaction progressed most effectively when, after the lipid hydrolysis period, the pH of the slightly acidic oat slurry was elevated to 8.0-8.5 and maintained at this range. With slurries containing 5% (w/v) oat flour, the amounts of CLA formed per dry matter were up to 10.1 mg/g corresponding to 102 mg/g lipids or 0.44 mg/mL slurry. Increments in the flour content up to 15% increased the volumetric production of CLA to 0.85 mg/mL. The proportion of the cis-9,trans-11 isomer was 80% of the total CLA formed. CLA could be concentrated into the solid material of the oat slurry by acidification.  相似文献   

16.
The objective of this investigation was to provide a comprehensive analysis of the total lipid composition of present-day retail beef meat available at the consumer level and to evaluate the total lipid composition with special emphasis on the nutritional value. For this purpose, 40 beef cuts were obtained from four cattle farms based on either a natural grazing system (NGS) or an intensive production system (IPS). The total lipid composition was analyzed using complementary chemical and chromatographic procedures. The content of n-3 LC-PUFA, CLA, total trans-18:1, and branched-chain fatty acids was significantly higher in NGS beef than in IPS beef. The trans-18:1 and CLA profiles were affected by the different production systems, whereby they can be utilized empirically to differentiate between feeding regimen and production management. Fatty acid ratios that have health implications ( n-6/ n-3, LA/alphaLNA, and AA/EPA) were remarkably beneficial for NGS beef compared with IPS beef. In conclusion, from the human health perspective, beef raised on NGS is clearly superior with regard to a more favorable fatty acid profile in comparison to IPS beef.  相似文献   

17.
The collective term "conjugated linoleic acid" or "CLA" generally refers to a mixture of conjugated positional and geometric isomers of linoleic (cis-9,cis-12-octodecadienoic) acid. In nature, these isomers are mainly formed in the rumen by biohydrogenation of polyunsaturated fatty acids. This study concerns a first trial of CLA determination in cow's milk fat by Raman spectroscopy. The spectra of pure cis-9-oleic, cis-9,cis-12-linoleic, cis-9,trans-11-linoleic, and trans-10,cis-12-linoleic acids have been examined in comparison with the spectra of selected milk-fat samples containing between 0 and 3% of CLA. The trial of CLA determination by Raman spectroscopy on cow milk fat has reached its objective with the two following results. First, the examination of the Raman spectra allows to identify three specific Raman signals of the chemical bonds associated to the cis,trans conjugated C=C in the rumenic and trans-10,cis-12-octodecadienoic acids at 1652, 1438, and 3006 cm(-1). Second, the calibration of Raman spectrometer for the CLA determination has indicated that these three specific signals suit very well for the accurate and reliable measurement of CLA concentration in milk fat. To our knowledge, the present study is the first successful attempt to determine the CLA content of milk fat by a spectrophotometric method.  相似文献   

18.
The esterified fatty acid composition of cheese (YC) from yak ( Bos grunniens), reared in the highlands of the Nepalese Himalayas, was studied using capillary gas-liquid chromatography and compared with that of dairy cow Cheddar cheese (DC) purchased in a local market. The YC was collected from Dolakha, Nepal. The YC had a lower (P<0.001) myristic acid (C14:0; 6.7 vs 10.3%, YC vs DC, respectively) and palmitic acid content (C16:0; 23.3 vs 29.2%, YC vs DC, respectively) compared to DC. The YC had a lower (P<0.01) total medium-chain saturated fatty acids (C10:0-C16:0) content compared to DC (36.7 vs 47.3%, YC vs DC, respectively). On the other hand, the YC had a 24.8% higher (P<0.01) level of total long-chain saturated fatty acids (C17:0-C26:0) and a 3.2 times higher (P<0.001) content of total n-3 PUFA than DC. The ratio of n-3 PUFA to n-6 PUFA in YC was 0.87 compared to 0.20 in DC. YC had a 2.8 times higher (P<0.001) total trans-18:1 (9.18 vs 3.31%, YC vs DC, respectively) content. The percentage of vaccenic acid ( trans-11-C18:1) in YC was 4.6 times higher (6.23 vs 1.35% of total fatty acids, YC vs DC, respectively) than in DC. Vaccenic acid constituted 67.9% of total trans-C18:1 in YC. The Delta9-desaturase index for YC was lower than that of DC. The total conjugated linoleic acid (CLA) content in YC was 2.3% of total fatty acids compared to 0.57% in DC. The cis-9, trans-11 CLA isomer in YC constituted 88.5% of the total CLA. The results suggest that cheese from yak, grazed on Himalayan alpine pastures, may have a more healthful fatty acid composition compared to cheese manufactured from dairy cattle fed grain-based diets.  相似文献   

19.
Four different methods for methylating conjugated linoleic acid (CLA) were compared. The HCl/MeOH and BF(3)/MeOH methods were tested under different time and temperature combinations. Increasing temperature and/or incubation time for either method decreased the cis-9,trans-11 and trans-10,cis-12 isomers, but trans-9,trans-11/trans-10,trans-12 isomers and artifacts (allylic methoxide) were increased. In addition, the triacylglyceride form of CLA was tested using the above methods and NaOMe at various temperatures for 20 min. The NaOMe did not generate methoxy artifacts. However, there were impurities in GC after methylation with NaOMe as well as with BF(3)/MeOH. The (trimethylsilyl)diazomethane method, which is a mild and easy alternative, was tested. Free forms of fatty acids were easily, but not completely, methylated by this method. Also, the method generated artifacts (trimethylsilyl CLA esters) and impurities (trimethylsilyl) that would interfere with short-chain fatty-acid analysis by GC.  相似文献   

20.
Lipoxygenases are a family of non-heme enzyme dioxygenases. The role of lipoxygenases is synthesis of hydroperoxides of fatty acids, which perform signaling functions in the body. Studies on conjugated linoleic acids (CLAs) as fatty acids with a potential anti-atherosclerotic function have recently been initiated. The aim of the study was to test the effect of CLAs and linoleic acid on 5- and 15-lipoxygenase (5-LO, 15-LO-1) enzyme activity, their mRNA expression, and concentration in the cells. It was also desired to determine whether the CLAs are substrates for the enzymes. For the experiments monocytic cell line (THP-1) and monocytes obtained from human venous blood were used. Monocytes were differentiated to macrophages: THP-1 (CD14+) by PMA administration (100 nM for 24 h) and monocytes from blood (CD14+) by 7-day cultivation with the autologous serum (10%). After differentiation, macrophages were cultured with 30 microM CLAs or linoleic acid for 48 h. The 15- and 5-lipoxygenase products were measured by HPLC method. mRNA expression and protein content were analyzed by real-time PCR and Western blot analysis. The in vitro studies proved that both CLA isomers are not substrates for 15-LO-1; in ex vivo studies hydroxydecadienoic acid (HODE) concentration was significantly reduced (p = 0.019). The trans-10,cis-12 CLA isomer reduced HODE concentration by 28% (p = 0.046) and the cis-9,trans-11 CLA isomer by 35% (p = 0.028). In macrophages obtained from THP-1 fatty acids did not change significantly mRNA expression of the majority of the investigated genes. CLAs did not change the content of 5-LO and 15-LO-1 proteins in macrophages obtained from peripheral blood. Linoleic acid induced 15-LO-1 expression (2.6 times, p < 0.05). CLAs may perform the function of an inhibitor of lipoxygenase 15-LO-1 activity in macrophages.  相似文献   

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