反式脂肪酸的危害及其测定方法

在不饱和脂肪酸中,会因为双键位置不同而产生几何异构体。反式脂肪酸主要来源于氢化油脂。摄入反式脂肪酸能升高血清总胆固醇和LDL-C水平,降低HDL-C水平,可能导致心血管疾病。另外,摄入反式脂肪酸也能引起必需脂肪酸缺乏,糖尿病,影响新生儿生长发育。因此,需要通过改善人们的饮食结构、减少油脂氢化、精炼过程中反式脂肪酸的产生等措施来降低反式脂肪酸对人体健康的不利影响。本文以反式油酸为例,介绍了反式脂肪酸的性质、危害、测定方法。     

油中反式脂肪酸含量与地沟油检测方法初探

对市场上6种食用油的反式脂肪酸含量进行了测定。检测结果,6种食用油总反式脂肪酸的平均含量为:橄榄油(0.19%)、茶籽油(1.01%)、花生油(1.09%)、葵花籽油(1.23%)、大豆油(1.32%),玉米油(2.04%)。用本方法测定劣质油中的反式脂肪酸,以期探索检测地沟油的方法。     

气相色谱法测定食品油脂中的十八碳反式脂肪酸

反式脂肪酸是在油脂的加氢反应或高温精炼过程中伴随产生的一类不饱和脂肪酸,过多的食用这些成分可能会对人体健康产生危害。食品油脂中以十八碳反式脂肪酸最为常见。采用气相色谱法对食品中十八碳反式脂肪酸的检测进行了实验摸索,获得了一套准确度高、精确度好的方法,可应用于日常监督检测。     

东盟国家小食品中反式脂肪酸风险评估分析

对东盟国家小食品中反式脂肪酸的风险进行评估。方法:采用气相色谱-法质谱法检测东盟小食品中反式脂肪酸的含量,对凭祥口岸进口106份东盟小食品样品检测脂肪含量,再检测出脂肪总量的反式脂肪酸含量。小食品中脂肪含量91份样脂肪含量在10%~25%之间,102份样品反式脂肪酸含量小于0.3%(我国奶粉中的限量)。东盟国家进口小食品通过食用途径的反式脂肪酸健康风险较低,属可接受风险。     

警惕饮食中的反式脂肪酸

食品安全关系着每个消费者的健康,科学研究表明,大量食用含有反式脂肪酸的食物会严重危害人体健康,并导致多种疾病产生。本文简述了反式脂肪酸的概念、来源以及对人体的危害作用,并在反式脂肪酸的摄入方面提出了几点建议。     

渭南市3种市售奶产的反式脂肪酸含量的分析

近几年来,人们的生活越来越富裕,因此人们对于饮食安全问题也越来越关注。研究显示,反式脂肪酸是能够对人体健康造成危害的脂肪酸,人们在摄取反式脂肪酸与饱和脂肪酸(saturated fatty acids,SFA)相同量的情况下,反式脂肪酸对人体健康造成的危害远远高于饱和脂肪酸(比饱和脂肪酸高2.5-10倍)。人们在正常生活中如果摄入的反式脂肪酸量过多,其患上心血管疾病、心脏病和肥胖病的几率将大增;老年人如果在日常生活中大量地摄入反式脂肪酸,则非常容易使自己患上老年痴呆症;它也能够干扰婴儿正常的生长发育等。     

隐形杀手——反式脂肪酸的来源、危害和降低措施

反式脂肪酸(Trails fatty acids,TFA)结构式(如图1),是含有反式双键的饱和脂肪酸的总称。TFA广泛存在于人造奶油、黄油、起酥油、煎炸油等氢化油的制品中,如各种糕点、薯条、炸鸡、冰淇淋等。反式脂肪酸与顺式脂肪酸(CFA)是不饱和脂肪酸的几何异构体。前者脂肪酸在双键的异侧,后者脂肪酸在双键的同侧。天然植物油中的双键多以顺式结构存在,但其不饱和度高,抗氧化能力差,稳定性不好。于是人们将植物油脂进行氢化处理,氢化后的油脂成固态或半固态且口感好,风味独特。但在油脂氢化的过程中,部分双键发生移位,顺式脂肪酸变为反式脂肪酸。油…     

傅立叶变换红外光谱法测定食品中反式脂肪酸

建立了一种食品中反式脂肪酸含量的测定方法,以酸水解法提取食品中脂肪酸,用傅立叶变换红外光谱仪对反式脂肪酸含量进行了快速测定,回收率达到89.26%~106.51%,相对标准偏差2.29%,结果重复性好,准确可靠。     

毛叶山桐子油中脂肪酸组成分析

以毛叶山桐子毛油为原料,利用容量分析方法测定其酸值、碘值及皂化值。以甲酯化方法对山桐子油进行处理后,用GC-MS法对脂肪酸组成和相对含量进行测定,结果显示其碘值为52．15g·（100g）^-1,皂化值195．39mgKOH·g^-1,主要脂肪酸为反式-9,12-十八碳二烯酸、棕榈酸、棕榈油酸等,反式-9,12-十八碳二烯酸含量最高,达59．54％。     

油脂加氢催化剂Cu-Ni-Ru和进口催化性能比较的研究

文章在相同的氢化条件下,研究了进口催化剂9910、2021和Cu-Ni-Ru分别在160℃,180℃,200℃下的氢化性能。结果表明:三种催化剂在每一温度下对大豆油氢化的活性大小顺序为Cu-Ni-Ru>9910>2021;三种催化剂的碘值和折光指数都随温度的升高而增加。Cu-Ni-Ru、9910和2021三种催化剂均在三种温度下氢化时,C18:1(油酸)反式脂肪酸在160℃下含量最低,C18:2(亚油酸)反式脂肪酸在180℃下含量最低。说明低温有利于反式脂肪酸的降低;Cu-Ni-Ru、9910和2021在相同温度条件下氢化时,催化剂比Cu-Ni-Ru比9910和催化剂2021更能使反式脂肪酸酸含量降低,有更高的选择性。     

New phospholipid fatty acids from the marine spongeCinachyrella alloclada uliczka

The fatty acid composition of phospholipids from the Senegalese spongeCinachyrella alloclada was examined. Two new fatty acids not hitherto found in nature, namely 10,13-octadecadienoic acid and 16-tricosenoic acid, were identified. 8-Hexadecenoic, 13-nonadecenoic and 5,9,13-trimethyltretradecanoic fatty acids were also found for the first time in sponges. The latter compound (1.4% of the total fatty acid mixture), an isoprenoid fatty acid, accompanies the major fatty acid 4,8,12-trimethyltridecanoic acid (19.7%). The monomethyl branched fatty acids (22%) identified include 23-methylpentacosanoic acid (anteiso-26∶0), not previously observed in sponged. The major long-chain fatty acids encountered were the known 17-tetracosenoic 19-heptacosadienoic and 5,9,23-tricontatrienoic acid. Some sixty fatty acids were identified as methyl esters andN-acyl pyrrolidides by gas chromatography and gas chromatography/mass spectrometry.     

Fatty acid composition of French infant formulas with emphasis on the content and detailed profile oftrans fatty acids

The aim of the present study was to identify and quantitatetrans isomers of C18 fatty acids in some French infant formulas. Twenty powdered infant formulas were purchased in pharmacies and supermarkets in order to assess theirtrans mono- and poly-unsaturated fatty acids content. The fatty acid profiles were examined using methyl and isopropyl ester derivatives. The combination of gas-liquid chromatography, high-performance liquid chromatography, and silver nitrate thin-layer chromatography was needed to describe the detailed fatty acid compositions of the samples, includingtrans isomers of unsaturated C18 fatty acids. All the samples containedtrans isomers of C18∶1 acid (mean level 1.97±0.28% of total fatty acids), with vaccenic acid being generally the major isomer (15 out of 20 samples), thus indicating the origin from bovine milk. All the formulas also contained various isomers of linoleic and α-linolenic acids, but at lower levels.Trans PUFA isomers are the same as those present in deodorized oils. In conclusion, all the infant formulas analyzed in this study contained sometrans fatty acids, including isomers of essential fatty acids. This should be taken into account in the dietary intake of the newborn.     

Novel branched-chain fatty acids in certain fish oils

Methyl-branched fatty acids, which are usually minor components (≤0.1%) in fish oils, were concentrated in the non-urea-complexing fraction along with polyunsaturated fatty acids during the enrichment of omega-3 fatty acids from certain fish oils via the urea complexation process. The methyl-branched fatty acids in the omega-3 polyunsaturated fatty acid concentrates, which were prepared from three fish body oils, were characterized by gas chromatography and gas chromatography/mass spectrometry. Among the major branched-chain fatty acids expected and identified were the known isoprenoid acids—mainly 4,8,12-trimethyltridecanoic, pristanic, and phytanic—and the well-known iso and anteiso structures. Two novel phytol-derived multimethyl-branched fatty acids, 2,2,6,10,14-pentamethylpentadecanoic and 2,3,7,11,15-pentamethylhexadecanoic, were identified in redfish (Sebastes sp.) oil. These two fatty acids were absent in oils from menhaden (Brevoortia tyrannus) and Pacific salmon (mixed, but mostly from sockeye,Oncorhynchus nerka). The major branched-chain fatty acid in the salmon oil, 7-methyl-7-hexadecenoic acid, was also present to a moderate extent in menhaden oil. A novel vicinal dimethyl-branched fatty acid, 7,8-dimethyl-7-hexadecenoic was detected in all of the fish oils examined, but was most important in the salmon oil. Three monomethyl-branched fatty acids, 11-methyltetradecanoic acid, and 11- and 13-methylhexadecanoic, hitherto undescribed in fish lipids, were also detected in salmon, redfish and menhaden oils. Presented in part at the First Annual Meeting of the Amer. Oil. Chem. Soc. Canadian Section, Guelph, Ontario, Oct. 8–9, 1986.     

Lipid Composition of Garlic

Neutral, glyco- and phospholipids of garlic were resolved into their component fractions by thin layer chromatography. Neutral lipids contained considerable quantities of monoglycerides (18.5%), diglycerides (14.2%), sterols (16.3%) and triglycerides (41.5%) respectively. The phospholipid fraction was rich in phosphatidyl choline (23.5%), phosphatidyl ethanolamine (17.9%), lysophosphatidyl choline (11.8%) and lysophosphatidyl ethanolamine (8.2%). Digalactosyl diglyceride (10.1%), sterol glycoside (15.6%), cerebrosides (8.1%), acylsterol glycoside (38.6%) and monogalactosyl diglyceride (22.5%) were the major components of the glycolipids of garlic. Lauric, myristic, palmitic and linoleic acids constituted the major fatty acids of monoglycerides, diglycerides and free fatty acid fractions whereas palmitic, linoleic and linolenic acids were the major fatty acids of triglycerides. Palmitic and linoleic acids were the major fatty acids of garlic phospholipids. Except the acylsterol glycoside fraction glycolipids were rich in lauric, palmitic, linoleic and linolenic acids; palmitic acid was the only major fatty acid of acylsterol glycosides.     

Tissue distribution of phytanic acid and its analogues in a kinship with Refsum's disease

Three of six kin were identified, by high performance thin layer chromatography, capillary gas chromatography and mass spectrometry, as having phytanic acid storage disease. Phytanic acid was found in triacylglycerol and, to a lesser degree, in phosphatidylcholine and free fatty acids. An unsaturated analogue of phytanic acid was additionally identified in plasma and erythrocyte triacylglycerols. In plasma, branched chain fatty acids were primarily localized in the low density lipoprotein fraction. The concentration of plasma major fatty acids was not affected by the presence of these branched chain fatty acids. In contrast to plasma, only small amounts of phytanic acid were found in cerebrospinal fluid and biopsied sural nerve. The nerve phytanate was mainly associated with triacylglycerol in epineurial and perineurial tissues. Lack of phytanate accumulation in sural endoneurium, even in cases with severe fiber degeneration, suggests that demyelination in Refsum's disease may not be due to myelin instability resulting from the incorporation of branched chain fatty acids into peripheral nerve membrane.     

Gas-liquid chromatographic analysis of cyclopropenoid fatty acids

A method is described for the analysis of cyclopropenoid fatty acids in oils. The method consists of reacting the methyl esters of the cyclopropenoid fatty acids with silver nitrate in methanol to form ether and ketone derivatives. The derivatives formed from the cyclopropenoid fatty acids are separated from the methyl esters of the normal fatty acids by gas-liquid chromatography on a 15% diethylene glycol succinate column. The method is applicable to oils containing from 0.01% to 100% of cyclopropenoid fatty acids. The derivatives of oils containing lew levels of cyclopropenoids are separated from the normal methyl esters by alumina chromatography prior to gas-liquid chromatography. Studies on the quantitative aspects of the derivative formation, alumina chromatography, and gas-liquid chromatography are reported. Analyses for total cyclopropenoid fatty acid content of cottonseed oil andSterculia foetida oil by the gas-liquid chromatographic and hydrobromic acid titration procedures showed good agreement. Replicate analyses of a sample ofSterculia foetida oil for malvalic and sterculic acid gave coefficients of variation of 6.04% and 1.17%, respectively.     

The high content of monoene fatty acids in the lipids of some midwater fishes: Family myctophidae

The total lipids of eleven species of Myctophids caught at depths between 20 and 700 m in the northern Pacific Ocean were analyzed using silicic acid column chromatography (lipid classes) and capillary gas chromatography (fatty acid and fatty alcohol composition). The major components in the lipid classes were triacylglycerols or wax esters; triacylglycerols were the dominant acyl neutral lipids (68.1–96.1%) in eight species, and wax esters were found as the dominant lipid (85.5–87.9%) in three species. The major fatty acids and alcohols contained in the was esters of the three fishes were 18:1n–9, 20:1n–9, 20:1n–11, and 22:1n–11 for fatty acids, and 16:0, 18:1, 20:1, and 22:1 for fatty alcohols. Fatty acids in the triacylglycerols ranging from C₁₄ to C₂₂ were predominantly of even chain length. The major components were 16:0, 16:1n–7, 18:1n–9, 20:1n–11, 22:1n–11, 20:5n–3 (icosapentaenoic acid), and 22:6n–3 (docosahexaenoic acid). In both the triacylglycerols and the wax esters, the major fatty components were monoenoic acids and alcohols. It is suggested from the lipid chemistry of the Myctophids that they may prey on the same organisms as the certain pelagic fishes such as saury and herring, because the large quantities of monoenoic fatty acids are similar to those of saury, herring, and sprats whose lipids originate from their prey organisms such as zooplanktons which are rich in monoenoic wax esters.     

Fat-Soluble Bioactives,Fatty Acid Profile and Radical Scavenging Activity of <Emphasis Type="Italic">Semecarpus anacardium</Emphasis> Seed Oil

Semecarpus anacardium (family Anacardiaceae) has many applications in the Ayurvedic and Siddha systems of medicine in India. Detailed knowledge on the composition of S. anacardium oil, in consideration of potential utilization, is of major importance. In this investigation, column chromatography, gas chromatography, thin layer chromatography and liquid chromatography techniques were performed to analyze lipid classes, fatty acids and fat-soluble bioactives of S. anacardium crude seed oil. The amount of neutral lipids in the crude seed oil was the highest, followed by glycolipids and phospholipids, respectively. Linoleic followed by palmitic and oleic were the major fatty acids. The ratio of unsaturated fatty acids to saturated fatty acids was higher in neutral lipid classes than in the polar lipids. The main sterol compounds were β-sitosterol, campesterol and stigmasterol. δ-Tocopherol followed by β-tocopherol were the main tocopherols. When S. anacardium seed oil and extra virgin olive oil were compared for their radical scavenging activity toward 1,1-diphenyl-2-picrylhydrazyl radical and galvinoxyl radical (by electron spin resonance spectrometry), S. anacardium seed oil exhibited a stronger RSA.     

Fatty acid composition of polar lipids in goats' milk

Silicic acid column chromatography was used to separate the polar lipids of goats' milk into glycolipid, phosphatidylethanolamine, phosphatidylserine plus phosphatidylinositol, phosphatidylcholine, and sphingomyelin fractions. Each fraction was purified by column chromatography and its fatty acid profile determined by gas liquid chromatography and mass spectrometry. The glycerophospholipids each contained 18∶1 as the predominant fatty acid (∼45%). The sphingolipids contained a high percentage of long-chain saturated fatty acids (C₂₂ to C₂₄>45%); the glycolipid fraction also contained ca. 2% 2-hydroxy fatty acids. The data represent a comprehensive cross-sectional study of the major polar lipids found in goats' milks.     

Fatty acid composition of carotenoid esters in soybean and rapeseed oils

The amounts of the different carotenoids (lutein, lutein monoesters and diesters) in soybean and rapeseed oil were determined through a combination of column chromatography and UV spectrometry. The lutein diesters in the oils have been isolated by a combination of column and thin layer chromatography. Identification and determination of the amount of the various fatty acids of the lutein diesters have been carried out by means of gas chromatography after transesterification of the fatty acids to their methyl esters. Comparison of the fatty acids of the lutein diesters with those of the triglycerides of the oils revealed a striking difference. First, the fatty acids of the lutein diesters have shorter chains than the triglycerides acids. Secondly, the lutein fatty acids are more saturated than the fatty acids of the triglycerides of the corresponding oils. However the amount of linoleic acid in the case of the fatty acids of the lutein diesters in rapeseed oil is greater than that in the fatty acids of the triglycerides in rapeseed oil. Deceased, October 26, 1971.