Variation in fat content and fatty‐acid composition of the Baltic herring Clupea harengus membras

The fat content and fatty‐acid profiles of herring, Clupea harengus membras, from the southern Baltic Sea varied depending on when (fishing season) and where (fishing grounds) the fish were caught as well as on their size and sex. The fat, protein and dry matter content and the fatty‐acid profiles were assayed in C. h. membras muscle tissue. The changes observed in fatty‐acid profiles were determined by factors such as specimen mass and fat content, which, in turn, depended on fishing season. This is explained by dietary differences between juvenile and older fish. Gonad maturation and spawning in the latter are also factors. The study results provide confirmation of the hypothesis that polyunsaturated fatty acids (PUFA), in particular docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), play vital roles in the sexual maturation of C. h. membras.     

Lipoprotein lipase activity and its relationship to high milk fat transfer during lactation in grey seals

Lipoprotein lipase regulates the hydrolysis of circulating triglyceride and the uptake of fatty acids by most tissues, including the mammary gland and adipose tissue. Thus, lipoprotein lipase is critical for the uptake and secretion of the long-chain fatty acids in milk and for the assimilation of a high-fat milk diet by suckling young. In the lactating female, lipoprotein lipase appears to be regulated such that levels in adipose tissue are almost completely depressed while those in the mammary gland are high. Thus, circulating fatty acids are directed to the mammary gland for milk fat production. Phocid seals serve as excellent models in the study of lipoprotein lipase and fat transfer during lactation because mothers may fast completely while secreting large quantities of high fat milks and pups deposit large amounts of fat as blubber. We measured pup body composition and milk fat intake by isotope (deuterium oxide) dilution and plasma post-heparin lipoprotein lipase activity in six grey seal (Halichoerus grypus) mother-pup pairs at birth and again late in the 16-day laction period. Maternal post-heparin lipoprotein lipase activity increased by an average of four-fold by late lactation (P=0.027), which paralleled an increase in milk fat concentration (from 38 to 56%; P=0.043). Increasing lipoprotein lipase activity was correlated with increasing milk fat output (1.3–2.1 kg fat per day) over lactation (P=0.019). Maternal plasma triglyceride (during fasting) was inversely correlated to lipoprotein lipase activity (P=0.027) and may be associated with the direct incorporation of longchain fatty acids from blubber into milk. In pups, post-heparin lipoprotein lipase activity was already high at birth and increased as total body fat content (P=0.028) and the ratio of body fat: protein incrased (P=0.036) during lactation. Although pup plasma triglyceride increased with increasing daily milk fat intake (P=0.023), pups effectively cleared lipid from the circulation and deposited 70% of milk fat consumed throughout lactation. Lipoprotein lipase may play an important role in the mechanisms involved with the extraordinary rates of fat transfer in phocid seals.Abbreviations FFA free fatty acid - HL hepatic lipase - LPL lipoprotein lipase - PH-HL post-heparin hepatic lipase - PH-LPL post-heparin lipoprotein lipase - VLDL very low density lipoprotein     

Comparative study on the fatty acid composition of two marine vertebrates: striped dolphins and loggerhead turtles

The fatty acid composition of total lipids extracted from seven different tissues (fat, liver, cerebrum, cerebellum, lung, kidney and muscle) of 10 striped dolphins (Stenella coeruleoalba) (weight 75.7±16.2 kg) found dead or moribund during a morbillivirus epizootic, and from two tissues (fat and liver) of 54 loggerhead turtles (Caretta caretta) (18.5±10.5 kg) seized dead after illegal capture, both from the Mediterranean Sea, have been determined by high resolution chromatography techniques. When comparing both species, fatty acid composition is surprisingly similar, with a predominance of the monoenoic followed by the saturated group of fatty acids, and a very close ratio of polyunsaturates n-3/n-6. The relatively high arachidonic acid content in the liver of the two marine species is remarkable. The similar diet can play an important role in these findings, but it is suggested that probably metabolic pathways and essential fatty acid requirements between both marine vertebrates are similar, more than is expected from their earlier filogenetic evolutionary divergence.     

Muscle fat composition of pheasants (<Emphasis Type="Italic">Phasianus colchicus)</Emphasis>, wild ducks (<Emphasis Type="Italic">Anas platyrhynchos</Emphasis>) and black coots (<Emphasis Type="Italic">Fulica atra</Emphasis>)

The aim of this investigation was to characterise the fatty acid composition within intramuscular fat (IMF) of two muscles (breast and thigh) from 28 pheasants, ten wild ducks and 27 black coots from Slovakia. A high variability for all single fatty acids (FA) and the total fat concentration in muscles of wild birds was identified. Black coots deposited the highest fat in breast muscle whereas wild ducks and pheasants accumulated more lipids in thigh muscle. In general, the content of polyunsaturated fatty acids (PUFA) of the IMF in wild bird muscles was high, and the saturated FA concentration was lower compared with muscles of domestic farm animals. The ratio between PUFA and saturated fatty acids (PSQ) ranked between 0.6 and 1.2, and the ratio of n-6/n-3 fatty acid was favourably low in black coot and wild pheasants (3.2 and 2.9, respectively). Farmed pheasants had increased IMF and more saturated and n-6 fatty acids deposited in thigh muscle but not in breast muscle.     

Joint analysis of additive,dominant and first‐order epistatic effects of four genes (IGF2, MC4R,PRKAG3 and LEPR) with known effects on fat content and fat distribution in pigs

LEPR, MC4R, IGF2 and PRKAG3 are genes with known effects on fat content and distribution in pig carcass and pork. In a study performed with Duroc × Landrace/Large White pigs, we have found that IGF2 has strong additive effects on several carcass conformational traits and on fatty acid composition in several anatomical locations. MC4R shows additive effects on saturated fatty acid content in several muscles. On the other side, almost no additive effect has been found for PRKAG3 and very few for LEPR. In this work, no dominant effect has been found for any of the four genes. Using a Bayesian Lasso approach, we have been able now to find first‐order epistatic (mainly dominant–additive) effects between LEPR and PRKAG3 for intramuscular fat content and for saturated fatty acid content in L. dorsii, B. femoralis, Ps. major and whole ham. The presence of interactions between genes in the shaping of traits of such importance as intramuscular fat content and composition highlights the complexity of heritable traits and the difficulty of gene‐assisted selection for such traits.     

Egg quality and female condition in vendace (Coregonus albula L.) before and during spawning

The fat content of muscle, liver and eggs of vendace (Coregonus albula L.) were measured during the maturation of ovaries in summer. The fat content of eggs was at its highest in July and that of muscle in August during the optimal feeding season. Significant differences were not found in fat content between lakes Suvasvesi and Southern-Kallavesi in central Finland. There were no essential differences in fatty acid composition between muscle, liver and eggs of Lake Suvasvesi vendace. During the last month before spawning in October the gross energy and fat contents of eggs decreased in Lake Suvasvesi vendace. The fat and vitamin C contents of muscle as well as the liver index of females decreased during this time also. In males the corresponding decrease did not occur, indicating that spawning is a greater stress for females than for males. The egg quality and condition of Lake Inarijärvi vendace were about the same as those of Lake Suvasvesi vendace. The unfavourable conditions of Lake Inarijärvi, located in northern Finland, are reflected in the size of ovaries, which is known to be smaller (gonadosomatic index < 20%) than in Lake Suvasvesi (GSI 26–27%). Vendace, then, maintain the quality of eggs at the expense of their number.     

Pancreatic ectopic fat is characterized by adipocyte infiltration and altered lipid composition

Objective: Sustained exposure to lipids is deleterious for pancreatic islet function. This could be mediated through increased pancreatic fat following increased dietary fat and in obesity, which has implications for the onset of type 2 diabetes. The aims of this study were to determine changes in extent and composition of pancreatic, hepatic, and visceral fat in mice fed a high‐fat diet (HFD, 40% by weight) compared with a control diet (5% fat) of similar fatty acid composition, and to compare composition and extent of pancreatic fat in human type 2 diabetes. Methods and Procedures: Mice were fed HFD for 3 or 15 weeks. Human postmortem pancreas was examined from subjects with type 2 diabetes (n = 9) and controls (n = 7). Tissue lipid content and composition were determined by gas chromatography and pancreatic adipocyte infiltration quantified by morphometry. Results: Pancreatic triacylglycerol (TG) content was 20× greater (P < 0.05) in HFD mice and there were more pancreatic perilipin‐positive adipocytes compared with controls after 15 weeks. The proportions of 18:1n ?9 and 18:2n ?6 in pancreatic TG and the 20:4n ?6/18:2n ?6 ratio in phospholipids, were higher (both P < 0.05) after HFD compared with controls. Human pancreatic TG content was correlated with the proportion of pancreatic perilipin‐positive adipocytes (r = 0.64, P < 0.05) and associated with unsaturated fatty acid enrichment (P < 0.05). Discussion: Adipocyte infiltration in pancreatic exocrine tissue is associated with high‐fat feeding in mice and pancreatic TG content in humans. This alters the fatty acid milieu of the islet which could contribute to islet dysfunction.     

Comparison of Fat–Water MRI and Single‐voxel MRS in the Assessment of Hepatic and Pancreatic Fat Fractions in Humans

The ability to accurately and noninvasively quantify fatty infiltration in organs such as the liver and the pancreas remains a critical component in understanding the link between obesity and its comorbidities such as type 2 diabetes and fatty liver disease. Single‐voxel (¹H) proton magnetic resonance spectroscopy (MRS) has long been regarded as the gold‐standard noninvasive technique for such measurements. Recent advances in three‐dimensional fat–water magnetic resonance imaging (MRI) methods have led to the development of rapid, robust, and quantitative approaches that can accurately characterize the proportion of fat and water content in underlying tissues across the full imaging volume, and hence entire organs of interest. One such technique is called IDEAL (Iterative Decomposition with Echo Asymmetry and Least squares estimation). This article prospectively compares three‐dimensional (3D) IDEAL‐MRI and single‐voxel MRS in the assessment of hepatic (HFF) and pancreatic fat fraction (PFF) in 16 healthy subjects. MRS acquisitions took 3–4 min to complete whereas IDEAL acquisitions were completed in 20‐s breath‐holds. In the liver, there was a strong correlation (slope = 0.90, r² = 0.95, P < 0.001) between IDEAL and MRS‐based fat fractions. In the pancreas, a poorer agreement between IDEAL and MRS was observed (slope = 0.32, r² = 0.51, P < 0.02). The discrepancy of PFF is likely explained by MRS signal contamination from surrounding visceral fat, presumably during respiratory motion. We conclude that IDEAL is equally accurate in characterizing hepatic fat content as MRS, and is potentially better suited for fat quantification in smaller organs such as the pancreas.     

Effect of Fat Sources on Satiety

Objective: There are inconsistent reports on the satiety value of different fatty acids. This study compared the appetitive effects of two fat sources rich in monounsaturated fatty acids (peanut oil and canola oil) with a source rich in saturated fatty acids (butter). Research Methods and Procedures: After an overnight fast, lean participants completed a questionnaire eliciting information about hunger, fullness, desire to eat, and prospective consumption. They then consumed one of the preloads (muffins containing 40 g of each fat source or no fat) and 150 mL of water within 15 minutes. Questionnaires were completed again 30, 60, and 120 minutes after preload ingestion. Participants kept dietary records during the subsequent 24 hours. Results: Canola and peanut oil muffins resulted in higher fullness, and butter, canola, and peanut oil muffins resulted in lower hunger ratings 30, 60, and 120 minutes after preload ingestion compared with the fat‐free preload. No differences were observed among the fat‐containing loads. Although energy intake 24 hours after consumption of the preloads was also comparable on days the three fat‐containing loads were consumed, energy consumption after each study session was higher when the fat‐free muffins were provided. However, total energy intake, including the calories provided by the preloads, was similar across treatments. Discussion: These data do not support a differential satiety effect of fat sources rich in monounsaturated fatty acids relative to one rich in saturated fatty acids.     

Influence of roughage/concentrate ratio and linseed oil on the concentration of trans-fatty acids and conjugated linoleic acid in duodenal chyme and milk fat of late lactating cows

Abstract

The objective of the study was to investigate the influence of two roughage-to-concentrate ratios, with or without linseed oil supplementation, on the flow of fatty acids in the intestinal chyme and the secretion in milk fat in late lactating cows. Seven late lactating cows fitted with cannulae in the dorsal rumen and simple T-shaped cannulae in the proximal duodenum were randomly assigned to four experimental periods applying an incomplete replicated 2×2 Latin square design. The rations consisted of meadow hay and a concentrate mixture given in a ratio of 70 : 30 or 30 : 70 on dry matter basis. The basal rations were fed without or with 200 g linseed oil daily. After three weeks of adaptation, samples from the duodenal chyme were taken to study the flow of fatty acids. Additionally, milk samples were analysed for their milk fat composition. Decreasing roughage/concentrate ratio and linseed oil supplementation significantly increased the flow of monounsaturated fatty acids (MUFA), trans-fatty acids (tFA) and conjugated linoleic acids (CLA) in the duodenum. Furthermore, linseed oil increased the flow of saturated fatty acids (SFA) in the duodenum. Higher concentrate portion (H 30) and linseed oil supplementation significantly decreased the milk fat content. SFA were lower (p < 0.05) and MUFA were higher (p < 0.05) in milk fat after linseed oil supplementation; H 30 resulted in more polyunsaturated fatty acids (PUFA, p < 0.05) in the milk. Linseed oil supplementation significantly increased tFA and CLA in milk fat. The higher CLA content in milk fat as compared to that in the digesta suggests that a substantial endogenous synthesis of CLA in the mammary gland tissue through Δ9-desaturase took place. Between 21% and 48% of duodenal t11-C_18:1 were converted into c9, t11-CLA in milk fat.     

Protein utilization during starvation in fat and lean Svalbard ptarmigan (Lagopus mutus hyperboreus)

Summary Body protein sparing during starvation has been examined in fat and lean Svalbard ptarmigan. Protein utilization was determined from daily N excretion and from the rate of decrease in body mass. Changes in plasma concentrations of -hydroxybutyrate, free fatty acids, glucose, and uric acid were also recorded. When fat birds were starved for 15 days protein catabolism initially fell (phase I) and was thereafter kept low (phase II). This was evident from the temporal pattern in both N excretion and body mass loss. In two birds, N excretion eventually increased, revealing enhanced protein catabolism and thus a third phase of starvation. Changes in protein utilization were paralleled by changes in plasma uric acid. Approximately 9% of the energy demand was covered by breakdown of body protein during phase II. The importance of fat catabolism in providing energy was indicated by markedly elevated plasma levels of -hydroxybutyrate and free fatty acids. When lean birds were starved for 5 days there appeared to be no phase II. The temporal pattern of body mass loss indicated phase I and III but that of N excretion only phase III. The relative contribution of body protein to energy demand increased from 22% at day 2 to 41% at the end of starvation and was paralleled by increased plasma uric acid. When data from lean and fat birds were pooled, the changes in uric acid and N excretion were highly correlated (r=0.92, P<0.001), indicating that plasma uric acid is a reliable index of protein breakdown in starving Svalbard ptarmigan. In conclusion, starving fat Svalbard ptarmigan have a much greater capacity to spare body protein than lean birds. Fat birds effectively reduce protein catabolism and maintain this at a low level whereas starving lean birds increase protein catabolism.Abbreviations -OHB -hydroxybutyrate - BM body mass - BMR basal metabolic rate; dne daily nitrogen excretion - FFA free fatty acids - MR metabolic rate     

Alterations in fatty acid kinetics in obese adolescents with increased intrahepatic triglyceride content

Objective: It has been hypothesized that excessive fatty acid availability contributes to steatosis and the metabolic abnormalities associated with nonalcoholic fatty liver disease (NAFLD). The purpose of this study was to evaluate whether adipose tissue lipolytic activity and the rate of fatty acid release into plasma are increased in obese adolescents with NAFLD. Methods: Palmitate kinetics were determined in obese adolescents with normal (n = 9; BMI = 37 ± 2 kg/m²; intrahepatic triglyceride (IHTG) ≤5.5% of liver volume) and increased (n = 9; BMI = 36 ± 2 kg/m²; IHTG ≥ 10% of liver volume) IHTG content during the basal state (postabsorptive condition) and during physiological hyperinsulinemia (postprandial condition). Both groups were matched on body weight, BMI, percent body fat, age, sex, and Tanner stage. The hyperinsulinemic‐euglycemic clamp procedure, in conjunction with a deuterated palmitate tracer infusion, was used to determine free‐fatty acid (FFA) kinetics, and magnetic resonance spectroscopy was used to determine IHTG content. Results: The rate of whole‐body palmitate release into plasma was greater in subjects with NAFLD than those with normal IHTG content during basal conditions, (87 ± 7 vs. 127 ± 13 µmol/min; P < 0.01) and during physiological hyperinsulinemia, (24 ± 2 vs. 44 ± 8 µmol/min; P < 0.01). Discussion: These results demonstrate that adipose tissue lipolytic activity is increased in obese adolescents with NAFLD and results in an increase in the rate of fatty acid release into plasma throughout the day. This continual excess in fatty acid flux supports the hypothesis that adipose insulin resistance is involved in the pathogenesis of steatosis and contributes to the metabolic complications associated with NAFLD.     

Food reserves of Scots pine (Pinus sylvestris L.)

Summary The amounts of starch, soluble sugars, triacylglycerols, diacylglycerols and free fatty acids were studied in Scots pine (Pinus sylvestris L.) during an annual cycle in current-year needles and in 1-, 2- and 3-year-old needles collected shortly after bud break. Determination of the compounds was performed using specific enzymatic assays, capillary gas chromatography and thin layer chromatography. Newly emerging needles contained relatively large amounts of starch, but only trace amounts of fat. During autumn and winter, fat content rose, while starch content decreased; amounts of both these reserve materials were very high the next spring shortly before bud break and decreased again during shoot elongation. Concentration of intermediates in triacylglycerol biosynthesis (diacylglycerols and free fatty acids), were low in summer and high in winter. The same pattern was observed for fructose and glucose (the predominant soluble sugars), galactose/arabinose and raffinose/melibiose. In contrast, sucrose concentrations were highest in spring and in autumn. Mature needles of different ages collected in May showed significant differences only in their triacylglycerol and starch content. Concentration changes of reserve materials are discussed in relation to season, mobilization and translocation processes, dormancy, frost resistance and the possibility of carbohydrate-fat interconversions.     

Influence of feeding whole sunflower seed and extruded linseed on production of dairy cows,rumen and plasma constituents,and fatty acid composition of milk

Holstein cows were fed total mixed rations (TMR) supplemented with protected palm fat (PPF), whole sunflower seed (WSS) or extruded linseed (ELS) for 100 days. Percentage of dietary crude fat was 5.3, 5.1 and 5.1, respectively. Diet had no (p > 0.05) effect on feed intake, milk yield or milk protein content. Percentage of milk fat and yield of fat – corrected milk were significantly increased when diets were supplemented with WSS and ELS. Feeding PPF resulted in the lowest (p < 0.05) ruminal concentration of volatile fatty acids. No significant dietary effect on plasma characteristics was observed. Concentration of polyunsaturated fatty acids (PUFA) was higher (p < 0.05), and PUFA n-6/n-3 ratio lower (p < 0.05), in the milk fat from cows fed ELS compared to WSS. Supplementation of TMR with oilseeds compared to PPF increased the content of CLA in milk fat (p < 0.005) and decreased its atherogenicity, primarily due to a significant reduction of palmitic acid concentration. Both oilseeds significantly improved the spreadability index of manufactured butter. ELS, but not WSS, increased the susceptibility of milk fat to oxidation (p < 0.05). It can be concluded that feeding of oilseeds to dairy cows improved nutritional quality of milk fat, with supplementation with ELS producing an even more desirable milk fatty acid profile than WSS supplementation.     

Formation and degradation of lipid bodies found in the riboflavin-producing fungus Ashbya gossypii

Microdroplets in the hyphae of Ashbya gossypii were found to become stained by Nile red. Purification of the stainable substance showed that the yellow fluorescent bodies consisted of triacylglycerol. During growth on glucose as the carbon source 8%–12% of the mycelial dry weight was found to be neutral lipid. When glucose declined in the medium, the content decreased to 3%–4% and the respiration quotient shifted to 0.6 indicating a reserve function of the fat. The fatty acid composition of the storage lipid was found to be strongly influenced by the carbon source. Mycelia cultivated on glucose contained 5% linoleic acid and 20% palmitoleic acid in their neutral fat while linoleic acid made up 54% and palmitoleic acid was not detectable (< 0.1%) in soybean-oil-grown mycelia. When plant oil was given as the sole carbon source, the fatty acid composition of the storage lipid showed a high similarity to the fed fat. ¹⁴C-labelled free oleic acid added to a culture growing on soybean oil was immediately incorporated into the fungal lipid. A pulse of 0.9 g/l free palmitoleic acid, fed during growth on olive oil, increased the content of this particular fatty acid in the fungal triacylglycerol from 0.8% to 9.6%. In addition, a liberation of free fatty acid and diacylglyceride was found in the culture supernatant when pure triolein was given as the sole carbon source. Obviously, the fungus cleaved the lipid serving as the carbon source extracellularly and used the liberated fatty acids for its storage lipid formation.This paper is dedicated to Prof. Dr. F. Wagner on the occasion of his 65th birthday     

Transgenic expression of n‐3 fatty acid desaturase (fat‐1) in C57/BL6 mice: Effects on glucose homeostasis and body weight

The fat‐1 gene, derived from Caenorhabditis elegans, encodes for a fatty acid n‐3 desaturase. In order to study the potential metabolic benefits of n‐3 fatty acids, independent of dietary fatty acids, we developed seven lines of fat‐1 transgenic mice (C57/BL6) controlled by the regulatory sequences of the adipocyte protein‐2 (aP2) gene for adipocyte‐specific expression (AP‐lines). We were unable to obtain homozygous fat‐1 transgenic offspring from the two highest expressing lines, suggesting that excessive expression of this enzyme may be lethal during gestation. Serum fatty acid analysis of fat‐1 transgenic mice (AP‐3) fed a high n‐6 unsaturated fat (HUSF) diet had an n‐6/n‐3 fatty acid ratio reduced by 23% (P < 0.025) and the n‐3 fatty acid eicosapentaenoic acid (EPA) concentration increased by 61% (P < 0.020). Docosahexaenoic acid (DHA) was increased by 19% (P < 0.015) in white adipose tissue. Male AP‐3‐fat‐1 line of mice had improved glucose tolerance and reduced body weight with no change in insulin sensitivity when challenged with a high‐carbohydrate (HC) diet. In contrast, the female AP‐3 mice had reduced glucose tolerance and no change in insulin sensitivity or body weight. These findings indicate that male transgenic fat‐1 mice have improved glucose tolerance likely due to increased insulin secretion while female fat‐1 mice have reduced glucose tolerance compared to wild‐type mice. Finally the inability of fat‐1 transgenic mice to generate homozygous offspring suggests that prolonged exposure to increased concentrations of n‐3 fatty acids may be detrimental to reproduction. J. Cell. Biochem. 107: 809–817, 2009. © 2009 Wiley‐Liss, Inc.     

Effects of fat source and dietary sodium bicarbonate plus straw on the conjugated linoleic acid content of milk of dairy cows

Abstract

The effects of fat source (0.7 kg of fatty acids from extruded soybeans or palmitic acid), of sodium bicarbonate (0.3 kg) plus straw (1 kg) and the interaction of these treatments on the content of conjugated linoleic acid (CLA) in the milk of dairy cows were examined. During nine weeks a group of 10 cows received a ration with palmitic acid and bicarbonate plus straw (ration PAB). During three periods of three weeks a second group of 10 cows received successively a ration with extruded soybeans and bicarbonate plus straw (ration ESB), a ration with palmitic acid without bicarbonate or straw (ration PA), and a ration with extruded soybeans without bicarbonate or straw (ration ES). Rations ES and ESB increased the content of polyunsaturated fatty acids in milk, but decreased milk fat content, compared to rations PAB and PA. Ration ESB led to the greatest milk CLA content, by a synergy between the high amount of dietary fat, and the action of bicarbonate plus straw, favouring trans11 isomers of CLA and C18:1, presumably via a ruminal pH near neutrality. Ration ES favoured trans10 isomers, not desaturated in the mammary gland, so that the milk CLA content was lower than with ration ESB, and resulted in the lowest milk fat content. In conclusion, a ration supplemented with both extruded soybeans and bicarbonate plus straw, was an efficient way to increase the CLA content in the milk of dairy cows.     

Effects of boiling,deep‐frying,and microwave treatment on the proximate composition of rainbow trout fillets: changes in fatty acids,total protein,and minerals

This study was conducted to investigate the differences in the proximate composition (moisture, fat, protein and ash), cholesterol content, energy, mineral composition (Na, Ca, Mg, K, P, Fe and Zn) and fatty acid profile of rainbow trout, Oncorhynchus mykiss, after frying, boiling, or microwaving. Results showed that all cooking methods reduced moisture and increased total protein, fat and ash contents. Also all minerals increased significantly during the microwave and frying methods. Statistical results showed that the major fatty acids among the saturated and monounsaturated fatty acids in each fish were palmitic (C16:0) and oleic (C18:1) acids, respectively. In addition, linoleic acid (C18:2) was predominant in the n‐6 polyunsaturated fatty acids (PUFA) in both cooked and raw trout. The EPA (eicosapentaenoic acid; C20:5 ω3) and DHA (docosahexaenoic acid; C22:6 ω6) acids were the major fatty acids among total n‐3 acids in fish samples. The fatty acids profile of the cooked fish showed a saturated (SFA) and monounsaturated (MUFA) decrease and an increase in PUFA contents. However, the ω‐3 fatty acids content increased in microwaved samples but decreased in the fried samples. Moreover, the PUFA/SFA and Hypocholesterolaemic/Hypercholesterolaemic (HH) ratios increased in both fried and microwaved trout, whereas significant increases in ω3/ω6 as well as EPA + DHA/C16 content were observed only in microwaved samples. A significant increase in energy content was observed in all cooked samples, whereas the cholesterol decreased. Research results show that microwaving is recommended as the best cooking method for a healthy consumption of rainbow trout.     

Metabolic Implications of Dietary Trans‐fatty Acids

Dietary trans‐fatty acids are associated with increased risk of cardiovascular disease and have been implicated in the incidence of obesity and type 2 diabetes mellitus (T2DM). It is established that high‐fat saturated diets, relative to low‐fat diets, induce adiposity and whole‐body insulin resistance. Here, we test the hypothesis that markers of an obese, prediabetic state (fatty liver, visceral fat accumulation, insulin resistance) are also worsened with provision of a low‐fat diet containing elaidic acid (18:1t), the predominant trans‐fatty acid isomer found in the human food supply. Male 8‐week‐old Sprague–Dawley rats were fed a 10% trans‐fatty acid enriched (LF‐trans) diet for 8 weeks. At baseline, 3 and 6 weeks, in vivo magnetic resonance spectroscopy (¹H‐MR) assessed intramyocellular lipid (IMCL) and intrahepatic lipid (IHL) content. Euglycemic–hyperinsulinemic clamps (week 8) determined whole‐body and tissue‐specific insulin sensitivity followed by high‐resolution ex vivo ¹H‐NMR to assess tissue biochemistry. Rats fed the LF‐trans diet were in positive energy balance, largely explained by increased energy intake, and showed significantly increased visceral fat and liver lipid accumulation relative to the low‐fat control diet. Net glycogen synthesis was also increased in the LF‐trans group. A reduction in glucose disposal, independent of IMCL accumulation was observed in rats fed the LF‐trans diet, whereas in rats fed a 45% saturated fat (HF‐sat) diet, impaired glucose disposal corresponded to increased IMCL_TA. Neither diet induced an increase in IMCL_soleus. These findings imply that trans‐fatty acids may alter nutrient handling in liver, adipose tissue, and skeletal muscle and that the mechanism by which trans‐fatty acids induce insulin resistance differs from diets enriched with saturated fats.     

Changes in fatty acid composition,cholesterol and fat‐soluble vitamins during development of eggs and larvae in shabbout (Barbus grypus,Heckel 1843)

Changes in fatty acid composition, cholesterol and fat‐soluble vitamins were studied during development (fertilized eggs, yolk‐sac larvae, and after yolk resorption of shabbout, Barbus grypus). Significant differences were found in the monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFA), PUFA/saturated fatty acids (SFA), ∑n‐3 and eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) ratios between eggs and larvae (P < 0.05). Significant differences were also observed in the C14:0, C16:1n‐7, C18:1n‐9, C18:3n‐6, C20:0, C20:4n‐6, C24:0, C24:1, C22:6n‐3 fatty acids between eggs and larvae after yolk‐sac resorption (P < 0.05). Vitamin α‐ Tocopherol and retinol content increased during embryogenesis, but changes were insignificant in retinol acetate, δ‐Tocopherol, K1, K2 and cholesterol content between eggs and larvae after yolk resorption (P > 0.05).