GC-MS quantification of fatty acid profile including trans FA in the locally manufactured margarines of Pakistan

Ten margarine brands of Pakistan were analyzed for their fatty acid composition with emphasis on trans fatty acids (TFA) using GC-MS. Saturated, cis-monounsaturated and polyunsaturated fatty acids were present at 24.2–58.1, 5.7–35.4 and 3.8–37.4% of total fatty acids, respectively. Among the saturated fatty acids, palmitic acid (16.9–33.8%) was dominant in all analyzed margarine brands and its higher amount indicates that palm oil was a major contributor in the margarine manufacturing. Among samples tested only one contained a low level of TFA (2.2%) while the rest contained very high amounts of TFA (11.5–34.8%) which clearly shows that hydrogenated oils were used in the formulation of margarines. Fatty acid profiles demonstrated that all samples belong to the hard margarine category containing high amounts of trans and saturated fatty acids which is an alarming issue for the health of consumers.     

Analysis and formation of trans fatty acids in hydrogenated soybean oil during heating

Hydrogenated oil has been widely used for production of shortenings or margarine, however, the presence of trans fatty acids may be detrimental to human health. The objectives of this study were to develop an improved method for analysis of trans fatty acids and evaluate their formation in both unhydrogenated and hydrogenated soybean oil during heating at 160, 180 and 200 °C for varied length of time. Results showed that among the four columns tested, an Agilent HP-88 column (100 × 0.25 mm I.D., 0.2-μm film thickness) could resolve eight trans fatty acids and nine cis fatty acids simultaneously within 31 min with injector temperature 240 °C, detector temperature 250 °C, and column temperature 170 °C in the beginning, maintained for 24 min, increased to 220 °C at 7.5 °C/min, 230 °C at 10 °C/min, and maintained for 5 min. The contents of both cis and trans fatty acids showed a decreased trend for the increase of heating time or temperature. No trans fatty acid formation was observed even after extensive heating of unhydrogenated and hydrogenated soybean oil for 24 h. This phenomenon demonstrated that trans fatty acids can only be formed under severe conditions.     

Identification and quantification of trans fatty acids in bakery products by gas chromatography–mass spectrometry after focused microwave Soxhlet extraction

Trans fatty acids have been determined in fourteen bakery products using derivatisation by ester formation, gas chromatography–mass spectrometry for individual separation and identification/quantification following total fat isolation by Soxhlet extraction accelerated by focused microwave irradiation at the cartridge zone. The detection and quantification limits between 0.98 and 3.93 and 3.23–12.98 μg g⁻¹, respectively, and the linear dynamic ranges between LOQs values and 12,000 μg g⁻¹ thus obtained, demonstrated the utility of the approach for this type of analysis thanks to the wide determination range and high information level it provides. The proposed extraction method, which was validated by comparison with the Folch reference method – extraction under very mild conditions, shows that no changes of the original fat are produced under microwave-assisted extraction. The much shorter extraction time – 35 or 60 min vs. 3.5 h of the Folch method – and similar characteristics of the extract make this method an excellent alternative for the treatment of solid samples prior to trans fatty acids analysis. The target analytes were determined in fourteen bakery products; thus supporting the validity of the overall process.     

Synthesis of cyclopropane fatty acids in Lactobacillus helveticus and Lactobacillus sanfranciscensis and their cellular fatty acids changes following short term acid and cold stresses

An implemented GC method to separate and quantify the cell cyclopropane fatty acids lactobacillic (C19cyc11) and dehydrosterculic (C19cyc9) was used to study the adaptive response to sublethal acid and cold stresses in Lactobacillus helveticus and Lactobacillus sanfranciscensis. The comparison of the composition of cellular fatty acids of the two strains and their changes after 2 h of stress exposure under micro-aerobic and anaerobic conditions indicated that the aerobic biosynthetic pathway for unsaturated fatty acids is prevalent in L. sanfranciscensis, while the anaerobic pathway is prevalent in L. helveticus. Indeed in the latter strain, in the presence of a source of oleic acid and under micro-aerobic conditions, C18:1n11 and its post-synthetic derivative C19cyc11 accounted for overall proportion ranging from 52 to 28% of the total FAs. On the other hand L. sanfranciscensis synthesizes by aerobic pathway C18:1n9 and transforms it to C19cyc9. However in this species the cumulative level of these two FAs did not exceed 30%. The relevant proportion of dodecanoic acid in the latter species suggests that carbon chain shortening is the principal strategy of L. sanfranciscensis to modulate fluidity or chemico-physical properties of the membranes.     

A simple method for the analysis of trans fatty acid with GC–MS and AT-Silar-90 capillary column

The study was aimed to evaluate a simplified gas chromatography method based on the AOAC method 996.06 to analyze the trans fat content in food samples. The gas chromatograph was equipped with mass spectrometer and Alltech AT^™-Silar-90 capillary column. Ten kinds of the trans fatty acid standard were separated completely from the cis standard and the chemical composition of the peaks was verified by using the mass spectrum. Under the optimized conditions, the recovery rate for triheptadecanoin was 99.0%, the correlation coefficients of trans fatty acid calibration curve was 0.9998 or higher. It demonstrated that the methylation and hexane extraction procedures used in this method was effective and the result was consistent. The major fatty acids found in the shortening sample were 16:0, 18:0, trans-18:1, cis-18:1, cis-18:2, and cis-18:3. The total trans fat content in the sample was 283.6 ± 18.2 mg/g. The current method was more convenient. It is adequate for the routine analysis of trans fat content in food products with low free fatty acid content.     

Application of transmission FT-IR spectroscopy for the trans fat determination in the industrially processed edible oils

The amount of trans fatty acids (TFA) in fourteen industrially hydrogenated and deodorized oils was determined. To achieve better sensitivity 200 μm KCl cell was used in transmission Fourier transform infrared (FT-IR) spectroscopy. The results of transmission FT-IR spectroscopy were evaluated by gas chromatography (GC) with flame ionization detector (FID), and found to be comparable. All analyzed cooking oil samples had a lower trans content of 0.4–1.8%. Trans fatty acid contents of partially hydrogenated oil samples were relatively higher as comparable to those of the cooking oils. Among the samples examined, the highest level was found to be at 26.5% and 25.7% by the GC–FID and FT-IR spectroscopy, respectively. Due to harmful effects, high amounts of trans fatty acids in partially hydrogenated oils is an alarming issue for the consumer’s health and quality control authorities.     

The composition of fatty acids in the tissues of Tunisian swordfish (Xiphias gladius)

The objective of this study was to compare the composition of fatty acids stored in the various parts of swordfish. Muscle and organ sections of a series of swordfish samples were collected. Their chemical analysis allowed the classification of swordfish as a semi-fatty fish, with its byproducts totalling 35.6% of the total fatty acids (TFA) and its white and red muscles (MR) 7.2%. The highest contents were found in the liver (26%), the gonads (4.7%) and the red muscle (RM) (4.5%). The UFA/SFA ratio as recommended by nutritionists is 3; in the liver, skin and RM samples this ratio was, respectively, 3.5, 2.8 and 2.7. There is a high level of unsaturated fatty acids (UFA) in swordfish. More than 40% of the muscular tissues are made up of polyunsaturated fatty acids (PUFA) of the n-3 series (EPA + DHA). The byproducts contain more than 30% of monounsaturated acids characterised by the fatty acids of the n-9 series and particularly by oleic acid.     

Conjugated linoleic acid production by cells and enzyme extract of Lactobacillus delbrueckii ssp. bulgaricus with additions of different fatty acids

The objective of the study was to determine the effect of fatty acid additions to the cells and enzyme extract of Lactobacillus delbrueckii ssp. bulgaricus (CCRC14009) on CLA production. Washed cells of L. delbrueckii ssp. bulgaricus, obtained by cultivation in a MRS broth, were mixed with BSA and each of the three fatty acids: linoleic, oleic, and linolenic acids in sodium phosphate buffer at pH 6.5. After incubation at 37 °C for 108 h, CLA concentration was analyzed by HPLC. Enzyme extract from the culture was also reacted with each fatty acid at 50 °C for 10 min at pH 5 to test for CLA production. Results showed that linoleic acid addition to the culture improved CLA production, indicating the presence of linoleic acid isomerase activity in the culture. The crude enzyme extract from the culture was observed to be capable of oleic and linolenic acid conversions into CLA, demonstrating the possible presence of desaturase activity in the enzyme extract.     

n‐3 Omega fatty acids: a review of current knowledge

The very long chain polyunsaturated fatty acids (PUFAs) (C18–C22) and n‐3 Omega PUFAs are apparently widely accepted as a part of modern nutrition because of their beneficial effects on metabolism. Most significantly, the reported protective effect of the n‐3 omega fatty acids in relation to cardiovascular inflammatory diseases and cancer has led people to consider these fatty acids more beneficial than other dietary supplements. Unfortunately, there is a lack of studies relating to the physical performance increasing effect in sports diets, cholesterol‐reducing effect in meat technology, effects on human serum profile, the application dose and the side effects with/without omega‐6 PUFAs, which has left us with several crucial unanswered questions. We still do not know the correct dose of n‐3 omega and the correct ratio of n‐3 omega to n‐6 omega or their possible contraindications when combined with drugs, other foods and herbal supplements. Another reported aspect of n‐3 omega PUFAs is that they protect and even enhance the effect in medical treatment of important diseases such as Alzheimer’s, multiple sclerosis and cancer. These reports led to PUFAs becoming one of the most accepted and consumed food supplements. Despite this weight of evidence and the considerable current use, there is still a need for studies, which will determine whether the n‐3 omega fatty acids are in fact important functional supplements with no adverse effects. This review will attempt to outline the current position of n‐3 omega fatty acids in the field of clinical nutrition and healthcare and outline the studies needed to determine whether there are significant advantages in taking them as food supplement without any adverse effects.     

Direct quantification of fatty acids in dairy powders with special emphasis on trans fatty acid content

In this study a validated procedure for accurate determination of fatty acids in dairy products, with special emphasis on total trans fatty acids (TFA) content is presented. Dairy fat naturally contains 4–6% of trans fatty acids, mainly trans-octadecenoic acids (i.e. vaccenic acid), and 0.3–1.5% of conjugated linoleic acids (CLA). The proposed procedure does not require lipid extraction, and transesterification of lipids could be carried out directly on dairy products. Optimal analytical conditions have been developed to allow accurate determination of TFA content without prior fractionation of cis/trans FAME isomers by thin-layer chromatography. The methodology requires the use of a highly polar open tubular capillary column having at least 100 m length. CLA and other fatty acids from C4:0 (butyric) acid to long-chain polyunsaturated fatty acids (LC-PUFAs) could also be analyzed. Therefore, the methodology presented is versatile and could be used for both targeted analysis (e.g. determination of TFA in dairy products) and determination of the broad fatty acid profile in dairy products.     

Seasonal changes of fatty acids of cuttlefish Sepia officinalis L. (Mollusca: Cephalopoda) in the north eastern Mediterranean sea

The total lipids and seasonal variations in the fatty acids of the mantle of cuttlefish (Sepia officinalis) captured in the north eastern Mediterranean were investigated and the mantle was found to be a good source of polyunsaturated fatty acids (ω3 PUFAs, in particular). In all seasons, the major fatty acids in the cuttlefish mantle were observed to be palmitic acid (16:0), stearic acid (18:0), eicosapentaenoic acid (EPA, 20:5ω3) and docosahexaenoic acid (DHA, 22:6ω3). A comparison of the saturated fatty acid (29.5–36.8%), monounsaturated fatty acids (7.81–9.84%) and polyunsaturated fatty acids (43.7–49.6%) of the cuttlefish mantle revealed that polyunsaturated fatty acids (PUFA) constituted the highest proportion. The levels of DHA in the cuttlefish mantle in autumn, winter, spring and summer were 27.6%, 28.5%, 29.5% and 23.9%, while those of EPA were 16.8%, 15.4%, 14.7% and 13.9%, respectively.     

不同类型膳食脂肪酸对肥胖小鼠肝脏及其血液中脂肪酸组成和代谢相关基因影响

目的探讨不同类型膳食脂肪酸对肥胖小鼠肝脏及其血液中脂肪酸组成及代谢相关基因的影响。方法 8周龄雄性C57BL/6小鼠随机分为7组,即对照组(喂基础饲料)、长链饱和脂肪酸(LCSFA)组(喂猪油高脂饲料)、中链饱和脂肪酸(MCSFA)组(喂椰子油高脂饲料)、n-3多不饱和脂肪酸(n-3 PUFA)组(喂亚麻籽油高脂饲料)、n-6多不饱和脂肪酸(n-6 PUFA)组(喂大豆油高脂饲料)、单不饱和脂肪酸(MUFA)组(喂橄榄油高脂饲料)和反式脂肪酸(TFA)组(喂8%氢化大豆油高脂饲料),每组10只,共干预16周,所有种类饲料总能量均相同,基础饲料脂肪供能比为10%,各高脂饲料脂肪供能比均为45%,喂养周期结束后,禁食12 h,麻醉后立刻解剖取出肝脏。采用气相色谱法分析肝脏及其血液中脂肪酸组成的变化,实时荧光定量聚合酶链式反应(PCR)检测肝脏脂肪酸代谢相关基因的表达,肝脏脂质沉积采用油红O染色法检测。结果与对照组比较,LCSFA组、MCSFA组、n-6 PUFA组、MUFA组和TFA组小鼠肝脏中均出现明显的脂质沉积,n-3 PUFA组小鼠肝脏未出现明显的脂质沉积。与对照组比较,LCSFA组小鼠肝脏及血液中总n-6 PUFA和总PUFA含量升高; n-3 PUFA组小鼠肝脏及血液中总n-3 PUFA和总PUFA含量增加,但总MUFA含量减少; n-6 PUFA组小鼠肝脏及血液中总n-6PUFA、总n-3 PUFA和总PUFA含量升高,但总饱和脂肪酸(SFA)和总MUFA含量降低; MUFA组小鼠肝脏及血液中总SFA含量减少; TFA组小鼠肝脏及血液中C18∶1 n-9t(TFA)含量升高;以上差异均有统计学意义(P0. 05)。LCSFA组和MCSFA组小鼠肝脏脂肪酸代谢基因固醇调节元件结合蛋白1(SREBP-1c) mRNA水平高于对照组和n-6 PUFA组,差异均有统计学意义(P0. 05)。结论小鼠肝脏及其血液中脂肪酸构成与其对应的膳食脂肪酸模式一致。不同类型脂肪酸高脂饲料可通过对相关基因的表达影响肥胖状态下肝脏的脂质代谢及脂质沉积。     

Effect of weaning status on lipids of Galician Blond veal: Total fatty acids and 18:1 cis and trans isomers

The effect of weaning at different ages (NW = not weaned, W5 = 5.5 months and W2 = 2 months) on fatty acids (FA) of the Longissimus thoracis (LT) muscle was studied in 36 Galician Blond (GB) calves. Total FA (TFA) were determined by gas chromatography (GC) and 18:1 isomers by a combination of reversed-phase high performance liquid chromatography (HPLC) and GC. NW group showed higher (P < 0.001) values of n-3 polyunsaturated FA (PUFA), conjugated linoleic acid (CLA) and 18:1trans-11 compared to LT from W5 and W2 calves. W2 calves showed the highest levels of n-6 PUFA (P < 0.01), 18:1trans-10 and 18:1trans-6/7/8 (P < 0.001). Generally, W5 calves had intermediate values for TFA and 18:1 isomers. As the suckling period was longer, GB milk and veal FA profiles became more similar, it seems that muscle FA were partially transmitted by the milk FA intake due to the persistence of the reticular grove closing reflex.     

Identification of the composition of fatty acids in Eucommia ulmoides seed oil by fraction chain length and mass spectrometry

In order to automatically identify fatty acids in plant seed oils, a method was developed to search all saturated fatty acid methyl esters in the sample, subsequently calculate the ECL value of each fatty acid, and finally identify the molecular structure for each component by comparing the ECL of the interest and that in the customised database. Our method was applied to analyse the fatty acid composition of Eucommia ulmoides seed oil. The results show that major polyunsaturated fatty acids are α-linolenic acid (56.5093% of total fatty acids, TFAs) and linolelaidic acid (12.6563% of TFAs). Meanwhile, the main monounsaturated fatty acid is oleic acid whose percentage in the TFAs is 15.8008. Palmitic acid and steartic acid are the dominant saturated fatty acids representing 9.8165% and 2.5942% of TFAs, respectively. The UFA/SFA ratio (6.57) is higher than the recommended value (3) by nutritionists.     

食品中反式脂肪酸的风险评价

根据风险评价理论,从反式脂肪酸来源、吸收代谢方式、对人体健康的危害及中国居民膳食调查和各种食品中反式脂肪酸暴露水平,推算出现在中国居民反式脂肪酸暴露量低于安全摄入剂量,表明中国食品中反式脂肪酸风险尚属可接受范围;最后从降低食物中反式脂肪酸、建立反式脂肪酸的标签制度及实施限量标准两方面提出了风险管理措施。     

Supercritical carbon dioxide extraction of polyunsaturated fatty acids from Northern shrimp (Pandalus borealis Kreyer) processing by-products

This study investigated the potential of Northern shrimp (Pandelus borealis Kreyer) by-products as a source of omega-3 polyunsaturated fatty acids (ω-3 PUFAs). The by-products (heads, shell and tail) of processing accounted for approximately 50–60% of the catch. Supercritical CO₂ extraction (SFE) of the by-products at 35 MPa and 40 °C generated a deep red oil, rich in ω-3 PUFAs, specifically 7.8 ± 0.06% eicosapentaenoic acid (EPA) and 8.0 ± 0.07 % docosahexaenoic acid (DHA).     

一步提取测定食品中的脂肪酸

建立了一步提取测定食品中脂肪酸的检测方法。乙酰氯与甲醇反应得到的盐酸-甲醇使试样中的脂肪和游离脂肪酸甲酯化,用甲苯提取后,氢火焰离子化检测器检测。各脂肪酸甲酯标准溶液在0.005～1mg/mL范围内呈线性相关(r=0.999);在不同基质中各脂肪酸回收率为82.1%～100%,相对标准偏差RSD<10%;各脂肪酸检出限为1mg/100g。一步提取测定脂肪酸操作方便、快速,灵密度高,可满足食品中脂肪酸测定的要求。