A comparison of selected methods for determining eicosapentaenoic acid and docosahexaenoic acid in cereal-based foods

The accuracy of four transesterification methods and four extraction methods for determining the eicosapentaenoic acid and docosahexaenoic acid contents of cereal-based foods enriched with fish oil containing these fatty acids was investigated. The four enriched test foods were a flaked breakfast cereal, a snack bar, bread and muffins. The accuracy of the transesterification methods was tested using several commercial fish oils. The recovery of eicosapentaenoic acid and docosahexaenoic acid in the fish oils ranged from 97% to 104% depending on the transesterification method used. For the extraction methods, the recovery of eicosapentaenoic acid and docosahexaenoic acid across all food products ranged from 59% to 101% and 74% to 98% respectively depending on the extraction method used. Overall, the solvent mixture direct method was the most accurate extraction method across all the foods. However, the application of different extraction methods for different food types may be optimal when accurate analysis of eicosapentaenoic acid and docosahexaenoic acid in foods is required.     

Optimization of the GC method for routine analysis of the fatty acid profile in several food samples

The fatty acids profile of food samples was determined by gas chromatography (GC). The fat was extracted from different food samples using Soxhlet technique. Extracted triglycerides were converted to corresponding methyl esters using methanolic solution of potassium hydroxide (trans-esterification). GC method for the analysis of obtained methyl esters was optimized on two different cyanopropyl capillary columns. Good resolution of all fatty acids commonly found in foodstuffs was achieved. After optimization, the method was validated and the results for linearity, precision, limit of quantitation (LOQ), limit of detection (LOD), robustness and stability were presented. The method has been applied to the quantitative determination of the fatty acid content in different food samples: edible oil, dairy products rich with omega-3 fatty acids, different food supplements, baby food, etc.     

蔗糖脂肪酸酯的合成及应用

蔗糖脂肪酸酯是蔗糖的深加工产物，介绍了蔗糖酯的性质、合成方法和应用。蔗糖酯是一种良好的非离子表面活性剂，有着广泛的用途，它的应用领域还在不断开发；蔗糖聚酯是新型的低热量油脂，可作为脂肪代用品及高血脂、高胆固醇的治疗预防药物。     

The fatty acid composition of the lipids of earthworms.

Lipids were freshly extracted from earthworms from agricultural pasture land, and fatty acid compositiona analyses were carried out on the total lipids; phospholipids; triglycerides; free fatty acids; mixed sterol esters, wax esters, free methyl esters, etc.; glycolipids; and neutrallipids. A wide variety of fatty acids ranging from C₁₀ to C₃₂ were identified. In the fatty acids of the total lipids, polyunsaturated constituents predominated in amount, while monomethyl branched, isoprenoid and n-odd-numbered acids were present in appreciable proportions. Eicosa-5,8,11,14,17-pentaenoic acid and arachidonic acid occurred at higher levels than any other components and were located mostly in the phospholipids. Significant contents of linoleic and linolenic acids were also detected. Earthworms collected in spring had a fatty acid composition which differed noticeably from that of worms from other seasons. The content of lauric acid during spring was much higher than that normally found in animals or pasture plants. The composition of the free fatty acids indicated that these components were the products of lipolysis and were derived from all the lipid classes. The results of this investigation suggest that the diet of local earthworms, which is reported to consist mainly of dead plant material, is supplemented by living and dead microorganisms from ingested soil.     

SELECT NUTRIENT COMPARISON OF IMITATION SHELLFISH WITH REAL SHELLFISH

Select nutrients of three real shellfish, three imitation surimi based shellfish, and two imitation soy based shellfish were measured by gas chromatography, high pressure liquid chromatography and AOAC methods. The lipid was extracted, methylated and analyzed on a wide bore capillary column with temperature programming to separate the fatty acid methyl esters. Carbohydrates were analyzed isocratically by high performance liquid chromatography on a polar column. Sodium and potassium were analyzed by atomic absorption spectrophotometry. AOAC methods were used to determine percent moisture, protein, and fat. Analysis of variance for the select nutrients showed significant differences among the imitation and real shellfish products (P 0.05) for sodium, potassium, carbohydrate, moisture, fat and protein content. Significant differences were also present in the fatty acid methyl ester analysis. The data suggested that the imitation shellfish products differed significantly in nutrient content from the corresponding real shellfish.     

无溶剂直接酯化法合成亚油酸甾烷醇酯的研究

为了得到甾烷醇与亚油酸在无溶剂条件下,直接酯化法合成亚油酸甾烷醇酯的最佳工艺条件,以酯化率和体系氧化程度为考察指标,单因素考察筛选利于合成的底物酸醇摩尔比、催化剂添加量、反应温度和反应时间,并采用L9(34)正交实验进一步优化得出最佳合成工艺:亚油酸与甾烷醇的摩尔比3∶1,催化剂用量3%,反应时间5h,反应温度150℃,在此条件下,亚油酸甾烷醇酯的酯化率达到81.23%。采用薄层色谱,高效液相色谱和近红外光谱对亚油酸甾烷醇酯进行了鉴定,并研究了亚油酸甾烷醇酯的热力学特性。     

Synthesis, characterization and application of polyglycerols and polyglycerol fatty acid esters

The current state of knowledge in the field of synthesis and properties of polyglycerols and polyglycerol fatty acid esters is presented. Alternatives for the analytical characterization of these families by means of physico-chemical methods, with special reference to chromatography and spectroscopy, are described. Furthermore, the use of polyglycerol fatty acid esters as food additives is considered from the view-points of the physiology of nutrition and of processing technology.     

竹柏种仁油脂成分及其抗氧化活性分析

采用5种方法对竹柏种仁油脂进行提取,并通过核磁共振和气相色谱-质谱技术分别对其油脂成分和脂肪酸组成进行分析,同时采用DPPH自由基清除法和羟基自由基清除法对竹柏种仁油脂的抗氧化活性进行研究。结果表明,5种方法对竹柏种仁油脂的提取率存在显著差异(P 0.05),其中Folch法的提取率最高,为53. 81%。竹柏种仁油脂以甘油三酯为主,磷脂、游离脂肪酸和甾醇含量极低。竹柏种仁油脂经2 mol/L KOH-甲醇溶液室温衍生3 min,甲酯转化率即达99. 80%;且其脂肪酸以油酸(18. 65%)、亚油酸(43.49%)和花生烯酸(30.65%)为主,不饱和脂肪酸含量高达90%以上。竹柏种仁油脂对DPPH自由基和羟基自由基的IC_(50)分别为3.36 mg/mL和0. 38 mg/mL,表明竹柏种仁油脂具有较好的抗氧化能力,可作为健康植物油脂进行开发利用,具有良好的开发潜力和应用前景。本研究为竹柏种仁油脂的提取、成分分析和抗氧化活性研究提供了一定的参考。     

Beef, chicken and lamb fatty acid analysis - a simplified direct bimethylation procedure using freeze-dried material

When fractionation of meat lipids is not required, procedures such as saponification can be used to extract total fatty acids, reducing reliance on toxic organic compounds. However, saponification of muscle fatty acids is laborious, and requires extended heating times, and a second methylation step to convert the extracted fatty acids to fatty acid methyl esters prior to gas chromatography. Therefore the development of a more rapid direct methylation procedure would be of merit. The use of freeze-dried material for analysis is common and allows for greater homogenisation of the sample. The present study investigated the potential of using freeze-dried muscle samples and a direct bimethylation to analyse total fatty acids of meat (beef, chicken and lamb) in comparison with a saponification procedure followed by bimethylation. Both methods compared favourably for all major fatty acids measured. There was a minor difference in relation to the C18:1 trans 10 isomer with a greater (P<0.05) recovery with saponification. However, numerically the difference was small and likely as a result of approaching the limits of isomer identification by single column gas chromatography. Differences (P<0.001) between species were found for all fatty acids measured with no interaction effects. The described technique offers a simplified, quick and reliable alternative to saponification to analyse total fatty acids from muscle samples.     

牦牛乳脂肪酸组成分析

乳脂的营养价值很高,牦牛乳中含有大量的脂肪酸,主要脂肪酸为辛酸、月桂酸、肉豆蔻酸、十五碳酸、棕榈酸、棕榈油酸、珍珠酸、硬脂酸、油酸、亚油酸、亚麻酸.目前脂肪的提取方法和甲酯化方法没有确定统一的方案,本研究对牦牛乳采用不同的脂肪提取方法和甲酯化方法,旨在找到分析牦牛乳中主要脂肪酸的最佳方案.乳脂肪酸的组成直接影响乳的营养、风味以及加工品质,乳脂肪酸功能及乳脂肪酸组成的调控成为当前反刍动物营养研究的热点,因此分析牦牛乳中脂肪酸的组成,对于认识其营养价值具有重要意义.     

微生物油脂中氯丙醇酯的形成及应对措施综述

氯丙醇及其酯类是国际社会广泛关注的食品污染物之一,近年来发现氯丙醇酯广泛存在于各种食用油脂及含油脂食品中,而引起油脂行业的广泛关注。本文较为详细的总结了目前国内外对油脂中氯丙醇酯的毒性、检测方法、形成机制及控制方式等的研究现状,并对微生物油脂中可能的产生机制和应对措施进行了概述,以指导微生物油脂及食品的生产和消费,推动我国微生物油脂食品的健康发展。     

气相色谱-内标法测定白酒中3种高级脂肪酸乙酯含量

以乙酸正戊酯为内标物,建立了白酒中棕榈酸乙酯、油酸乙酯和亚油酸乙酯的气相色谱-内标法检测方法,并对市售不同香型白酒、不同品牌酱香型白酒中3种高级脂肪酸乙酯的含量分布规律进行探究。结果表明,3种高级脂肪酸乙酯的分离效果良好,线性范围为0.300 0～0.400 0 mg/mL,相关系数(R²)均>0.999,精密度试验结果相对标准偏差(RSD)<5%,加标回收率为94.01%～116.97%,检出限为0.003 2～0.003 5 mg/mL,定量限为0.010 9～0.011 7 mg/mL。11种不同香型白酒样品的3种高级脂肪酸乙酯含量在0～0.062 2 mg/mL之间,其中,酱香型白酒含量最高(0.062 2 mg/mL);35种不同品牌酱香型白酒中3种高级脂肪酸乙酯总含量在0.003 5～0.075 8 mg/mL之间。该方法准确、灵敏度高,能对白酒中3种高级脂肪酸乙酯进行有效的分析,可用于酒类企业日常白酒分析检测。     

Fatty acid composition of rice oils.

Analysis of rice oil methyl esters of two varieties by gas-liquid chromatography showed that oil from bran-polish and oil from milled rice extracted with petroleum ether had similar fatty acid composition and had oleic/linoleic acid ratios of about 1.0. However, milled rice oil extracted with chloroform/methanol had a higher linoleic acid content and a lower oleic acid content than oil extracted with petroleum ether.     

聚甘油脂肪酸酯的合成及其整理性能研究

用甘油和各种脂肪酸为原料制得聚甘油和相应系列的聚甘油脂肪酸酯,并测试、表征了合成产品的基本性能。将合成产品调制成平滑整理剂对织物进行整理,分析、比较了不同聚合度、脂肪酸、整理剂浓度对织物平滑性能的影响,最终获得了平滑整理效果好的产品结构信息。     

基于植物油中脂肪酸烷基酯含量变化鉴别废弃油脂

采用固相萃取柱净化,气相色谱-质谱联用法测定了6种植物油中脂肪酸烷基酯(包括脂肪酸甲酯和脂肪酸乙酯)的含量,并研究其在植物油煎炸、废弃及废弃油脂精炼等环节中的变化。结果发现,6种植物油中脂肪酸烷基酯的含量均低于30 mg/kg,而植物油在废弃过程中可能会形成大量脂肪酸乙酯,生成量与油脂是否烹饪及废弃物中乙醇含量有关。脂肪酸烷基酯在脱色工艺中不能被去除,但在脱臭中可被去除。因此,可以通过测定植物油中脂肪酸烷基酯含量发现废弃油脂,为废弃油脂的鉴别工作提供新的思路。     

An investigation of presence of 2- and 3-monochloropropanediol fatty acid esters in Canadian human milk samples

ABSTRACT

Occurrence of 2- and 3-monochloropropanediol fatty acid esters (MCPDEs) in 199 human milk samples collected from Canadian women was examined in this study. MCPDEs were determined via indirect analytical approach by using acidic hydrolysis/transesterification and derivatization with cyclohexanone using a fluorinated sulfonic acid resin as a catalyst followed by GC-MS analysis. Analyses were done by a stable isotope dilution assay (SIDA) using 3-monochloropropanediol-d₅ dipalmitate and 2-monochloropropanediol-d₅ distearate as internal standards. In all samples 2-MCPD esters were not detected, at LOD = 1 ng/g for 2-MCPD equivalent. 3-MCPD esters were not detected, at LOD = 2 ng/g for 3-MCPD equivalent, in 193 samples. Six samples had the apparent concentration of 3-MCPD equivalent in the range of 2.0–5.1 ng/g, which was likely caused by accidental contamination during processing of samples. For selected samples, these findings were confirmed by direct analysis via LC-MS/MS analysis based on SIDA for 3-MCPD dipalmitate and 2-MCPD distearate. To our best knowledge, this is the first study to analyze human milk samples for 2-MCPD esters.     

Lard uptake and its detection in selected food products deep-fried in lard

Analytical methods for the detection of both pork and lard in food products are in great demand for regulatory purposes. Means of identifying food products fried in lard has been investigated in this study. Four fat containing products namely, peanuts, tempeh (fermented soybean cake), chicken and beef were subjected to deep-fat frying using lard as the frying medium. Oils extracted from the control and fried samples were analyzed by gas liquid chromatography (GLC), high performance liquid chromatography (HPLC) and differential scanning calorimetry (DSC). In this way, changes in composition and thermal profiles during frying were examined. Results showed that palmitic acid enrichment factor (PAEF) calculated from GLC analysis of fatty acid methyl esters seems to be a useful parameter in determining lard contamination in all four fried products. With the triglycerol (TG) profiling by HPLC it was possible to detect lard in fried chicken and tempeh products while DSC cooling and heating traces were found to be useful for lard detection in fried tempeh, chicken and beef products.     

A novel chemoenzymatic synthesis of phytosteryl caffeates and assessment of their antioxidant activity

Phytosterols and their derivatives are relevant in food, pharmaceuticals, and cosmetics. In addition to their well-known effect in lowering low-density lipoprotein (LDL) cholesterol, they also possess other biological activities, such as anti-inflammatory, anti-atherogenicity, and anti-carcinogenic potential. A novel method was developed for chemoenzymatic synthesis of phytosteryl caffeates through an intermediate vinyl caffeate, which was first chemically produced and subsequently esterified with phytosterols through lipase-assisted alcoholysis. The structures of the phytosteryl caffeates were confirmed by infrared (IR) and high performance liquid chromatography–mass spectrometry/mass spectrometry (HPLC–MS/MS). The ORAC values of phytosteryl caffeates were two times higher than that of caffeic acid. In a meat model system, the antioxidant activity of phytosteryl caffeates was higher than caffeic acid and vinyl caffeate, and that of butylated hydroxyanisole (BHA), a commonly used synthetic antioxidant. The results indicate that phytosteryl caffeates have a good potential for use as food antioxidants.     

柞蚕(幼虫)中脂肪酸的初步分析

研究了脂肪油的衍生化、三氟化硼、硫酸3种不同方法对脂肪油的皂化、甲酯化效果,并用GC/MS法对柞蚕中脂肪酸的成分进行了鉴定和分析.结果表明：硫酸甲酯化效果较好;柞蚕中含有大量人体所必需的不饱和脂肪酸,其中以油酸、亚油酸、亚麻酸等为主,它们的含量分别为41.85%、4.73%和13.19%.     

Validation of the sensitive and accurate quantitation of the fatty acid distribution in bovine milk

A method for the precise analysis of the complex mixture of fatty acids in milk has been developed and validated. The triacylglycerol of nonanoic acid was applied as the internal standard (ISTD) for absolute quantification. Milk lipids were extracted by miniaturised ultrasonication and methylated with trimethylsulfonium hydroxide. Resulting fatty acid methyl esters were determined by gas chromatography with flame ionisation detection giving excellent resolution, including separation of several 18:1 isomers. The low quantitation limit (0.01 mg mL⁻¹ milk) indicates that the sensitivity of the method is sufficient to quantify up to 50 fatty acids, from 4:0 to 23:0. Measurements of precision provided excellent results for different bovine milk samples of different fat content (coefficient of variance: 1.9% and 9.8% for intra- and interday precision, respectively). Recovery averaged 108 ± 3.5%. Evaluation of methods for determining the total fat content showed that gravimetry is no longer needed when using the ISTD.