基于脂肪酸差异的肉制品中猪源性成分鉴别方法的研究

建立了肉制品中脂肪酸的分析检测技术,通过分析脂肪酸含量、种类以及片段特征指纹图谱,实现了基于脂肪酸差异的肉制品中猪源性成分的鉴别。采用气相色谱法测定了大量肉制品,利用保留时间和质谱鉴定了36种脂肪酸成分,选取较为稳定的18种脂肪酸数据进行统计分析,确定不同油脂脂肪酸的差异,结合特征图谱,最终确定可用于鉴别猪源性成分的8种脂肪酸。该方法可用于确定肉制品中是否含有猪源性成分,方法简单、快速、成本低,辨别度较高,在猪源性成分鉴别中具有一定的应用前景。     

Chemometric Analysis of Fatty Acid Composition of Raw Chicken,Beef, and Pork Meat with Plant Extract Addition during Refrigerated Storage

During the shelf-life, meat undergoes a number of processes that negatively affect the quality of the product, including fatty acid composition. The application of various plant extracts in meat could affect the changes of fatty acids during storage. Thus, the aim of this study was to investigate the effect of various spice and herb extracts on fatty acid composition in raw pork, beef, and chicken meat when stored at 4 °C for 13 days. Based on multivariate statistical analysis, two datasets were extracted from each type of meat. One dataset included samples with allspice, bay leaf, black seed, cardamom, caraway, clove, and nutmeg with the high share of total MUFA (monounsaturated fatty acids) in chicken and pork meat and high MUFA and PUFA (polyunsaturated fatty acids) contribution in beef meat after storage. The second dataset included basil, garlic, onion, oregano, rosemary, and thyme with high PUFA share in chicken and pork meat and high SFA (saturated fatty acids) contribution in beef meat. From the regression analysis, a significant effect of time on fatty acid composition in meat was reported. Generally, the rates of fatty acid changes were dependent on the plant extract incorporated into the meat. The most visible effect of plant extracts was obtained in chicken meat. In chicken meat with plant extracts, the rates of SFA and PUFA changes with time were slower compared to the control sample. In summary, the fatty acid composition of intramuscular fat varied during storage, and the addition of plant extracts significantly affected the rate of these changes, which was dependent on the meat matrix.     

偏最小二乘近红外光谱法测定瘦肉脂肪酸组成的研究

利用偏最小二乘将瘦肉的近红外光谱数据分别与其棕榈酸、棕榈油酸、硬脂酸、油酸、亚油酸含量建立校正模型,并用交互校验和外部检验来考查模型的可靠性.各脂肪酸模型的校正相关系数分别为0.9998、0.9844、0.9963、0.9754、0.9969,均方估计残差(RMSEC)分别为0.0231、0.0485、0.111、0.373、0.311,交互校验均方残差(RMSECV)分别为0.509、0.115、0.225、0.848、0.649.应用所建立的各脂肪酸近红外模型对瘦肉脂肪酸组成进行预测,并对各脂肪酸的预测值与气相色谱法测定值进行配对t-检验,结果表明两者差异均不显著(p>0.05).     

The Petroleum Industry Surfactants Synthesized from Fish Oils

Biodegradable surfactants for the petroleum industry have been synthesized by the sulfurization of fish oils. A qualitative composition analysis of surfactants was conducted by FTIR spectroscopy that showed the presence of sulfonic acid groups in the samples. Previously, several samples of the technical fish oils (fish processing waste) have been studied with regard to their use for the synthesis of biodegradable surfactants. It has been shown by gas–liquid chromatography, FTIR spectroscopy, high-performance liquid chromatography, and mass spectrometry method that samples under study contain a large amount of saturated and nonsaturated fatty acids with hydrocarbon radicals comprising from 16 to 22 carbon atoms. The results reveal that the concentration of oleic acid approaches to 15 wt%. Fish oils with a high content of free fatty acids were used as the basis for the synthesis of technical, environmentally friendly surfactants that can be applied in the petroleum industry.     

Rapid determination of C12-C26 non-derivatized fatty acids in human serum by fast gas chromatography

The concentration of long-chain fatty acids (LCFAs) in human serum is closely related to human health. It is therefore important to develop a fast, low-cost, efficient method for their determination. In this study, by using fast temperature programming and micro-bore short capillary columns, a fast gas chromatography method was developed for the direct analysis of non-derivatized LCFAs including n-dodecanoic acid to n-hexacosanic acid (C12:0-C26:0, even numbers only), linoleic acid (C18:2), oleic acid (C18:1), and erucic acid (C22:1) within 4.0 min. Method optimization including extraction and separation conditions is considered, and the analysis of real serum samples is presented. The results show that ten LCFAs were well separated with sufficient resolution, and the detection limit was in the range of 2.8-9.6 microg/mL. The reproducibility (RSD) for both intra-day and inter-day determination was always less than 15%, and the recoveries for these LCFAs were from 63.1 to 97.0%.     

Regiospecific characterisation of the triacylglycerols in animal fats using high performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry

High performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry (HPLC-APCI MS) was applied to the characterisation of triacylglycerols (TAGs) in animal fats. The major TAGs in four fats (beef, chicken, lamb and pork) were identified and positional isomers assigned according to their APCI mass spectra. Beef and lamb fat TAGs were confirmed as containing higher proportions of saturated fatty acids compared with those of chicken and pork. HPLC-APCI MS was also shown to be of value in providing regiospecific information for the fatty acids in individual TAG species. For example, beef and lamb fat were shown to contain both cis- and trans-isomers of the 18:1 fatty acid, whilst chicken and pork contained only the cis-isomer. When the position of fatty acid substitution was determined from the APCI spectra, whilst the cis- 18:1 was predominantly found in the 2-position of the TAG, the trans-18:1 showed a preference for the 1/3-position. Similarly, it was confirmed that although the 2-position of beef, chicken and lamb fat TAGs was dominated by unsaturated fatty acids, in pork fat, a characteristically high proportion of palmitic acid was seen in this position. The TAGs identified compared well with those reported previously. The distributions of 2-position fatty acids seen in lamb and pork fat compared favourably with those obtained by the more traditional method of lipase degradation. Although the distributions for chicken and beef showed some discrepancies, these can be attributed to weaknesses in the quantification procedure or the specificity of the lipase. Overall, the technique of HPLC-APCI MS has been shown to be very powerful for the regiospecific analysis of animal fats.     

高效液相色谱法测定猪油甘油三酯中的脂肪酸位置分布

 建立了一种采用高效液相色谱法(HPLC)分析猪油甘油三酯中的脂肪酸组成及其位置分布的方法。利用sn-1,3位专一性脂肪酶对甘油三酯sn-1,3位上的脂肪酸进行水解,形成sn-2位甘油单酯和游离脂肪酸；之后,通过甘油三酯中脂肪酸总含量和sn-1,3位上脂肪酸含量之间的差值计算出sn-2位上的脂肪酸含量。利用2-溴苯乙酮仅同游离脂肪酸作用的特点,将脂肪酸酯化为苯乙酰甲酯,然后进行HPLC分析。分析所用色谱柱为ZORBAX SB C18柱,以十七酸作为内标，甲醇-乙腈-水为流动相,采用梯度洗脱(梯度洗脱程序为甲醇-乙腈-水由80∶10∶10（体积比，下同）在35 min内线性变化到86∶10∶4,然后在5　min内恢复到起始比例，流动相流速为1 mL/min),通过测定苯乙酰甲酯在254 nm处的吸光度值来测定脂肪酸含量。结果表明,猪油甘油三酯中的脂肪酸主要是棕榈酸和油酸(分别占总量的26.61%和43.18%),其中油酸主要分布于sn-1,3位上,而棕榈酸分布于sn-2位上。这些测定结果与传统气相色谱法的测定结果相吻合。该方法简单可行,省去了传统测定中费时的薄层色谱分离步骤,可成为一种有效的实验室分析方法。     

杨桃状ZnO纳米片微球的制备及气敏性能的研究

以六水合硝酸锌和尿素为原料,水为反应介质,油酸作为表面活性剂,经水热过程合成了由纳米片组装的碱式碳酸锌微球前驱体,经煅烧后得到形貌一致的氧化锌(ZnO)纳米片组装的杨桃状微球。采用X射线衍射仪(XRD)和环境扫描电镜(SEM)对样品进行表征,结果表明产物为六方纤维矿结构的ZnO,微球尺寸比较均一,直径约为20μm,组装单元扇形ZnO纳米片均匀排列,单元之间存在均匀空隙,BET测试显示纳米片呈现多级介孔结孔结构,比表面积为18.9m2·g-1,室温下的光致发光性能表明其结构表面存在大量氧空位,对产物ZnO气敏元件进行了乙醇和丙酮气体敏感性测试。     

平头pH电极-流动注射联用技术快速滴定食醋中醋酸的方法研究

采用一种具有平头结构的pH电极作为流动注射分析(FIA)的检测器,构建了流动注射自动化酸度滴定系统.优化了样品进样量、流速、载液浓度和反应管长度等参数.用NaOH溶液作为载液,在4.639×10-4～0.212 mol·L-1范围内醋酸浓度的对数与FIA峰的峰面积成正比,该方法的相对标准偏差(RSD)小于0.5%.采用...     

FIA is already a routine tool in Brazil

The ability of FIA to handle large numbers of routine assays has been amply demonstrated in a laboratory in Brazil, where it is now used for 30% of the samples analysed.     

脂肪酸在超临界甲醇中的酯化反应研究

超临界甲醇中的酯化和酯交换反应是利用植物油、动物油或废油脂制备生物柴油的新工艺.它的最大特点是不需要添加催化剂,超临界甲醇既是反应媒介,又是反应物.     

在线热辅助甲基化-气相色谱法分析棉籽仁中的脂肪酸组成

建立了分析棉籽仁中脂肪酸组成的在线热辅助甲基化-气相色谱法。将0.3 mg棉籽仁样品与2 μ L三甲基氢氧化硫（0.2 mol/L）加入裂解器,在350℃下进行甲基化反应,通过气相色谱仪进行分离分析,共检测到8种脂肪酸甲酯成分,分别为亚油酸（C18：2）、油酸（C18：1）、棕榈酸（C16：0）、硬脂酸（C18：0）、肉豆蔻酸（C14：0）、棕榈油酸（C16：1）、花生酸（C20：0）和二十二酸（C22：0）,不饱和脂肪酸的相对含量为66.30%~72.54%,其中亚油酸的相对含量为43.20%~53.61%,相对峰面积的相对标准偏差（RSD）小于10%（n=5）。通过分析5组棉籽仁样品与3种食用油中的脂肪酸组成,结果表明不同产地的棉籽仁中的脂肪酸组成差异不明显,且棉籽仁中的脂肪酸组成与玉米油最为接近,相似度为0.960~0.992。该方法简单、快速、准确,适合分析棉籽仁中的脂肪酸组成。     

Analysis of fatty acids in mouse cells using reversed-phase high-performance liquid chromatography

Summary A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed to analyze various fatty acids in recombinant mouse L cells. These fatty acids were the metabolites of oleic acid. A process was developed to extract fatty acids from the cell samples before RP-HPLC analysis. The samples were first saponified with 0.5 M NaOH in 96% ethanol then extracted with acidified ethyl acetate. After extraction, the sample was dried and dissolved in HPLC-grade methanol. After centrifugation to remove insoluble impurities, the sample was applied to a C₁₈RP-HPLC column using a gradient of acetonitrile (ACN)-H₂O. The eluted fatty acids were monitored by ultraviolet (UV) absorption at 195 nm and identified by retention time and adsorption spectrum comparison. This method successfully resolved various fatty acids and provided a tool for the elucidation of the fatty acid metabolic pathway in the cells.     

Rapid Analysis of Fatty Acid Composition in Polysorbate 80 by Gas Chromatography with On-line Pyrolytic Methylation Technique

A novel method of on-line pyrolytic methylation–gas chromatography was developed for the rapid analysis of fatty acid composition in Polysorbate 80 without any tedious pre-treatment steps. Fatty acids in Polysorbate 80 were converted into their corresponding fatty acid methyl esters in the presence of trimethylsulfonium hydroxide with a vertical microfurnace pyrolyzer at 300 °C. The premixing procedure of sample and organic alkali reagent was necessary before the on-line pyrolytic methylation to improve the repeatability. The relative standard deviations for peak areas of fatty acids in Polysorbate 80 were over the range of 0.3–9.1% (n = 5). Six Polysorbate 80 samples, consisting of three samples of pharmaceutical grade and three samples of non-pharmaceutical grade, were analyzed to evaluate the feasibility of the proposed method. The relative percentages (%) of fatty acids for samples of pharmaceutical grade meet the Chinese Pharmacopoeia requirements with the amount of oleic acid varying from 78.4 to 89.3%. On the other hand, the relative percentages (%) for palmitic acid and stearic acid in samples of non-pharmaceutical grade were out of the specification limits, with the amount of oleic acid varying from 62.0 to 63.5%. The quantitative results determined by on-line pyrolytic methylation were in agreement with those obtained by off-line methylation. The result proved that gas chromatography with on-line pyrolytic methylation technique is of great value for rapid screening analysis of Polysorbate 80 samples in bulks.     

Selectively increasing of polyunsaturated (18:2) and monounsaturated (18:1) fatty acids in Jatropha curcas seed oil by crystallization using D-optimal design

ABSTRACT: BACKGROUND: This study was done to obtain concentrated polyunsaturated fatty acid (PUFA) linoleic acid (LA; 18:2) and monounsaturated fatty acid (MUFA) oleic acid (OA; 18:1) from Jatropha curcas seed oil by urea complexation. Urea complexation is a method used by researchers to separate fatty acids (FAs) based on their molecular structure. Effects the ratio of urea-to-FAs, crystallization temperature and crystallization time on the final products of urea complexation were examined. D-optimal Design was employed to study the significance of these factors and the optimum conditions for the technique were predicted and verified. RESULTS: Optimum conditions of the experiment to obtain maximum concentration of LA were predicted at urea-to-FAs ratio (w/w) of 5:1, crystallization temperature of 10 C and 24 h of crystallization time. Under these conditions, the final non-urea complex fraction (NUCF) was predicted to contain 92.81% of LA with the NUCF yield of 7.8%. The highest percentage of OA (56.14%) was observed for samples treated with 3:1 urea-to-FAs ratio (w/w) at 10 C for 16 h. The lowest percentage of LA (8.84%) was incorporated into urea complex fraction (UCF) with 1:1 urea-to-FAs ratio (w/w) at 10 C for 8 h. CONCLUSIONS: The separation of PUFA (LA) and MUFA (OA) described here. Experimental variables should be carefully controlled in order to recover a maximum content of PUFA and MUFA of interest with reasonable yield% with a desirable purity of fatty acid of interest.     

Direct analysis of fatty acid profile from milk by thermochemolysis-gas chromatography-mass spectrometry

The fatty acid composition of milk is of considerable interest due to their nutritional and functional properties. Although rapid milk fat separation and transesterification procedures have been developed, the overall procedure remains time consuming, specially, for the analysis of a large number of samples. In this work, a fast and simple method for direct profiling of fatty acids from milk using thermochemolysis has been developed. This method has the capability of directly analyse fatty acids from one drop of milk without fat extraction or cleanup. Our approach for thermochemolysis is based on thermal desorption integrated with a cold trap inlet. The optimized method does not present isomerisation/degradation of polyunsaturated fatty acid and shows milk fatty acid profiles comparable to the conventional method based on fat extraction and alkaline transesterification. Overall, this method has demonstrated significant potential for high throughput analysis of fatty acids in milk.     

Comparative quantitative fatty acid analysis of triacylglycerols using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and gas chromatography.

Quantitative analyses of fatty acids from five triacylglycerol products, coconut oil, palm kernel oil, palm oil, lard and cocoa butter, were carried out using two analytical methods: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and gas chromatography (GC), in an effort to validate the application of MALDI-TOFMS in quantitative fatty acid analysis. For the GC analysis, transmethylated products were used, whereas, for the MALDI-TOF analysis, saponified products were used. Under MALDI-TOF conditions, the acids were detected as sodiated sodium carboxylates [RCOONa + Na](+) consistent with the mode of ionization that was previously reported. Thus, the MALDI-TOF mass spectrum of saponified coconut oil showed the presence of sodiated sodium salts of caprylic acid (7.5 +/- 0.67, m/z 189), capric acid (6.9 +/- 0.83, m/z 217), lauric acid (47.8 +/- 0.67, m/z 245), myristic acid (20.4 +/- 0.51, m/z 273), palmitic acid (9.8 +/- 0.47, m/z 301), linoleic acid (0.9 +/- 0.07, m/z 325), oleic acid (4.8 +/- 0.42, m/z 327) and stearic acid (2.0 +/- 0.13, m/z 329). Saponified palm kernel oil had a fatty acid profile that included caprylic acid (3.5 +/- 0.59), capric acid (4.7 +/- 0.82), lauric acid (58.6 +/- 2.3), myristic acid (20.9 +/- 1.5), palmitic acid (7.2 +/- 1.1), oleic acid (3.8 +/- 0.62) and stearic acid (1.2 +/- 0.15). Saponified palm oil gave myristic acid (0.83 +/- 0.18), palmitic acid (55.8 +/- 1.7), linoleic acid (4.2 +/- 0.51), oleic acid (34.5 +/- 1.5), stearic acid (3.8 +/- 0.26) and arachidic acid (0.80 +/- 0.22). Saponified lard showed the presence of myristic acid (1.5 +/- 0.24), palmitic acid (28.9 +/- 1.3), linoleic acid (13.7 +/- 0.67), oleic acid (38.7 +/- 1.4), stearic acid (12.8 +/- 0.64) and arachidic acid (2.4 +/- 0.35). Finally, for saponified cocoa butter, the fatty acid distribution was: palmitic acid (32.3 +/- 1.0), linoleic acid (2.6 +/- 0.35), oleic acid (34.9 +/- 1.7) and stearic acid (30.3 +/- 1.6). Quantitative gas chromatographic analysis of the corresponding methyl esters from these triacylglycerol products yielded data that were mostly in agreement with the MALDI-TOFMS data. The MALDI-TOF experiment, however, proved to be superior to the GC experiment, particularly with regard to baseline resolution of unsaturated acids. Furthermore, the ability of MALDI-TOFMS to detect low concentrations of fatty acids rendered it more sensitive than the GC methodology.     

Multiresidue determination of pesticides in agricultural products by gas chromatography/mass spectrometry with large volume injection

A method is described for the rapid determination of pesticide residues in agricultural products. Pesticides were extracted from samples with acetonitrile. To remove pigments and fatty acids, an aliquot of the extract was cleaned up by a minicolumn that was packed both with graphitized carbon black and primary secondary amine. Analysis was performed by gas chromatography/ mass spectrometry with programmable temperature vaporizer-based large volume injection using a liner packed with phenylmethylsilicone chemically bonded silica. The method was evaluated for 114 pesticides by spiking into tomato, spinach, Japanese pear, grape, and brown rice at various concentrations of each pesticide (0.02-0.4 microg/g). The method, which gave good recovery (>60%) for 108 pesticides, is characterized by high cleanup efficiency and short cleanup time, and is useful as a rapid screening analysis.     

高效液相色谱-串联质谱法测定多种农产品中杀草强的残留量

建立了采用高效液相色谱-串联质谱法(HPLC-MS/MS)检测多种农产品中杀草强残留量的方法。根据样品基质不同,分别采用25%丙酮水溶液(针对小麦、鱼、肉和肝脏样品)、1%乙酸酸化的25%丙酮水溶液(针对玉米和花生样品)、1%乙酸水溶液(针对金银花、姜粉、花椒粉和茶叶样品)及1%乙酸水溶液和二氯甲烷(针对苹果、菠萝、菠菜、胡萝卜和紫苏叶）进行提取,然后依次采用二氯甲烷萃取、PCX或ENVI-Carb固相萃取柱净化后,进行HPLC-MS/MS测定,外标法定量。在0.005～0.1 mg/kg范围内,杀草强的峰面积与其质量浓度有良好的线性关系,相关系数为0.9997。对上述15种不同种类的农产品进行添加回收,回收率为67.5%~98.1%,相对标准偏差为1.0%~9.8%。苹果、菠菜、紫苏叶、玉米、姜、鱼和肉等样品的定量限为0.01 mg/kg,茶叶、金银花、花椒粉的定量限为0.02 mg/kg。该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求。     

Wettability of calcite and mica modified by different long-chain fatty acids (C18 acids)

The effect of long-chain fatty acid adsorption on the wetting states of calcite and mica powders is investigated. The selected long-chain fatty acids are saturated or unsaturated aliphatic acids (stearic acid and oleic acid, respectively) and naphthenic acids with saturated or unsaturated aromatic rings (18-cyclohexyloctadecanoic acid and 18-phenoloctadecanoic acid, respectively). The amount of irreversibly adsorbed acid is determined by thermogravimetric analysis. The affinity of water and n-decane for these samples before and after modification is deduced from their adsorption isotherm and microcalorimetry. Thermodynamic analysis of surface pressure and spreading tension are performed based on adsorption isotherms. The enthalpy versus coverage curve for water adsorption and its comparison to liquefaction enthalpy is shown to be a meaningful method for characterizing the wettability of a surface. The naphthenic acid with unsaturated aromatic ring deeply modifies the calcite to an oil-wet state. The mica powder was not as strongly modified as calcite by these acid molecules.