Levels Of Conjugated Linoleic Acid Research Articles

Genetic and functional aspects of linoleate isomerase in Lactobacillus acidophilus

While the remarkable health effects of conjugated linoleic acid (CLA) catalyzed from alpha-linoleic acid by the enzyme linoleate isomerase (LI, EC 5.2.1.5) are well recognized, how widely this biochemical activity is present and the mechanisms of its regulation in lactic acid bacteria are unknown. Although certain strains of Lactobacillus acidophilus can enrich CLA in fermented dairy products, it is unknown if other strains share this capacity. Due to its immense economic importance, this work aimed to investigate genetic aspects of CLA production in L. acidophilus for the first time. The genomic DNA from industrial and type strains of L. acidophilus were subjected to PCR and immunoblot analyses using the putative LI gene of L. reuteri ATCC 55739 as probe. The CLA production ability was estimated by gas chromatography of the biomass extracts. The presumptive LI gene from L. acidophilus ATCC 832 was isolated and sequenced. The resulting sequence shared 71% identity with that of L. reuteri and at least 99% with reported sequences from other L. acidophilus strains. All the strains accumulated detectable levels of CLA and tested positive by PCR and immunoblotting. However, no apparent correlation was observed between the yields and the hybridization patterns. The results suggest that LI activity might be common among L. acidophilus and related species and provide a new tool for screening potential CLA producers.

Diet and plasma evaluation of the main isomers of conjugated linoleic acid and trans-fatty acids in a population sample from Mediterranean north-east Spain

The aim of the present study was to describe the dietary pattern of a representative sample of 516 adult participants (203 men and 313 women) from Catalonia, a Spanish Mediterranean region, to assess their current dietary and plasma levels of trans C18:1, the major trans-fatty acid (TFA), and cis-9, trans-11 CLA, and trans-10, cis-12 CLA, the two major conjugated linoleic acid (CLA) isomers, and to evaluate their correlation with several cardiovascular disease risk factors. The population was a random sample derived from the Catalan Nutrition Survey. Plasma levels of the CLA isomers were determined in a subsample of 100 volunteers. The Catalan diet seemed to maintain some traits of the ‘traditional’ Mediterranean diet, although other components were lost. The dietary intakes of saturated fatty acids (SFA), TFA, cis-9, trans-11 CLA, and trans-10, cis-12 CLA were 12.3%, 0.84% (2.0 g/d), 0.030% (71.5 mg/d), and 0.0015% (3.4 mg/d) of the energy intake, respectively. Trans C18:1 accounted for 0.19% of the total plasma fatty acids, while the sum of cis-9, trans-11and trans-10, cis-12 CLA isomers represented about 0.09% of the plasma fatty acids. Trans C18:1 isomers correlated significantly with the intake of French fries and pastries, while cis-9, trans-11 CLA significantly correlated with the intake of dairy products and ruminant meat. None of the cardiovascular disease risk factors were found to be associated with the plasma levels of TFA or CLA. The results of this study suggest that monounsaturated fatty acids (MUFA) are the main dietary fat source in the Catalan population, due to their regular olive oil consumption. Moreover, plasma levels of the main TFA and CLA suggest that the Catalan diet is not at present strongly influenced by the occidental dietary patterns. However, a reduction of the intake of SFA in the Catalan population should be recommended.

Comparative Study of High-Linoleic Acid Vegetable Oils for the Production of Conjugated Linoleic Acid

Conjugated linoleic acid (CLA) is found in small quantities in dairy and beef products. Obtaining optimum dietary CLA levels from these sources requires an increased intake of saturated fat. A 20% CLA soy oil was produced by UV photoisomerization of soy oil linoleic acid (LA), which is naturally low in saturated fat, but no other high-LA vegetable oils have been studied for their potential as CLA-rich oils. The objectives of this research were to (1) compare flax, sunflower, corn, soy, and high-LA safflower oils as sources of CLA-rich vegetable oils using laboratory-scale equipment, (2) compare CLA yields obtained by laboratory-scale and pilot-scale equipment, and (3) compare the oxidative stabilities of laboratory-scale processed oils. High-LA safflower oil produced the most CLA; soy oil produced slightly less, followed by corn, with flax producing very little and sunflower none at all. Minor oil components and turbidity reduced CLA yields, suggesting that oils should be highly refined before CLA production. The pilot-scale system was more effective than the laboratory-scale system due to greater light exposure and larger surface area to volume ratio of the oil samples. The oxidative stabilities of high-LA safflower oil and soy oil were similar before or after irradiation, indicating that these oils are the most suitable for high-CLA production.

A Conjugated Linoleic Acid-Enriched Beef Diet Attenuates Lipopolysaccharide-Induced Inflammation in Mice in Part through PPARγ-Mediated Suppression of Toll-Like Receptor 41–3

Conjugated linoleic acid (CLA) is a PUFA found in beef and dairy products that has immunoregulatory properties. The level of CLA in beef can be enhanced by feeding cattle fresh grass rather than concentrates. This study determined the effect of feeding a high-CLA beef diet on inflammation in an in vivo model of septic shock. Mice were fed a high-CLA beef (4.3% total fatty acid composition) or low-CLA beef diet (0.84% total fatty acid composition) for 6 wk. Lipopolysaccharide (LPS; 3 μg) or sterile PBS was injected i.v. and serum was harvested 6 h after injection. Serum interleukin (IL)-1β, IL-12p70, IL-12p40, and interferon-γ concentrations were significantly reduced in response to the LPS challenge in the high-CLA beef diet group. Bone marrow-derived dendritic cells (BMDC) from the high-CLA beef diet group had significantly less IL-12 and more IL-10 in response to ex vivo LPS stimulation. Furthermore, toll-like receptor 4 (TLR4) and CD14 protein and mRNA expression on BMDC was significantly attenuated in the high-CLA compared with the low-CLA beef diet group. Complimentary in vitro experiments to determine the specificity of the effect showed that synthetic cis9, trans11-CLA suppressed surface expression of CD14 and TLR4 on BMDC. Treatment with the PPARγ inhibitor GW9662 partially reversed TLR4 expression in immature BMDC. The results of this study demonstrate that feeding a diet enriched in high-beef CLA exerts profound antiinflammatory effects in vivo within the context of LPS-induced sepsis. In addition, downregulation of BMDC TLR4 is mediated through induction of PPARγ.

Trans-10,cis-12 Conjugated Linoleic Acid Induces Depolarization of Mitochondrial Membranes in HT-29 Human Colon Cancer Cells: A Possible Mechanism for Induction of Apoptosis

Conjugated linoleic acid (CLA), which is naturally present in a variety of foods such as milk fat and the meat of ruminant animals, has been demonstrated to exert chemoprotective effects in several tissues in experimental animals. CLA is a collective term, which denotes one or more positional and geometric isomers of octadecadienoic acid, with cis-9,trans-11 (c9t11) and trans-10,cis-12 CLA (t10c12) being the principal isomers in commercial preparations. We observed previously that physiological levels of CLA inhibited HT-29 cell growth, and the growth inhibitory effects of CLA were attributed to the effect of t10c12, but not c9t11. In the present study, we assessed the mechanisms by which physiological levels of CLA and t10c12 induce apoptosis in HT-29 cells. HT-29 cells were cultured for 3 days in serum-free medium in the presence of various concentrations of CLA (0-20 micromol/L) or t10c12 (0-4 micromol/L). Addition of CLA or t10c12 to culture medium resulted in a dose-dependent increase in the numbers of apoptotic cells. The results of western blot analysis of total cell lysates showed that CLA and t10c12 increased the levels of cleaved caspase-9, caspase-3, and poly(ADP-ribose) polymerase but did not alter the levels of Bcl-2 family member proteins. However, these fatty acids were shown to increase the translocation of Bad and Bax to the mitochondria, increase mitochondrial membrane permeability, and induce the release of cytochrome c and Smac/Diablo from the mitochondria. In addition, CLA and t10c12 diminished Akt content and Akt phosphorylation. These findings indicate that physiological levels of t10c12 induce apoptosis in HT-29 colon cancer cells, which is mediated via mitochondrion-mediated events associated with a decline in Akt activity, an increase in the translocation of the pro-apototic Bad and Bax to the mitochondria, and the subsequent disruption of normal mitochondrial membrane potential.

Maternal dietary conjugated linoleic acid is not directly toxic for the developing chick embryo, but causes embryo mortality by altering fatty acid composition of the egg yolk in the chicken

AbstractBACKGROUND: Conjugated linoleic acid (CLA) was shown to cause embryo mortality when added into chicken diets. The objective of this study was to determine if CLA accumulation in yolk was directly responsible for embryo mortality.MATERIAL AND METHODS: Forty‐two 30‐week‐old hens were assigned to seven groups and fed a diet containing 5 g kg−1 canola oil (Group A), 5 g kg−1 CLA (Group B), 5 g kg−1 CLA plus 20 g kg−1 canola oil (Group C), 5 g kg−1CLA plus 30 g kg−1 canola oil (Group D), 5 g kg−1 CLA plus 40 g kg−1 canola oil (Group E), 10 g kg−1 CLA plus 40 g kg−1 canola oil (Group F) or 20 g kg−1 CLA plus 40 g kg−1 canola oil (Group G) for 22 days. Collected eggs were held at 15 °C for 24 h, and then incubated. For fatty acid analysis, three eggs were collected on the 22nd day of the study.RESULTS: After the sixth day, embryonic mortality was 100% in eggs from Group B versus 2, 30, 21, 4, 0, and 9% in groups A, C, D, E, F and G, respectively. The ratio of SFA/UFA of yolks from groups A, B, C, D, E, F and G was 0.64, 1.53, 1.07, 1.06, 1.08, 1.05 and 1.13, respectively. Relative levels (%) of CLA in the eggs from the groups A, B, C, D, E, F and G were 0.12, 2.29, 1.68, 1.80, 1.76, 3.04, and 5.25%, respectively.CONCLUSION: This study showed that CLA was not directly toxic for developing embryo, but caused mortality in the fertile eggs by increasing the ratio of SFA to UFA in egg yolk. Copyright © 2009 Society of Chemical Industry

Characterization of Conjugated Linoleic Acid Production by Bifidobacterium breve LMC 520

This study was performed to characterize the CLA production ability of a bacterial strain, Bifidobacterium breve LMC 520, which can actively convert linoleic acid (LA) to cis-9,trans-11 conjugated linoleic acid (CLA), a major isomer derived from microbial enzymatic conversion. The culture conditions were optimized to improve CLA production under the aerobic conditions. B. breve LMC 520 was tested with different amounts of LA in varied culture conditions, such as air, additives, and pH. A maximal level of CLA production (up to 90% of substrate) was obtained after 24 h of incubation in culture medium containing 1 mM LA at pH 5.5 and under anaerobic conditions. There was no decline in the CLA level with prolonged incubation until 48 h. When the effect of pre-incubation with LA on CLA production was tested, there was no significant difference between the CLA-producing activity of pre-incubated and untreated bacteria at the third passage but there was a significant reduction in CLA production by the pre-incubated cells after the fourth passage. These results demonstrate that the CLA-producing activity of B. breve LMC 520 could be maximized by numerous environmental factors. The data also indicate its potential for increasing CLA accumulation in dairy products when B. breve LMC 520 is used as a functional starter culture.

Volatile compounds of experimental liver pâté from pigs fed conjugated linoleic acid in combination with monounsaturated fatty acids

AbstractBACKGROUND: Feeding conjugated linoleic acid (CLA) to pigs leads to CLA‐enriched meat products, which are of current interest owing to the potential health properties of CLA. However, dietary CLA increases the ratio of saturated to monounsaturated fatty acids (MUFA) in pig tissues. Combining CLA with high MUFA levels in pig diets may counteract this effect. Owing to the modification of fatty acid composition, variation in the volatile profile of derived meat products might be expected. The aim of the present work was to study the volatile profile, and its change during storage, of experimental liver pâté manufactured from pigs fed different levels of CLA and MUFA.RESULTS: Regardless of the CLA or MUFA level, 98 compounds were identified. Lower area units were observed for most branched aldehydes, ketones and alcohols and some furans, sulfur compounds and nitrogen compounds with increasing CLA and MUFA contents. Levels of nonanal, propan‐2‐one, dodecane, 2‐pentylfuran and ethylbenzene were higher in CLA pâtes. The effect of experimental diets on the change in volatiles during storage was not significant.CONCLUSION: Supplementation of pig diets with CLA isomers in combination with low or high MUFA levels seems to have a significant effect on the volatile profile of pork liver pâté. Copyright © 2009 Society of Chemical Industry

Effect of conjugated linoleic acid on dietary lipids utilization, liver morphology and selected immune parameters in sea bass juveniles (Dicentrarchus labrax)

Increased energy content in fish feeds has led to an enhanced fat deposition, particularly in European sea bass, concerning fish farmers. Inclusion of conjugated linoleic acid (CLA) could reduce fat deposition as in other vertebrates. To determine if dietary CLA affects fat deposition, lipid metabolism, lipid composition and morphology of different tissues, growth and selected immune parameters, European sea bass juveniles were fed 4 graded levels of CLA (0, 0.5, 1 and 2%). Growth and feed conversion were not affected by CLA, whereas feed intake was reduced (P<0.05) by feeding 2% CLA. In these fish perivisceral fat was also reduced (P<0.05), particularly reducing (P<0.05) monounsaturated fatty acids. CLA has not affected tissue proximal composition, but reduced (P<0.05) saturated and monounsaturated fatty acids and increased (P<0.05) the n-3 and n-3 highly unsaturated fatty acids in muscle and increase (P<0.05) CLA content in muscle, liver and perivisceral fat. A progressive reduction in lipid vacuolization of hepatocytes cytoplasm and regular-shaped morphology was found in fish fed increased CLA levels, together with a progressive increase in malic enzyme activity (only significant in fish fed 1% CLA). Finally, inclusion of CLA up to 1% increased (P<0.05) plasma lysozyme activity and was positively correlated with alternative complement pathway.

Effect of breed on fatty acid composition and stearoyl-CoA desaturase protein expression in the Semimembranosus muscle and subcutaneous adipose tissue of cattle

The present study investigated (i) the effect of breed on the expression of stearoyl-CoA desaturase (SCD) protein and fatty acid composition in Semimembranosus muscle and subcutaneous adipose tissue of beef cattle and (ii) the relationship between SCD expression, cis-9, trans-11 conjugated linoleic acid (CLA) content, and monounsaturated fatty acid (MUFA) level. The study was conducted on the following breeds: Longhorn (L), Charolais cross with Holstein–Friesian (CX), Hereford (H), Belted Galloway (BG) and Beef Shorthorn (BS). Significant breed differences in the total fatty acid content, saturated fatty acid (SFA) level, MUFA and n−3 PUFA content were observed in subcutaneous adipose tissue but not in muscle. In the case of CLA, the breed differences were observed in both muscle and subcutaneous adipose tissue, with the highest level in L and the lowest level in H. In the case of subcutaneous adipose tissue, the breed with the highest CLA content (L) also had the highest SCD protein expression. The breed-specific pattern of SCD expression in subcutaneous adipose tissue was similar to the breed-specific pattern of one of the products of an SCD-catalysed reaction, C16:1 (BS < BG < H < CX < L). It has been concluded that (i) the mechanisms regulating SCD protein expression and CLA level in beef cattle are tissue-specific; (ii) breed-specific variations in SCD expression might contribute to breed variations in MUFA and CLA content in subcutaneous adipose tissue but not in Semimembranosus muscle.

Egg yolk conjugated linoleic acid alters phospholipid molecular species in chick tissues

AbstractThe effects of egg conjugated linoleic acid (CLA) on chick yolk sac and liver phospholipid composition and molecular species were determined. Fertile eggs with no (control), low (CLA1) or high (CLA2) levels of CLA were incubated. Upon hatching, total lipid in the remnant yolk sac constituted 11.5, 18.9 and 15.3% in control, CLA1 and CLA2, respectively (p &lt;0.05). Maternal CLA led to a decrease in phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) and an increase in lysophosphatidylcholine (LPtdCho) in the yolk sac and liver tissues of CLA1 and CLA2 when compared to control (p &lt;0.05). The effect of maternal dietary CLA was very prominent in yolk sac PtdCho (34:1) where 13 and 38% reductions were observed in CLA1 and CLA2, respectively, when compared to control. Among different liver PtdCho species, the highest difference was found in 36:2, where a 41% increase was observed in CLA2 when compared with control chicks. The liver LPtdCho of CLA1 and CLA2 chicks had a 92% increase in 16:0 and 18:0 when compared to control. Over 80% increase was observed for 18:2 and 20:4 in the liver LPtdCho of CLA2 chicks compared to control. These results suggest that the yolk CLA content alters the proportions of phospholipids in the progeny during avian embryogenesis.

FATTY ACID COMPOSITION AND CONJUGATED LINOLEIC ACID CONTENT OF COW AND GOAT CHEESES FROM NORTHWEST ARGENTINA

ABSTRACT In this study, we evaluated chemical characteristics, fatty acid composition and conjugated linoleic acid (CLA) content of cow and goat cheeses from Northwest Argentina. Similar chemical and fatty acid composition were determined in milk and cheese of both species. Palmitic, oleic and myristic acids were the most abundant fatty acids in dairy products. CLA level averaged 0.85 and 0.96 in milk and 0.76 and 1.04 g/100 g of fatty acids in cheese of cow and goat, respectively. Cis‐9,trans‐11 was the major isomer present in both species. Significant differences in CLA desaturase activity were observed, showing a value of 0.068 and 0.064 in milk, and 0.077 and 0.071 in cheese of cow and goats, respectively. Good nutritional properties were determined for cheeses of both species, which are fed on natural pasture during spring and summer seasons. Goat's cheese represents a higher source of CLA for human consumers than cow's cheese, offering from 156.6 to 222.6 mg/ 100 g of sample.PRACTICAL APPLICATIONSThe present work shows the fatty acid composition and chemical characteristics of two fresh cheeses manufactured with cow and goat milk. Animals were fed on natural pasture during summer and spring seasons. It is known that pasture increases conjugated linoleic acid (CLA) concentration in milk fat, and the content in cheese is directly related to it. The CLA content of dairy products for the human consumers was analyzed, showing goat cheese with high polyunsaturated fatty acid content, including CLA. Cow and goat fresh cheese offer CLA as many ripening products of different countries, as cheddar or hard cheeses. Lipid composition of food is related to many illnesses, but some compounds are beneficial to human health. The main sources of CLA are milk and cheeses, and in Northwest of Argentina, no data are reported about it, where artisanal cheeses are consumed by the population. Therefore, the atherogenicity index was determined as well.

Conjugated linoleic acid (CLA) and fatty acid composition of milk, curd and Grana Padano cheese in conventional and organic farming systems

CLA levels and fatty acid composition were measured to compare the fat composition in organic bulk milk, destined to the production of Grana Padano cheese, with those produced by conventional system. The curds and Grana Padano cheeses were also analysed to evaluate the effects of the production technology on the CLA content. All analysed organic samples were characterized by higher annual means of CLA, vaccenic acid (TVA) and linolenic acid (LNA) in comparison with conventional samples (with P<0.05). Nevertheless, no particular effect of the production technology was seen on the CLA content. The animal diet appears to be the factor which has the highest effect on the CLA concentration in milk and milk products and an organic diet based on fresh or dried forage, that is rich in CLA precursory fatty acids, may improve the yield of fatty acids with beneficial effects on health.

Increasing omega fatty acid content in cow's milk through diet manipulation: Effect on milk flavor

Milk with an increased content of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and conjugated linoleic acid (CLA) was obtained by incorporating fish oil into the feed of cows. The 4 feed treatments used were a control diet of 57% forage and 43% concentrate mix with EnerGII fat supplement at 1.65% of dietary DM, or EnerGII in the basal diet was partially replaced with 1) 0.21% partially ruminally inert calcium salts of 71% fish oil given at 0.41% of DM; 2) 0.41% inert calcium salts of 71% fish oil given at 0.83% of DM; or 3) 0.83% inert calcium salts of 43% fish oil given at 0.83% of DM. The cows were milked after 5 and 8 wk and the EPA, DHA, and CLA contents in the pasteurized whole milk were determined. The presence of off-flavors in the milk was investigated after 3 and 10 d of storage. Twelve judges were trained to evaluate the presence of grassy, fishy, oily, oxidized, and rancid off-flavors. Although levels of EPA, DHA, vaccenic acid, and CLA increased for all 4 treatments, a trained sensory panel detected no difference in milk flavor between treatments and the control, with little or no intensity of off-flavors. Results suggest that feeding fish oil and EnerGII at varying levels enhanced CLA, EPA, DHA, and total n-3 fatty acids in milk over the length of the experiment without negatively affecting milk flavor. This creates the potential for a more marketable and healthful product.

Variations in Conjugated Linoleic Acid (CLA) Content of Processed Cheese by Lactation Time, Feeding Regimen, and Ripening

Dairy products are major sources of conjugated linoleic acid (CLA); thus, an increase in CLA content can improve the quality value of dairy products. The objective of this work was to determine the effects of lactation time, feeding regimen, and ripening period on the level of CLA in processed cheese. CLA content in milk varied with the period of lactation; high in spring (April and May, about 6.8 mg CLA/g fat) and relatively low in mid summer and winter (about 4.3 mg CLA/g fat). The effects of dietary regimen and ripening period were determined in milk, which was obtained from March to May. After aging for 4 months, the cheese made from milk obtained from cows fed on pasture contained relatively higher levels of CLA compared to cheese made from milk obtained from cows fed indoors (8.12 mg CLA/g fat vs 6.76 mg CLA/g fat), but there was no difference in 7 month-aged cheeses. In both pasture and indoor feeding, 7 month-aged cheeses showed higher CLA content than 4 month-aged cheeses. The contents of stearic acid (C18:0) and linolenic acid (C18:3) were significantly higher in cheese from pasture fed cows compared to those in cows fed indoors. These findings should be helpful for the efficient production of functional dairy products with high CLA contents.

Conjugated linoleic acid isomer concentrations in milk from high‐ and low‐input management dairy systems

AbstractBACKGROUND: Different conjugated linoleic acid (CLA) isomers are known to have contrasting physiology or health effects and there is growing evidence that the profile of natural isomers in milk is influenced by the production system. This survey is the first to compare feeding regimes and concentrations of 14 CLA isomers in milk from three production systems in the UK.RESULTS: Total CLA and seven isomers (including C18:2 c9t11 which comprised &gt; 80% of total) were significantly higher in milk from both organically certified and non‐certified low input (LI) systems compared with milk from conventional high input farms. Sampling date also affected concentrations of total CLA and nine isomers; being lowest in March and highest in August. Seasonal differences were greater in milk from LI herds, thought to be due to changes in herbage and/or stage of lactation. Multivariate analysis showed a strong positive relationship between several CLA isomers and increasing levels of fresh forage in the diet.CONCLUSIONS: These results add to the evidence on how management adjustment may improve the profile of CLA isomers in milk fat, although animal or human intervention studies are required to identify the effects of consuming milk with different CLA levels and isomer profiles on human health. Copyright © 2009 Society of Chemical Industry

Survey on conjugated linoleic acid (CLA) content and fatty acid composition of Grana Padano cheese produced in different seasons and areas

A study was carried out to determine the content of conjugated linoleic acid (CLA) and fatty acid composition of Grana Padano P.D.O. (Protected Designation of Origin) Italian cheese. Samples were obtained from spring and summer cow’s milk in different areas of Grana Padano production district and from all present dairies. In particular, 253 samples of lowland-hill Grana Padano (LH-GP) were analysed: 137 produced from spring milk, and 116 from summer milk. Forty-three mountain Grana Padano (M-GP) samples were also analysed: 25 obtained from spring milk, and 18 from summer milk. The results were subjected to statistical analysis; a factorial arrangement was used, and the fixed effects in the model included season, the manufacturing area of the Grana Padano cheese, and the first order interaction (season x area). Further, cheese β-carotene concentration was measured in a representative number of summer samples (32), selected according to the CLA level (9 with CLA concentration <5; 10 with CLA value ranging from 5 to 7; 13 with CLA level >7 mg/g total fat), in order to investigate the correlation between CLA content and β-carotene concentration.M-GP had higher levels of CLA, vaccenic (TVA) and α-linolenic (LNA) acid than LH-GP. CLA concentrations increased from spring to summer both in M-GP and LH-GP. This rise was greater in M-GP showing an effect of interaction between season and production area (P<0.001). An effect of first order interaction (P<0.001) was also seen for TVA with values increasing from spring to summer in M-GP, whereas there only was an effect of the manufacturing area on LNA. During summer, M-GP had the highest polyunsaturated fatty acids (PUFA) percentage. An increase in PUFA from spring to summer was observed only in M-GP (first order interaction, P<0.001). The saturated fatty acids (SFA) decreased from spring to summer both in LH-GP and M-GP and with major entity in M-GP (first order interaction, P<0.001). The β-carotene concentration resulted positively correlated with CLA level (r=0.92; P<0.01) in summer cheese.The present results underline the role of mountain cheese obtained from summer milk as a natural source of CLA and beneficial fatty acids for human health.

The effects of dietary conjugated linoleic acid (CLA) on fatty acid composition and key enzymes of fatty acid oxidation in liver and muscle of geese

The objective of this study was to determine the influence of conjugated linoleic acid (CLA) on fatty acid composition and key enzymes of fatty acid oxidation in liver and muscle of geese. A total of 192 1-day-old geese were randomly assigned to 1 of 4 dietary groups, and were fed for 56 days on diets containing 2.5% soybean oil (group A, control group) or 2.0% soybean oil with 0.5% CLA (group B), 1.0% soybean oil with 1.5% CLA (group C), and 2.5 % CLA (group D). Geese fed CLA had a decreased abdominal fat percentage (AFP) (P < 0.01) compared with the control. It was observed that dietary CLA levels had a significant effect on the body weight, weight gain, feed conversion rate (FCR) (P < 0.05), and feed intake (P < 0.01). Fatty acid composition showed a significant increase of the biologically active cis-9, trans-11 and trans-10, and cis-12 CLA isomers in both liver and muscle of geese fed CLA (P < 0.01). Dietary CLA led to an increase (P < 0.01) in saturated fatty acid (SFA) and a reduction in monounsaturated fatty acid (MUFA) (P < 0.05) concentrations in both liver and muscle. In liver, dietary CLA increased (P < 0.05) acyl CoA oxidase (ACO) activity, but did not affect carnitine palmitoyltransferase-I (CPT-I) activity compared with the control. CPT-I activity was significantly increased by 2.5% dietary CLA in muscle, where ACO activity was decreased at 1.5% CLA level. The results obtained suggested that geese can successfully incorporate CLA in both liver and muscle, which could be beneficial in the human diet, through provision of bioactive fatty acids with no detrimental effects on n-3 PUFA levels.

Manipulation of the fatty acids composition of poultry meat and giblets by dietary inclusion of two oil sources and conjugated linoleic acid

The effect of dietary conjugated linoleic acid (CLA) in association with two vegetable oil sources on the fatty acids of meat and giblets of broiler chickens was evaluated. Two hundred 21-day-old broiler chickens were distributed in a completely randomized factorial design 2 x 5 (two oil sources, soybean or canola oil; and five levels of CLA, 0.0, 2.5, 5.0, 7.5, and 10.0g/kg). The addition of CLA to the diet resulted in an increase (P&lt;0.05) in CLA deposition in the analyzed tissues. CLA supplementation also reduced (P&lt;0.05) the rate of polyunsaturated to saturated fatty acids in thigh, breast, heart, and gizzard. There was interaction of CLA x oil source (P&lt;0.05). The intake of soybean oil, associated with increasing CLA, resulted in an increase in lipid deposition in edible portions as observed by an increase in the overall content of fatty acids, including CLA, while the use of canola oil, associated with increasing CLA in the diet, resulted in a decrease in lipid content in edible portions, specifically regarding that of saturated fat (P&lt;0.05) in breast meat and liver and in the content of monounsaturated fatty acids (P&lt;0.05) in thigh, breast, liver, and gizzard.

Content of conjugated linoleic acid in neutral and polar lipid fractions of milk of different ruminant species

The aim of this research was to investigate the distribution of conjugated linoleic acid (CLA) in the neutral and polar milk lipid fractions of samples of bovine, ovine and caprine milk. Lipids were fractionated by thin-layer chromatography to obtain triglyceride, diglyceride and monoglyceride fractions. Phospholipids were separated by solid-phase extraction. The CLA content was quantitatively determined after transmethylation and addition of internal standard. As expected, 95–97% of the CLA was found in the triglyceride fraction. The main differences between the species were observed in CLA content of the diglyceride and phospholipid fraction, while the amount of CLA in the monoglycerides fraction was negligible. Cows' milk showed comparable contents of CLA in both diglyceride and phospholipid fractions (4.2 and 5.5 mg 100 g −1 of lipids, respectively). The level of CLA in phospholipids of ewes' (38 mg) and goats' (20 mg) milk lipids was four times higher than the level of CLA in diglycerides (7 and 5 mg, respectively). In terms of the phospholipid content, CLA accounted for 2–4% (calculated as a percentage of total fatty acids esterified in phospholipids) in caprine and ovine and less than 1% in bovine milk.