傅里叶变换红外光谱法对掺假橄榄油的快速鉴别

利用衰减全反射傅里叶红外光谱法对掺假橄榄油进行了快速鉴别研究。对掺入转基因大豆油、非转基因大豆油、花生油、玉米油、葵花籽油、调和油等的橄榄油采用160℃高温加热8h处理,通过观察样品加热前、后二阶导数光谱在988cm-1处特征吸收峰的吸光度变化,准确鉴别橄榄油是否掺假。该方法操作简便、前处理无需有机试剂,可作为市场筛查掺假橄榄油的快速鉴别方法。     

二阶导数紫外吸收光谱测定复合氨基酸注射液中的色氨酸和苯丙氨酸的含量

复合氨基酸注射液是含有11种氨基酸及甘露醇的复方制剂。文献曾报导用二阶导数光谱测定蛋白质及天然物中的色氨酸;徐绪温等使用双波长分光光度计,用导数光谱法测定了复合氨基酸注射液中色氨酸,本文提出用二阶导数光谱直接测定色氨酸和苯丙氨酸含量的方法。实验方法 (一)仪器与试剂所用仪器为岛津UV-240型自记式紫外分光光度计OP1-1附件。氨基酸标准物均为广州侨光制药厂提供的日本进口试剂,按药典检定合格;甘露醇,分析纯。复合氨基酸注射液由广州侨光制药厂提供,为内含11种氨基酸及甘露醇的无菌水溶液,     

氮化硅ν_(Si-N)伸缩振动的衰减全反射红外光谱研究

采用变温傅里叶变换衰减全反射红外光谱法(ATR-FTIR),在313~393K温度范围内,分别研究了α-氮化硅和β-氮化硅分子结构的红外一维光谱、红外二阶导数光谱和红外四阶导数光谱,并针对氮化硅Si-N伸缩振动,利用二维相关红外光谱考察了温度变化对氮化硅分子结构的影响。结果表明:在波数950~850cm~(-1)范围内,氮化硅主要存在着Si-N伸缩振动模式(νSi-N)。随着测定温度的升高,α-氮化硅νSi-N红外吸收强度的变化顺序为874cm~(-1)886cm~(-1)880cm~(-1),而β-氮化硅νSi-N红外吸收强度的变化顺序为876cm~(-1)880cm~(-1)890cm~(-1)。     

SPME/GC-MS鉴别地沟油新方法

采用固相微萃取(SPME)气相色谱-质谱联用(GC-MS)技术,研究了油脂内源及外源物质的微量化学成分。结果发现:纯正花生油和大豆油不含反式脂肪酸,地沟油含有反式脂肪酸trans-C18∶1、trans-C18∶2;纯正花生油和大豆油中含有正己醛、正壬醛和正癸醛等杂质,而地沟油中除了这几种醛类外还含有乙酸、3-丁烯腈、2,5-二甲基吡嗪等特征杂质成分。通过测定内源性物质和外源性物质的存在,两种检测结果互相印证,综合判断,最终可确定是否为地沟油,据此首次建立了SPME/GC-MS鉴别地沟油的新方法。该方法不但可用于地沟油的鉴别,还可用于掺假食用油的检测。     

傅里叶变换红外光谱结合模式识别法快速鉴别食用油的真伪

采用傅里叶变换红外光谱(FTIR)结合簇类独立软模式识别技术(SIMCA)建立了真伪食用油的快速鉴别方法. 该方法依据FTIR 的指纹特性, 收集并分析了53 个合格食用油和13 个伪造食用油的FTIR 谱图; 通过对谱图取二阶导数和标准化处理, 主成分分析(PCA)提取特征变量; 采用SIMCA 方法分别随机选取43 个合格食用油和9 个伪食用油样品的FTIR 谱图组成训练集, 构建得到真伪食用油的SIMCA 分类模型. 该模型经过剩余10 个合格食用油和4 个伪食用油的验证, 正确识别率达到了100%. 说明FTIR 结合SIMCA 可能成为快速鉴别食用油真伪的一种新方法.     

GC-MS法鉴别食用油和餐饮业中废弃油脂的研究

用气相色谱 质谱联用(GC MS)方法对7种餐饮业中废弃油脂(简称废油脂)和5种合格成品食用油(简称食用油)中所有脂肪酸进行分析。研究发现,废油脂中部分不饱和脂肪酸受到氧化,使脂肪酸相对不饱和度(U R)值明显小于同种类食用油中的脂肪酸相对不饱和度(U R)值,其脂肪酸的质量分数分布与同种类的食用油中脂肪酸的质量分数分布有很大的区别,以及绝大部分废油脂中存在较大量矿物油。研究表明,脂肪酸相对不饱和度(U R)值和脂肪酸的质量分数分布可以鉴别废油脂。     

气相色谱法分析食用油中脂肪酸含量的一种改进的衍生化方法

食用油加四甲基氢氧化铵醇溶液，在室温中用碘甲烷将其转变为对应的甲酯。使用Ｓｕｐｅｒｏｘ－４弹性石英毛细管柱对各种脂肪酸甲酯进行分离分析。考察了不同反应时间和不同量甲基化试剂对甲酯化完全程序的影响，并用此法测定了豆油，菜油，小麻油，色拉油和煎炒色拉油后回收油的脂肪酸成分及含量。     

紫外导数光谱法应用于人血清白蛋白含量测定及不同白蛋白的鉴别

目前各国药典对人血清白蛋白注射液均有记载,其含量测定采用经典的半微量凯氏定氮法测定蛋白总量,以电泳法作纯度试验,未提出鉴别不同白蛋白的方法。近十年来,Matsushima等和Fell曾报导用导数光谱测定和鉴别蛋白质及天然物中的芳香氨基酸。本文提出用二阶导数光谱对人血清白蛋白进行含量测定和一阶导数光谱进行鉴别的方法,目前尚未见有关报导。本法简便、快速、专属性强,含量测定结果与半微量凯氏定氮法比较基本一致。     

精炼对萝卜籽油理化指标及脂肪酸组成的影响

采用超临界CO2萃取和正己烷提取的萝卜籽毛油为原料,依次按照水化脱胶、碱炼脱酸、吸附脱色和真空加热脱臭的工序对毛油进行精炼,并考察了各精炼阶段油脂的理化指标及脂肪酸组成变化情况。结果表明,各精炼阶段对萝卜籽油的相对密度、折光指数、碘值和皂化值没有显著影响,磷脂含量、酸值、过氧化值和色泽则变化显著。萝卜籽油脂肪酸组成与菜籽油相似,各精炼阶段组成均有变化,但是变化幅度都比较小,油脂中不饱和脂肪酸含量有所降低。精炼萝卜籽油清澈透明,酸值、过氧化值、水分及挥发物含量等指标均达到国家二级食用油的标准,其中油脂中的不饱和脂肪酸含量可达到85%,单不饱和脂肪酸含量可达到64%。     

顺磁共振和傅里叶变换红外光谱法研究高温对荒漠苔藓质膜结构影响

运用顺磁共振波谱和原位傅立叶变换显微红外光谱研究了高温对荒漠植物刺叶墙藓不同叶龄水合组织质膜透性和膜蛋白二级结构的影响。自旋标记法研究质膜透性结果表明,处理前野生叶质膜透性普遍高于室内培养获得的原丝体和次生叶,处理后次生叶膜透性变化最大,比处理前增加4倍,其次为原丝体。质膜透性随叶龄增加,变化幅度逐渐降低。红外光谱的二阶求导、傅立叶自解卷积及拟合分峰等结果显示,各叶龄间蛋白质二级结构含量差异较大,表明各龄组织蛋白成分不完全相同;高温处理后次生叶和原丝体α螺旋含量分别比对照增加40%和16%;其它叶龄组织二级结构含量变化范围小,表明热胁迫下老龄组织蛋白质二级结构稳定。膜透性和膜蛋白二级结构分析证明,膜透性和蛋白质稳定性呈正相关,指示蛋白质组成和含量不同是造成各龄组织不同耐热性的主要原因之一。     

Trans polyunsaturated fatty acid contents in Brazilian refined soybean oil.

This study examined the concentration (mg/g) of trans polyunsaturated fatty acid (TPFA) in five soybean oil brands by gas-liquid chromatography. Tricosanoic acid methyl ester was used as the internal standard. All samples analyzed presented trans 18:2 fatty and trans 18:3 acids in detectable amounts. The concentration of TPFA ranged from 5.8 to 30.2 mg/g, with a mean concentration value of 18.4 mg/g. Trans 18:3 fatty acids had the highest TPFA group concentrations, which ranged from 3.9 to 16.3 mg/g. The main isomer of this group presented the 9c, 12c, 15t configuration. For trans 18:2 fatty acids, concentrations ranged from 1.9 to 14.0 mg/g with a mean value of 8.1 mg/g. Alpha-linolenic acid (all cis) concentrations ranged from 30.7 to 60.6 mg/g and their degree of isomerization ranged from 6.0 to 31.5, indicating that the deodorization process varies from one producer to another. From per capita consumption of soybean oil brands in Brazil and their TPFA concentrations, it is possible to conclude that their contribution to the average TPFA intake per person in Brazil is 0.4 g/d.     

Overview of infrared methodologies for trans fat determination

trans Fatty acids are present in a variety of foods like dairy products, but the major sources are products that contain commercially hydrogenated fats. Some studies have shown that trans fatty acids elevate levels of serum low-density lipoprotein (LDL)-cholesterol and lower high-density lipoprotein (HDL)-cholesterol. The quantitation and identification of trans fatty acid isomers is difficult because of the wide range of positional monoene, diene, and triene fatty acid isomers present in hydrogenated oils. This is complicated by the cis positional isomers that are also present, as well as the lack of commercial chromatographic standards for many fatty acid isomers. In this review, infrared methodologies for the determination of total trans fat are presented. Using an attenuated total reflection (ATR) infrared cell, a novel Fourier transform infrared (FTIR) spectroscopic method that was developed for the rapid (5 min) quantitation of the total trans fatty acid levels in neat (without solvent) fats and oils measured as triacylglycerols (TAG) is discussed. TAG required no derivatization, but had to be melted prior to measurement. The lower limit of trans quantitation was 5% of total fat. The precision of this ATR method was found to be superior to that of transmission infrared official methods. Accuracy was enhanced by generating a symmetric absorption trans infrared band at 966 cm(-1) on a horizontal background. This was achieved by "ratioing" the single-beam spectrum of the trans-containing fat or oil against that of a reference oil or standard having only cis double bonds. Attempts to apply this ATR-FTIR method to food matrixes with low trans fat and/or low total fat content were not satisfactory due to interfering infrared absorptions in the trans region. To overcome this interference, the method was modified by applying the standard addition technique to the ATR-FTIR determination. The modified procedure required more time, but eliminated any adverse impact on accuracy arising from interfering minor food components having absorption bands near 966 cm(-1).     

Determination of trans octadecenoic acids by silver-ion chromatography-gas liquid chromatography: an intercomparison of methods

Several silver-ion chromatography-gas liquid chromatography (GLC) techniques for the determination of trans octadecenoic acids in partially hydrogenated vegetable fats were collaboratively evaluated. Twelve laboratories participated in the study. All collaborators used high polarity fused silica capillary columns for the separation of fatty acid methyl esters by GLC; 7 collaborators isolated trans monoenes by silver-ion liquid chromatography (Ag-LC) and the remainder used silver-ion thin-layer chromatography (Ag-TLC). Eight artificially prepared materials [soybean oil spiked with either methyl elaidate, trielaidin, or trans octadecenoates isolated from partially hydrogenated sunflower oil (PHSO)] and 2 matrix materials (PHSO and a blend of PHSO and palm oil) served as test samples. Ag-TLC and Ag-LC proved to be equivalent techniques for the prefractionation of trans monoenes. Recovery of methyl elaidate, trielaidin, or trans octadecenoates isolated from PHSO varied between 97.9-103.7% over a concentration range of 1 to 30 g trans fatty acids/100 g. Reproducibility relative standard deviation (RSDR) for the spiked samples were in the range of 3.1-8.6% for 30-1% trans monoene content. For the 2 matrix samples (mean 3.75 and 19.08% trans monoene content) RSDR was 13.2 and 3.6%. The hyphenated techniques tested proved to be highly accurate and sufficiently precise methods for the determination of trans monoenes in partially hydrogenated vegetable fats. Procedural variations of the silver-ion chromatography prefractionation step (separation mode, mobile phase, and detection systems) did not significantly influence the results of the test. Therefore, silver-ion chromatography is a robust method, which does not need rigorous standardization to achieve high precision of test results. A further benefit of the hyphenated technique is that any type of efficient polar capillary column can be used.     

内标法测定甘油酯上的十一烷酸和13-甲基十四烷酸及其在非正常油脂掺伪识别中的应用

结合非正常油脂(地沟油)的来源(加热植物油和动物油)及反映其不同来源的重要特征指示物,即连接在甘油酯上的十一烷酸和13-甲基十四烷酸,建立了内标法测定油脂中甘油酯上十一烷酸和13-甲基十四烷酸的方法。多维气相色谱-质谱采用不分流进样和选择性切割可以实现在线净化和富集,提高分析的灵敏度和分离度。十一烷酸和13-甲基十四烷酸的方法检出限分别达到0.070、0.006 mg/kg。此外,研究发现绝大多数正常植物油中十一烷酸和13-甲基十四烷酸的含量比非正常油脂中二者的含量低。通过待测油脂中十一烷酸和13-甲基十四烷酸的含量可以在一定程度上推断食用植物油的品质。     

In Vitro and In Vivo Digestibility of Soybean,Fish, and Microalgal Oils,and Their Influences on Fatty Acid Distribution in Tissue Lipid of Mice

The digestion rates of microalgal (docosahexaenoic acid, DHA, 56.8%; palmitic acid, 22.4%), fish (DHA, 10.8%; eicosapentaenoic acid, EPA, 16.2%), and soybean oils (oleic, 21.7%; linoleic acid, 54.6%) were compared by coupling the in vitro multi-step and in vivo apparent digestion models using mice. The in vitro digestion rate estimated based on the released free fatty acids content was remarkably higher in soybean and fish oils than in microalgal oil in 30 min; however, microalgal and fish oils had similar digestion rates at longer digestion. The in vivo digestibility of microalgal oil (91.49%) was lower than those of soybean (96.50%) and fish oils (96.99%). Among the constituent fatty acids of the diet oils, docosapentaenoic acid (DPA) exhibited the highest digestibility, followed by EPA, DHA, palmitoleic, oleic, palmitic, and stearic acid, demonstrating increased digestibility with reduced chain length and increased unsaturation degree of fatty acid. The diet oils affected the deposition of fatty acids in mouse tissues, and DHA concentrations were high in epididymal fat, liver, and brain of mice fed microalgal oil. In the present study, microalgal oil showed lower in vitro and in vivo digestibility, despite adequate DHA incorporation into major mouse organs, such as the brain and liver.     

葵子油脂肪酸2-氨基-2-甲基-丙醇化学修饰气相色谱-质谱分析

以2-氨基-2-甲基-丙醇为脂肪酸的化学修饰试剂,气相色谱一电子轰击质谱（GC-EI MS）分析葵子油脂肪酸。2-氨基-2-甲基-丙醇将脂肪酸羧基修改为含氮杂环,使在EI源中避免了链烯基中碳碳双键的移动。解析了葵子油脂肪酸2-氨基-2-甲基-丙醇化学修饰产物的EI质谱图,讨沦了烯酸中碳碳双键的定位规则,确定了葵子油脂肪酸中碳碳双键的位置。鉴定出葵子油6种脂肪酸,不饱和脂肪酸相对含量为89．41％,其中人体必需脂肪酸9,12-十八碳二烯酸含量占65．30％。本方法为不饱和脂肪酸中双键的定位提供了新的技术手段。     

超高效合相色谱-质谱法快速分析食用植物油中常见脂肪酸

建立了超高效合相色谱-质谱(UPC²-MS)快速分析6种食用植物油(玉米油、葵花籽油、大豆油、茶油、菜籽油、花生油)中棕榈酸、硬脂酸、油酸、亚油酸、亚麻酸等5种常见脂肪酸的方法,并比较了这6种食用油中上述5种脂肪酸的含量差异。采用皂化反应对植物油进行前处理,以ACQUITY UPC² BEH 2-EP色谱柱(100 mm×2.1 mm, 1.7 μm)为分析柱,以超临界CO₂-甲醇/乙腈(1:1, v/v)为流动相进行梯度洗脱,流速为0.8 mL/min。在电喷雾负离子模式下进行检测,外标法定量。结果表明:5种脂肪酸标准物质在0.5~100 mg/L范围内呈现良好的线性关系,相关系数为0.9985~0.9998,定量限(S/N≥10)为0.15~0.50 mg/L;在3个添加水平下,样品的加标回收率为89.61%~108.50%;方法重复性的相对标准偏差(RSD)为0.69%~3.01%。该方法简单、快速、分离效果好,无需对脂肪酸样品进行衍生化,已成功地用于玉米油、葵花籽油、橄榄油、茶油、大豆油和花生油等6种食用油中常见脂肪酸含量的测定。     

Production of Human Milk Fat Replacement Rich of 1,3-dioleoyl-2-palmitoilglycerol From Enzymatic Interesterification Tripalmitin,Ethyl Oleate And Mixture of VCO,Soybean Oil And Fish Oil

Human Milk is naturally the only source of food for infant in their early life. It contains 2-6% lipid which provides about 50% of the total energy needed by the infant. Human milk fat (HMF) mainly as TAG with the specific fatty acid composition, palmitic acid (C16:0) (20-25%), which is primary located at sn-2 of glycerol bonds (70%) and oleic acid (C18:1), located at sn-1,3 (35%). HMF also provide fatty acids such as linoleic acid, linolenic acid, EPA, DHA and lauric acid that are very important for infant. The purposes of this research are to synthesize of 1,3-dioleoyl-2-palmitoilglycerol (OPO) and to determine the best composition of OPO, VCO, soybean oil and fish oil for HMFS production for infant formula. Interesterification of tripalmitin and ethyl oleate using immobilized lipase from Rhizomucor miehei (Lipozym RM IM) were used to synthesize of OPO. Interesterification product of mixed VCO, soybean oil and fish oil that are source of lauric acid, linoleic acid, α-linolenic, EPA and DHA, were formulated in mass ratio (58:20:20:2) and (70:18:10:2) for obtaining HMFS which have fatty acids composition similar or close to HMF. Composition of fatty acids from product were analyzed by GCMS. From this research, were obtained HMFS containing palmitic acid as much as 28.89% where 84.49% of that are located at sn-2 while sn-1,3 position are dominated by oleic acid as much as 55.11% from the total 38.7% and 70:18:10:2 w/w is the best composition of interesterification product, VCO, soybean oil and fish oil to obtain HMFS similar to HMF.     

Physicochemical characteristics of the Lasiococca comberi Haines seeds

Physicochemical characteristics and fatty acid composition of Lasiococca comberi Haines (Euphorbiaceae), an endangered forest tree species, were determined for the first time. The oil, protein, crude fibre and carbohydrate contents in seeds were 41.5, 13.8, 22.2 and 11.6%, respectively. The refractive index, pH, specific gravity, saponification value, iodine value, peroxide value and p-anisidine value of seed oil were 1.4781, 6.4, 0.9, 178.4 mg KOH/g, 196 g I₂/100 g of oil, 5.1 mEq O₂/kg and 188.4, respectively. The predominant fatty acids were linolenic acid (65.3%), oleic acid (13.8%), linoleic acid (7.1%) and palmitic acid (5.3%). HPLC analysis revealed the presence of α-tocopherol (13.2 mg/100 g) and γ-tocopherol (6.3 mg/100 g) as the major tocopherols. The results indicated that L. comberi seed oil can be classified as drying oil having possible applications in different industries and as an important dietary source of omega-3 fatty acids.     

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.