Fatty acid profile of muscles,liver and mesenteric fat in wild and reared perch (Perca fluviatilis L.)

This study addressed determinations of the fatty acid profile of muscle, liver and mesenteric fat in European perch originating from natural aquifers and from intensive rearing in a closed circuit on an artificial feed mixture. The qualitative composition of fatty acids was identical in both groups of perch, except for 16:4 acid identified exclusively in the reared perch. The study demonstrated equal concentrations of saturated (SFA) and unsaturated (UFA) fatty acids in muscles, liver and mesenteric fat of both groups of perch. The wild fish, however, were characterised by lower concentrations of monoenoic (MUFA) and higher concentrations of polyenoic (PUFA) fatty acids. Analyses also demonstrated similar contents of n − 3 PUFA in muscles and their diversified concentrations in liver and mesenteric fat (higher in the wild fish), as well as a higher content of n − 6 PUFA in all samples. The lower content of MUFA in the wild perch was mainly due to lower concentrations of cis18:1 n − 9 and 20:1 n − 9, whereas the higher content of n − 3 PUFA was due to a higher concentration of DHA, and the higher content of n − 6 PUFA was due to a higher concentration of arachidonic acid (AA). The biggest differences between wild and reared perch were detected for AA. The wild and reared perch were also found to differ in the n − 3/n − 6 ratio (higher in the reared fish) and to have similar values for atherogenic index (AI) (except for liver and mesenteric fat) and thrombogenicity index (TI).     

The influence of feed supply time on the fatty acid profile of Nile tilapia (Oreochromis niloticus) fed on a diet enriched with n-3 fatty acids

The purpose of the study was to examine the fatty acid profiles of Nile tilapia (Oreochromis niloticus) submitted to different feeding times (0, 10, 20 and 30 days) on a diet enriched with n-3 fatty acids, by addition of flaxseed oil in substitution for sunflower oil. The main fatty acids detected were palmitic (C16:0), stearic (C18:0), oleic (C18:1n9), linoleic (C18:2n6) and -linolenic (C18:3n3) in all the treatments. The 30 day-fed fish presented the best values for total n-3 fatty acids, with a prominence of -linolenic acids, showing that the flaxseed oil as well as the feed supply time influenced the fatty acid profiles.     

The bacteriology of fresh and spoiling Lake Victorian Nile perch (Lates niloticus)

A total of 177 bacterial cultures isolated from Lake Victorian Nile Perch (Lates niloticus) were investigated. The flora on newly caught Nile perch consisted of organisms belonging to the genera Moraxella, Alcaligenes, Acinetobacter, Pseudomonas, Aeromonas, Micrococcus and other Gram-positive organisms. 39% were identified as Gram-positive species and 61% were negative in the Gram-reaction. Three cultures out of 53 investigated caused weak rotten off-odours in sterile fish broth and one culture, an Aeromonas spp. produced strong rotten, fishy, hydrogen sulphide off-odours. From Nile perch spoiled at ambient temperature, 15 of the 42 strains isolated caused rotten, fishy, hydrogen sulphide off-odours. These specific spoilage bacteria were all identified as Aeromonas and all reduced trimethylamine oxide to trimethylamine and produced hydrogen sulphide. From spoiled iced Nile perch, 74 out of 82 (90%) of the bacteria isolated were identified as Pseudomonas. A small proportion of these (13 out of 74) produced off-odours in sterile fish broth resembling the spoiling fish. These specific spoilers could not be separated from the non-spoilers based on biochemical activities used in classical taxonomy. While the Pseudomonas spp. isolated did not produce trimethylamine or H₂S, a few of the remaining isolates (two Shewanella putrefaciens and five Aeromonas spp.) did produce these compounds. The role of Shewanella putrefaciens in the iced spoilage of Nile perch was, however, insignificant, since they only very late in the storage reached numbers where their spoilage could be detected.     

The influence of diets containing either conventional corn, conventional corn with choice white grease, high oil corn, or high oil high oleic corn on belly/bacon quality

The objectives of this study were to evaluate diets possessing different fatty acid profiles (as influenced by corn type) with regard to fatty acid profile and firmness of pork bellies. Crossbred barrows (n=196) were fed one of four corn-based diets consisting of conventional corn (CONV), CONV with choice white grease (CWG), high oil corn (HOC), or high oleic, high oil corn (HOHOC). Following 98 days on test, two animals representing the average pen weight (118 kg) were selected for harvest (n=56). A 50-g fat sample was removed from each belly for fatty acid profile analysis. Lateral and vertical flex tests were performed to determine belly firmness. Bellies were pumped and cooked according to a commercial protocol. Total saturated fatty acids increased (P<0.001) and total unsaturated fatty acids decreased (P<0.05) when CWG was added to the CONV diet or when HOC or HOHOC were substituted for CONV corn. Pigs fed CONV corn had firmer bellies, while those fed HOC were softer. No differences were observed across treatment for percentage pump retention, smokehouse yield, or slicing yield (P>0.05). Based on the results of this study, corn type influences fatty acid profile, and belly firmness, but does not affect pump retention, or slicing yields.     

The bacteriology of fresh and spoiling Lake Victorian Nile perch (Lates niloticus)

A total of 177 bacterial cultures isolated from Lake Victorian Nile Perch (Lates niloticus) were investigated. The flora on newly caught Nile perch consisted of organisms belonging to the genera Moraxella, Alcaligenes, Acinetobacter, Pseudomonas, Aeromonas, Micrococcus and other Gram-positive organisms. 39% were identified as Gram-positive species and 61% were negative in the Gram-reaction. Three cultures out of 53 investigated caused weak rotten off-odours in sterile fish broth and one culture, an Aeromonas spp. produced strong rotten, fishy, hydrogen sulphide off-odours. From Nile perch spoiled at ambient temperature, 15 of the 42 strains isolated caused rotten, fishy, hydrogen sulphide off-odours. These specific spoilage bacteria were all identified as Aeromonas and all reduced trimethylamine oxide to trimethylamine and produced hydrogen sulphide. From spoiled iced Nile perch, 74 out of 82 (90%) of the bacteria isolated were identified as Pseudomonas. A small proportion of these (13 out of 74) produced off-odours in sterile fish broth resembling the spoiling fish. These specific spoilers could not be separated from the non-spoilers based on biochemical activities used in classical taxonomy. While the Pseudomonas spp. isolated did not produce trimethylamine or H₂S, a few of the remaining isolates (two Shewanella putrefaciens and five Aeromonas spp.) did produce these compounds. The role of Shewanella putrefaciens in the iced spoilage of Nile perch was, however, insignificant, since they only very late in the storage reached numbers where their spoilage could be detected.     

Fatty acid profile of olive oil extracted from irradiated and non-irradiated olive fruits

Syrian Kaissy cv olive fruit (SKOF) was irradiated (0, 1, 2, and 3 kGy). Oils were extracted from irradiated and un-irradiated olive fruits. Fatty acid profiles of Syrian Kaissy cv olive oil (SKOO) were measured by gas chromatography immediately after irradiation and after 6, 12, 24, and 36 months of storage. Results of the study showed that composition of fatty acids of SKOO were determined as palmitic (C16:0) (14.69%), palmitoleic acid (C16:1) (1.18%), stearic (C18:0) (2.19), oleic (C18:1) (68.94%), linoleic (C18:2) (12.22%), and linolenic acid (C18:3) (0.79%). The fatty acid composition of SKOO contains a healthy mixture of all the types of saturated mono-unsaturated and poly-unsaturated fatty acids. The data showed an increase (p < 0.05) in the percentage of the total saturated fatty acids and decrease (p < 0.05) in the percentage of the total unsaturated fatty acids of SKOO during storage. In general, there were no significant (p > 0.05) differences in fatty acids compositions of both oils extracted from irradiated and un-irradiated SKOF.     

野生香薷籽油脂肪酸组成及氧化稳定性研究

采用气相色谱对野生香薷籽油的脂肪酸组成进行分析测定,通过Rancimat氧化稳定性测定仪测定香薷籽油氧化稳定性,并分析比较不同抗氧化剂对香薷籽油的抗氧化效果。结果表明:香薷籽油中不饱和脂肪酸含量超过90%,其中亚麻酸含量达到58.65%;诱导期的对数与温度之间呈线性相关,香薷籽油在20℃时货架期为52.8 d,在抗氧化剂添加量相同的情况下,TBHQ的抗氧化效果最好;柠檬酸具有很好的增效作用,添加0.02%TBHQ+0.01%柠檬酸作为香薷籽油的抗氧化剂,在20℃时货架期为334.9 d,货架期延长282.1 d,抗氧化效果显著。     

澳洲坚果油脂肪酸组成及氧化稳定性分析

对6个澳洲坚果油样品进行分析的结果表明,采用气相色谱法能检测出15种脂肪酸,不饱和脂肪酸总量占比77.27%～81.02%,其中单不饱和脂肪酸含量占比74.82%～79.44%,不饱和脂肪酸主要为油酸、棕榈油酸,分别占比为60.8%～62.5%、11.3%～14.8%;在理化特征中,澳洲坚果油样品各项理化指标均符合植物油质量标准要求,其中酸价和过氧化值较低;采用烘箱法对6个样品进行加速氧化测试,温度和时间对澳洲坚果油具有较为明显的影响,温度的影响大于时间,澳洲坚果油在不同温度条件下过氧化值和酸价的变化趋势分别为60℃40℃20℃、60℃40℃20℃。     

Influence of diets enriched with flaxseed oil on the α-linolenic, eicosapentaenoic and docosahexaenoic fatty acid in Nile tilapia (Oreochromis niloticus)

This study examined the effects of different levels of flaxseed oil in increasing the α-linolenic (LNA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids contents in tilapias raised in captivity. Nile tilapia were raised in captivity for a period of five months, receiving increasing levels (0%; 1.25%; 2.50%; 3.75% and 5.00%) of flaxseed oil in substitution for sunflower oil (control). No significant differences (P>0.05) of moisture or total lipids contents were found among fillets from tilapia fed the different diets. Analyses of the fatty acid methyl esters (FAMEs) were quantitatively measured by capillary gas chromatography against a C_23:0 internal standard. Increases of the concentration of LNA, EPA and DHA (in mg/g of total lipids), were well established in the fillets, with a significant difference (P<0.05) among all the treatments, as the replacement of the sunflower oil by flaxseed oil was increased.     

Blending of corn oil with black cumin (Nigella sativa) and coriander (Coriandrum sativum) seed oils: Impact on functionality, stability and radical scavenging activity

Blends (10% and 20%, w/w) of black cumin seed oil (BCSO) and coriander seed oil (CSO) with corn oil (CO) were formulated. Oxidative stability (OS) and radical scavenging activity (RSA) of CO and blends stored under oxidative conditions (60 °C) for 15 days were studied. By increasing the proportion of BCSO and CSO in CO, levels of polyunsaturated fatty acids (PUFA) decreased, while monounsaturated fatty acids (MUFA) content increased. Progression of oxidation was followed by measuring peroxide value (PV), conjugated dienes (CD) and conjugated trienes (CT). Inverse relationships were noted between PV and OS at termination of storage. Levels of CD and CT in CO, and blends, increased with increase in time. CO:BCSO and CO:CSO blends gave 12-22% and 26-36% inhibition of DPPH radicals, respectively. Oxidative stability of oil blends were better than CO, most likely as a consequence of changes in fatty acids and tocopherols’ profile, and minor bioactive lipids (e.g., sterols and phenolics) found in coriander and black cumin oils.     

Manipulation of fatty acid composition of Nile tilapia (Oreochromis niloticus) fillets with flaxseed oil

Nile tilapia (Oreochromis niloticus) is one of the most consumed species among freshwater fish reared in Brazil. However, studies show low levels of n‐3 fatty acids in freshwater fish reared in captivity in comparison with those reared in their natural habitats. The Nile tilapia used in this study were raised in captivity for a period of 5 months and fed varying amounts (0, 1.25, 2.5, 3.75 and 5%) of flaxseed oil as a substitute for sunflower oil (control). No significant differences (P > 0.05) in total lipid (TL) content were found between fillets of tilapia fed the different diets. TL analysis of fatty acid methyl esters by capillary gas chromatography revealed a total of 50 components common to all treatments studied. The major fatty acids present were linoleic acid (18:2n‐6), oleic acid (18:1n‐9) and palmitic acid (16:0). All treatments led to significant % increases in α‐linolenic acid (18:3n‐3), eicosapentaenoic acid (20:5n‐3) and docosahexaenoic acid (22:6n‐3). Increases in both total n‐3 fatty acids and total polyunsaturated fatty acids were observed concomitantly with decreases in total n‐6 fatty acids, resulting in increases in n‐3/n‐6 ratio, with increasing level of flaxseed oil in the feed. Thus feed supplementation with flaxseed oil contributed greatly to raising the nutritional lipid value of Nile tilapia fillets. Copyright © 2007 Society of Chemical Industry     

Changes in lipids and fishy odour development in skin from Nile tilapia (Oreochromis niloticus) stored in ice

Changes in lipids, lipoxygenase activity and fishy odour development in the skin of Nile tilapia (Oreochromis niloticus) during iced storage of 18 days were monitored. Triacylglycerol content of skin decreased with coincidental increases in free fatty acid, monoacylglycerol, diacylglycerol and phospholipid contents during storage (p < 0.05). During iced storage, peroxide value increased at day 9 and subsequently decreased up to 18 days (p < 0.05). Thiobarbituric acid reactive substances values and lipoxygenase activity increased throughout 18 days of iced storage (p < 0.05). With increasing storage time, a progressive formation of hydroperoxide was found as evidenced by the increase in amplitude of peak at 3600–3200 cm⁻¹ in Fourier transform infrared spectra. Those changes indicated that lipid oxidation took place during iced storage. The increase in fishy odour of skin was observed as the storage time increased. The development of fishy odour in Nile tilapia skin during iced storage was mostly governed by lipid oxidation via autoxidation or induced by lipoxygenase. Thus, the extended storage time of whole fish resulted in the pronounced changes in lipids and the increased fishy odour in the skin.     

Oxidative stability of fish oil supplemented with carnosic acid compared with synthetic antioxidants during long-term storage

The effects of carnosic acid (CA) of different concentrations (0.1, 0.2, and 0.3 mg/g) and synthetic antioxidants on oxidative stability in fish oil stored for 66 days at different temperatures (30 and 4 °C) were compared. The investigation focused on the increase in peroxide and conjugated diene values, as well as free fatty acid and thiobarbituric acid-reactive substances. The changes in trans fatty acid and aldehyde compound contents were investigated by Fourier transform infrared spectroscopy, while the changes in polyunsaturated fatty acid content were monitored by gas chromatography–mass spectrometry. The results show that the three CA concentrations were more effective in restraining fish oil oxidation, in which a dose–response relationship was observed. The antioxidant activity of CA was stronger than that of vitamin E, but still weaker than that of tertiary-butyl hydroquinone. Fish oil supplemented with 0.2 mg/g CA exhibited favourable antioxidant effects and is preferable for effectively avoiding oxidation.     

冷榨油茶籽油的脂肪酸组成及氧化稳定性研究

以普通油茶果为原料,去壳后通过冷榨机机械压榨,得到冷榨油茶籽油,采用气相色谱法分析其脂肪酸组成,采用Rancimat法分析其氧化稳定性。研究结果表明:冷榨油茶籽油中不饱和脂肪酸含量为84.99%,其中油酸72.48%,亚油酸6.97%,α-亚麻酸2.22%;诱导期的对数与温度之间呈线性相关;在抗氧化剂添加量相等的情况下,TBHQ的抗氧化效果最好,其次是迷迭香提取物和茶多酚;使用100 mg/kg TBHQ+200 mg/kg迷迭香提取物作为冷榨油茶籽油的抗氧化剂,可使冷榨油茶籽油在120℃的诱导期延长1.88倍,抗氧化效果显著。     

Evaluation of Fatty Acid Composition,Tocols Profile,and Oxidative Stability of Some Fully Refined Edible Oils

Present study includes evaluation of fatty acid composition, tocols profile, and oxidative stability of some fully refined edible oils. Fully refined sunflower, soybean, corn, hazelnut, peanut, and canola oils were analyzed for fatty acids by capillary gas liquid chromatography, tocols by normal phase-high performance liquid chromatography and oxidative stability by rancimat. Free fatty acid, peroxide value, and iodine value of investigated oils were determined by titrimetric methods. Saturated, mono-, and polyunsaturated fatty acids were found to be in the ranges between 2.03–18.58, 23.39–77.26, and 14.39–58.52%, respectively. Tocols and oxidative stability of the investigated oils were found to be in the ranges between 488.88–913.51 mg kg^?1 and 3.05–4.99 h, respectively.     

Effect of Ganoderma lucidum (Reishi mushroom) or Olea europaea (olive) leaves on oxidative stability of rabbit meat fortified with n-3 fatty acids

The objective of the present study was to evaluate the effect of Ganoderma lucidum (Reishi mushroom) or Olea europaea (olive tree) leaves on oxidative stability of rabbit meat fortified with n-3 fatty acids. Forty-eight slovenska kunka (SIKA) rabbits were divided into four homogeneous groups. The control group ( CONT−) received diet with 6% palm fat; other groups received diet with 6% linseed oil and were either unsupplemented (CONT +) or supplemented with 1% of G. lucidum (REISHI) or O. europaea leaves (OLIVE). Rabbits were slaughtered and fatty acid composition, concentration of vitamin E and malondialdehyde (MDA) in back muscle were analyzed. The results showed that linseed oil addition improved fatty acid composition by increasing polyunsaturated fatty acid (PUFA) proportion, decreasing proportion of saturated fatty acid (SFA) and reducing n-6/n-3 ratio in rabbit meat. Groups that were supplemented with linseed oil had lower content of α-tocopherol and higher content of γ-tocopherol, compared to the CONT − group. The addition of potential antioxidants did not effectively prevent oxidation of rabbit meat.     

Fatty acid composition,oxidative stability,antioxidant and antiproliferative properties of selected cold-pressed grape seed oils and flours

Cold-pressed chardonnay, muscadine, ruby red, and concord grape seed oils and their defatted flours were studied for their fatty acid composition, oxidative stability and antioxidant and antiproliferative activities. The phenolic profiles of the seed flours were also measured. The most abundant fatty acid in the oils was linoleic acid, ranging from 66.0 g/100 g of total fatty acids in ruby red seed oil to 75.3 g/100 g of total fatty acids in concord seed oil. The oils were also high in oleic acid and low in saturated fat. Ruby red grape seed oil recorded the highest oxidative stability index of 40 h under the accelerated conditions. Total phenolic content (TPC) was up to 100 times lower in the oils than in the flours. Lutein, zeaxanthin, cryptoxanthin, β-carotene, and α-tocopherol levels were also measured. DPPH radical-scavenging capacity ranged from 0.07 to 2.22 mmol trolox equivalents (TE)/g of oil and 11.8 to 15.0 mmol TE/g of flour. Oxidative stability of menhaden fish oil containing extracts of the seed flours was extended by up to 137%. HPLC analysis was conducted to determine the levels of free soluble, soluble conjugated and insoluble bound phenolics in the seed flours. The phenolic compounds analyzed included catechin, epicatechin, epicatechin gallate, quercetin, gallic acid, and procyanidins B1 and B2. Antiproliferative activity was tested against HT-29 colon cancer cells. All of the seed flours and muscadine seed oil registered significant (P < 0.05) inhibition of cancer cell growth. The results from this study demonstrate the potential of developing value-added uses for these seed oils and flours as dietary sources of natural antioxidants and antiproliferative agents for optimal health.     

Lipid oxidation and fishy odour development in protein hydrolysate from Nile tilapia (Oreochromis niloticus) muscle as affected by freshness and antioxidants

Lipid oxidation and fishy odour development in protein hydrolysate from fresh and ice-stored Nile tilapia (Oreochromis niloticus) were investigated. During iced storage of 18 days, heme iron content decreased with a concomitant increase in non-heme iron content (P < 0.05). Peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) values increased. Phospholipid content decreased with a corresponding increase in free fatty acid content. The results suggested that lipid hydrolysis and oxidation took place during storage. When protein hydrolysates were produced from fresh and 18 days ice-stored Nile tilapia muscle, higher lipid oxidation and fishy odour/flavour along with higher amount volatile compounds were obtained in hydrolysate for unfresh sample (P < 0.05). However, the addition of mixed antioxidants during hydrolysis process markedly lowered lipid oxidation, b^∗, ΔC^∗, ΔE^∗ values, fishy odour/flavour as well as the formation of volatile compounds in the resulting hydrolysates prepared from both fresh and unfresh samples. Therefore, hydrolysate from Nile tilapia muscle with reduced fishy odour and lighter colour could be prepared by using fresh fish and incorporation of mixed antioxidants during hydrolysis.     

Fatty acid composition of seed oil of different Sorghum bicolor varieties

In order to find out new sources of premium quality edible oil in the country, seeds of ten varieties of Sorghum bicolor were initially analyzed for their total oil contents. The seed oil was later fractionated into eight fatty acids including two new saturated fatty acids. The oil contents were determined by Soxhlet method and compared with the results obtained by NMR analysis. The total oil contents in the seeds of sorghum ranged from 5.0 to 8.2 % (w/w), indicating non significant difference obtained by two different techniques. The results revealed that oleic acid (31.12–48.99%), Palmitoleic acid (0.43–0.56%), linoleic acids (27.59–50.73%), linolenic acid (1.71–3.89%), stearic acid (1.09–2.59%) and palmitic acid (11.73–20.18%) was present in the seed oil of different sorghum varieties when analyzed by GC–MS. It was observed that in most of the varieties polyunsaturated fatty acids (PUFA) were higher than monounsaturated fatty acids (MUFA). The two atypical SFAs, octanedioic (C8:0) and azelaic acid (C9:0) were found in some varieties. These results suggest that these S. bicolor varieties could be additional sources of edible oil due to presence of clinically important saturated and high concentration of unsaturated fatty acids. A large scale production of the seed oil after refining process can contribute towards alleviation of edible oil shortage in the country with increased use of premium quality oil.     

Effect of replacement of fat with sesame oil and additives on rheological, microstructural, quality characteristics and fatty acid profile of cakes

Effect of replacement of fat with 25, 50, 75 and 100% sesame oil (on fat basis); 50% sesame oil, hydrocolloids and emulsifiers on the rheological, microstructural, quality characteristics and fatty acid profile of cake was studied. Addition of increasing amount of sesame oil decreased viscosity, increased specific gravity of cake batter; decreased cake volume and overall quality score. Microstructure studies showed disrupted gluten matrix. Among the two different hydrocolloids [hydroxypropylmethylcellulose (HPMC) and xanthan] and emulsifiers [glycerol monostearate (GMS) and sodium stearoyl-2-lactylate (SSL)] tried, HPMC and SSL increased the batter viscosity, decreased the specific gravity, increased the volume and overall quality score. Use of combination of HPMC and SSL improved significantly the quality characteristics of cake with 50% sesame oil in such a way that the overall quality score was higher than that of the control cake with fat. The microstructure of cake crumb with 50% sesame oil and HPMC showed a smooth structure with less number of cavities and SSL showed a continuous protein matrix. On replacing the fat with 50% sesame oil, there was a decrease in saturated fatty acids and increase in unsaturated fatty acids, particularly linoleic acid. The fatty acid profile of cake with 50% sesame oil was better than the control cake as there was 2.4 times decrease in palmitic acid content and 5.9 times increase in essential fatty acids (EFA) content.