A simple method for regiospecific analysis of triacylglycerols by gas chromatography

A simple method for regiospecific analysis of triglycerides was developed. It consists of partial deacylation of triglycerides by ethylmagnesium bromide followed by derivatization of monoglycerides with n-butyryl chloride, and direct analysis of dibutyrate derivatives of monoglycerides by gas chromatography. The chromatographic conditions were carried out with monoglycerides of C₁₂ to C₂₀ fatty acids and resulted in separation of dibutyrate derivatives between those bearing the medium- or long-chain fatty acid in the sn-1(3) and sn-2 positions of glycerol. Beef tallow and grapeseed and cotton seed oils were analyzed using this new method, and their regiospecific distributions were compared with literature data. The method does not require separation of products by thin-layer chromatography or special analytical equipment other than a standard gas chromatograph, and it can thus be used for routine regiospecific analysis of triglycerides.     

Ester alkoxylation technology

Conventional ethyoxylation technologies, when used on fatty methyl esters, produce poor yields as well as flat ethoxymer distributions. Peaking ethoxylation catalysts have been successful in efficient conversion of methyl esters into the ethoxylates possessing peaked ethoxymer distribution. Surfactant performance of methyl ester ethoxylates was evaluated. Results generally show these to behave similarly to alcohol ethoxylates, with the exception of exhibiting a lower foam profile. This ester ethoxylation technology has been successful in ethoxylating esters of varying steric environments. Triglyceride ethoxylates have been partially saponified as well as glucaminolyzed to produce mild surfactant blends. Samuel Rosen Memorial Award Presentation, at the 90^th American Oil Chemists' Society Annual Meeting and Expo, Orlando, FL, May 1999. The author dedicates this paper to the memory of the late Professor William H. Wade of the University of Texas, Austin, TX.     

Effects and molecular mechanisms of Ninghong black tea extract in nonalcoholic fatty liver disease of rats

The aim of this study is to observe the effects of Ninghong black tea extract on fat deposition and high-fat diet-induced nonalcoholic fatty liver disease (NAFLD) and to explore the potential mechanisms of these effect. Under 2% Ninghong black tea extract diet feeding in rat model, the results showed that Ninghong black tea extract decreased the body fat ratio and the number of lipid droplets in the liver and significantly alleviated NAFLD in the rat model. The real-time fluorescence quantitative polymerase chain reaction results showed that Ninghong black tea extract significantly upregulated the expression of peroxisome proliferator-activated receptor α (PPARα), which is important in fatty acid β-oxidation, and microsomal triglyceride transfer protein (MTP), which plays an important role in the synthesis of very low density lipoprotein (VLDL). By promoting the expression of PPARα and MTP in liver tissue and thereby promoting fatty acid β-oxidation and VLDL synthesis, Ninghong black tea extract relieves high-fat diet-induced NAFLD.     

Lipase-catalyzed synthesis of chiral triglycerides

Under certain reaction conditions, the acidolysis of tripalmitin with oleic acid using immobilized lipase from Rhizomucor miehei resulted in a higher level of monosubstituted oleoyldipalmitoyl (OPP) triglycerides than had been predicted according to kinetic modeling. The reaction products were subjected to chiral analysis by high-performance liquid chromatography (HPLC), which indicated that the enzyme was more active at the sn-1 position of the triglyceride than at the sn-3 position, resulting in synthesis of the chiral triglyceride 1-oleoyl-2,3-dipalmitoyl-sn-glycerol. A kinetic model was developed and was correlated with the HPLC method to provide a simple means to predict the stereoselectivity of lipase-catalyzed reactions. By using the model, the stereoselectivity of immobilized Rhizomucor miehei lipase was found to depend strongly on the initial water activity (a _w) of the reaction mixture, with greater selectivity occurring at lower a _w. The sn-1 selectivity was essentially maintained using various solvents, or without solvent, when a _w was kept constantly low. Variation in the fatty acid composition of the triglyceride indicated that shorter-chain fatty acids result in greater stereoselectivity, while variation of the chainlength of the free fatty acid indicated an enhancement by the longest chainlength. The stereoselectivity of this lipase was confirmed using a new ¹³C nuclear magnetic resonance method. By using immobilized R. miehei lipase at low a _w approximately 80% of the chiral triglyceride found in the reaction mixture was the sn-1 enantiomer, at high reaction conversion.     

高效液相色谱-蒸发光散射法分析动物油脂种属特征

目的分析确定5种动物油脂的甘油三酯种属特征。方法采集5种常见动物油脂(猪、牛、羊、鸡、鸭),用丙酮提取后直接进样分析,采用高效液相色谱-蒸发光散射法(high performance liquid chromatographyevaporative light scattering method,HPLC-ELSD),色谱柱为C18柱,流动相为二氯甲烷-乙腈-冰乙酸(30:70:0.2,V/V/V),流速1.0 mL/min,柱温35℃,蒸发光散射检测器检测。结果在本文所优化的动物油脂高效液相色谱-蒸发光散射分析条件下,10种甘油三酯组分都能够得到有效分离,5种动物油脂的谱图数据特征性强,且有自己的特征峰,同种属动物油脂谱图相似性高。结论甘油三酯可以作为鉴定这5种动物油脂种属的依据,为市场打假及清真食品检验提供参考方法。     

Possibility of improving the quality characteristics of olive‐pomace oil and enhancing its differentiation from refined olive‐pomace oil

An investigation was carried out to evaluate the oxidative and hydrolytic degradation of 37 olive‐pomace oils marketed in southern Italy and to compare the results with those obtained from 10 deodorised olive‐pomace oils representative of large stocks of oil obtained after the final step of refining. One aim of the research was to ascertain the quality characteristics of commercial olive‐pomace oils; another was to verify whether the legally prescribed addition of virgin olive oil to refined pomace oil, so that the final product may be classified commercially as olive‐pomace oil, was actually sufficient to justify upgrading. The analytical methods used were silica gel column chromatography and high‐performance size exclusion chromatography. The data obtained showed that the final retail olive‐pomace oils had a lower degree of oxidative degradation than the refined oils, as indicated by the lower values obtained when summing the proportions of triglyceride oligopolymers and oxidised triglycerides. Conversely, hydrolytic degradation, which was evaluated by determining diglycerides, proved to be the same in the two categories of oil. The proportions of virgin olive oil added are small, as indicated by the statistically indistinguishable values of triglyceride oligopolymers and free fatty acids obtained. The possibility of setting a limit to the amount of triglyceride oligopolymers present in the commercial category of olive‐pomace oil has been considered. This limit would ensure standardisation of the level of oxidation and, consequently, of the quality of marketed oils and would enhance differentiation between olive‐pomace oil and refined olive‐pomace oil. © 2000 Society of Chemical Industry     

中碳链脂肪酸甘油三酯的研究进展

中碳链脂肪酸甘油三酯作为一种高效消化吸收的结构脂质和控制脂肪吸收的低能油脂,不仅能够控制肥胖和降低血清胆固醇,还能够抑制或限制组织中的胆固醇沉积物.与普通植物油脂相比,中碳链脂肪酸甘油三酯独特的理化性质和代谢途径使其具有特殊的营养价值、药用价值和生理功能.本文对中碳链脂肪酸甘油三酯的理化性质、制备、代谢特征和生理功能等方面进行简要的概述,以期为中碳链脂肪酸甘油三酯在食品、医药和日用化工等领域的应用提供有益参考.     

樟树籽仁油醇解工艺研究

以樟树籽仁油为原料,研究在合成中碳链甘油三酯过程中醇解的工艺条件,主要对樟树籽仁油醇解工艺参数,如醇油摩尔比、反应温度、反应时间、催化剂的用量等作了探讨,并从理论上加以分析,用正交法确定了醇解的最佳工艺参数,为樟树籽仁油生产中碳链甘油三酯提供关键技术.     

焙炒处理对不同植物油品质特性的影响北大核心CSCD

为了研究焙炒对植物油品质的影响,以油菜籽、亚麻籽、花生、葵花籽和芝麻为原料,经焙炒处理后采用液压压榨法制油(热榨油),分析植物油的理化指标(酸值、过氧化值、水分及挥发物、色泽)、主体组分(脂肪酸组成及含量、甘三酯组成及含量、挥发性组分)和总酚含量,并与未焙炒处理直接压榨制取的油(冷榨油)作对比。结果表明:热榨油酸值和过氧化值显著高于冷榨油(p<0.05),其中,热榨亚麻籽油酸值(KOH)最高(0.96 mg/g),热榨菜籽油过氧化值最高(1.02 mmol/kg);冷榨油水分及挥发物含量显著高于热榨油(p<0.05),其中冷榨花生油水分及挥发物含量最高(0.16%);热榨油的色泽较冷榨油深,其中热榨菜籽油的色泽最深(R1.1,Y31);焙炒对植物油脂肪酸和甘三酯组成及含量无显著影响(p>0.05);热榨油中醇类、醛类和酸类等挥发性组分较少,但杂环类物质较多;热榨菜籽油、亚麻籽油、花生油、葵花籽油和芝麻油总酚含量分别是其冷榨油的1.38、1.57、1.51、1.80倍和1.27倍。因此,焙炒对植物油品质影响较大,应根据生产需要选择合适的预处理方式。     

液-质联机分析氧化鸡脂中极性非（难）挥发性组分

采用固相萃取/反相高效液相色谱-大气压化学电离质谱(RP-HPLC-APCI MS)、反相高效液相色谱-电喷雾电离质谱(RP-HPLC-ESI MS),分析了脂肪调控氧化工艺制备的氧化鸡脂的极性非(难)挥发性物质组成。鉴定出甘三酯的双氢过氧化物、单氢过氧化物、单环氧化物及甘二酯等4类共35种化合物,其中单氢过氧化物23种占绝大多数。以三亚油酸甘三酯单氢过氧化物为外标定量分析氧化鸡脂中单氢过氧化物,总含量为121.36mg/kg氧化鸡脂,其中含量最高的为亚油酸二油酸甘三酯单氢过氧化物(45.05 mg/kg)。研究表明,鸡脂调控氧化主要对鸡脂中含不饱和脂肪酸的甘三酯进行氧化,是较为温和的氧化工艺,形成的极性非(难)挥发性氧化产物主要是肉香前体——甘三酯单氢过氧化物。