食品及油脂中反式脂肪酸含量定性定量分析方法

目的:采用气相色谱法定性定量分析食品及油脂中反式脂肪酸含量。方法:食品中提取的脂肪或油脂样品直接甲酯化,于SP-2560(100 m×0.25 mm×0.2μm)弹性石英毛细管柱上进行分离,并经FID检测器检测。通过标准品保留时间、脂肪酸甲酯的链等长值定性(ECL)及顺反式脂肪酸甲酯出峰规律进行定性,面积归一化法定量计算反式脂肪酸在油脂中的百分含量。结果:该方法可使顺反式脂肪酸甲酯得到有效分离,从而进行准确定量。结论:此方法具有简单、快速、准确的特点,适用于食品营养标签的测定。     

德阳市市售食品中反式脂肪酸含量的调查及检测方法的改进

目的 对食品中反式脂肪酸的检测方法进行改进,以便了解德阳市市售食品中反式脂肪酸的含量,为进一步评估反式脂肪酸对德阳市市民健康的影响提供依据。方法 采用分层随机抽样的方法采集德阳市市售烘焙食品、巧克力及糖类、膨化食品、含油小吃、肉及肉制品和奶及奶制品等6类食品共112份样品,采用柱前衍生-气相色谱法对样品中的反式脂肪酸含量进行检测。结果 各种脂肪酸甲酯出峰良好,检出限为0.0065～0.0069 g/100 g,回收率为78.24%～90.10%,相对标准偏差（RSD%）为4.13%;反式脂肪酸含量最高的为烘焙食品（1.407 g/100 g）,其次为肉及肉制品（1.341 g/100 g）、巧克力及糖类（1.269 g/100 g）,最后是含油小吃（0.932 g/100 g）、膨化食品（0.691 g/100 g）和奶及奶制品（0.445 g/100 g）。结论 该方法缩短了检测时间,能够很好地完成食品中反式脂肪酸含量的检测。反式脂肪酸在食品中普遍存在,德阳市居民每日从食物中摄入的反式脂肪酸含量远低于WHO的建议限值（1%）。     

动植物油脂中反式脂肪酸测定方法的建立

目的建立适合国内条件的动植物油脂中反式脂肪酸测定方法,为国标方法提供依据。方法选择普通植物油、动物油和氢化植物油三个大类共9种动植物油脂样品,参照国际标准经部分修改,建立了适合国内条件的反式脂肪酸气相色谱分析及用面积归一法定量的测定方法,并进行了重复性测定和实验室间的验证。结果在实验条件下,油脂中脂肪酸可以得到很好的分离;除个别含量极低的脂肪酸外,各脂肪酸组分10次分析结果的相对标准偏差均小于10%,其中反式脂肪酸总和的RSD值在豆油和氢化豆油中分别是2.0%和0.3%;实验室间验证结果也表明,该方法在不同实验室间的结果有很好的一致性,豆油、氢化豆油、猪油三种样品的反式脂肪酸总和的RSD值分别是5.0%、1.1%和4.6%,均远小于10%。结论该检测方法实验室内和实验室间的精密度均较高,且所需仪器比较普及,操作步骤简单易行,分析时间短,适合国内开展,可作为我国动植物油脂反式脂肪酸的测定方法之一。     

反式脂肪酸——安全问题与管理现状

反式脂肪酸是含有反式双键的不饱和脂肪酸，容易在油脂的加工和精炼过程中产生。近年来大量文献报道了反式脂肪酸对人体的不利作用，国际组织及各国纷纷采取相关措施，降低或限制油脂中反式脂肪酸含量。本文就目前文献中关于反式脂肪酸的产生、安全问题、各国的管理现状进行综述，以期为我国该方面的研究提供参考。     

甲酯化-气相色谱法检测食品中反式脂肪酸

目的：建立检测食品中反式脂肪酸含量的方法，应对国外食品营养标签的新变化。方法：用乙醚提取食品中脂肪，经甲酯化反应后，采用100m长CP-Sil88 FAME毛细管柱、程序升温、FID检测器的气相色谱仪检测。结果：顺、反式脂肪酸的分离良好；检出限为9μg／ml，线性r值为0．998，相对标准偏差（RSD）为0．73％-1．73％，加标回收率为97．4％-101．2％。结论：本法准确、可靠、简捷，可作为检测食品中反式脂肪酸含量的推广方法。     

食品中反式脂肪酸危害及检测方法研究进展

反式脂肪酸定义为化学结构包含一个或多个非共轭的双键的构型为反式的脂肪酸，它包括单不饱和反式脂肪酸和多不饱和反式脂肪酸。反式脂肪酸（TFAS）是普通植物油经过人为改造变成“氢化油”过程中的产物。丹麦政府依据该国营养委员会对反式脂肪酸潜在危害性的研究结论，于2003年6月制定了严格的规定，成为世界上第一个对食品中反式脂肪酸设立法规进行限制的国家。     

德阳市市售植物油中反式脂肪酸含量调查

目的 了解德阳市市售植物油中反式脂肪酸的含量范围。方法 利用分层随机抽样抽取12类德阳市市售植物油共计121份样品,应用气相色谱法对样品中反式脂肪酸进行分离检测,采用归一化法进行结果计算。结果 德阳市市售植物油中12种反式脂肪酸的含量范围为未检出至3.19%,以反式亚麻酸（C18:3T）为主,其中橄榄油未检测出反式脂肪酸,最常见的菜籽油、玉米油、调和油、大豆油的反式脂肪酸平均含量分别为1.64%、2.20%、1.75%、2.58%。结论 德阳市市售植物油中普遍存在反式脂肪酸且含量各不相同。     

齐齐哈尔市售乳制品中反式脂肪酸的测定

目的了解市售乳制品中是否存在反式脂肪酸,并测定其存在的种类和含量。方法随机抽取市售的奶粉、纯牛奶和酸奶3种奶制品,采用气相色谱法外标法定量,分别对3种乳制品中反式脂肪酸组成进行测定。结果硬脂酸甲酯(C18∶0)、顺式油酸甲酯(C18∶1-9c)与反式油酸甲酯(C18∶1-9t),顺式亚油酸甲酯(C18∶2-9c,12c)与反式亚油酸甲酯(C18∶2-9t,12t)分离效果良好。3种乳制品中反式脂肪酸均有检出,反式脂肪酸含量为0.129~0.216 g/100 g。结论市售的奶粉和纯牛奶样品检出1种反式脂肪酸,酸奶样品检出2种反式脂肪酸。     

致病元凶:反式脂肪酸

反式脂肪酸一词近来引起了广大消费者的关注。要科学看待反式脂肪酸,既不能草木皆兵,也不能掉以轻心。什么是反式脂肪酸反式脂肪酸也称反式脂肪,它分为两类:天然的和人工制造的。前者是牛羊肉和牛羊奶中的反式脂肪,含量不高,对人体没有危害;后者是在油脂加工和烹调过程中产生的,过量食用会     

谈谈反式脂肪酸

<正>反式脂肪酸也叫人造脂肪,是将植物油中的不饱和脂肪酸经过催化、加氢,使不饱和脂肪酸的结构发生变化,变成反式脂肪酸。氢化后的植物油不仅不易氧化酸败,能延长食品的保质期,     

Determination of trans fatty acid levels by FTIR in processed foods in Australia

Health authorities around the world advise 'limiting consumption of trans fatty acid', however in Australia the trans fatty acid (TFA) content is not required to be listed in the nutrition information panel unless a declaration or nutrient claim is made about fatty acids or cholesterol. Since there is limited knowledge about trans fatty acid levels in processed foods available in Australia, this study aimed to determine the levels of TFA in selected food items known to be sources of TFA from previously published studies. Food items (n=92) that contain vegetable oil and a total fat content greater than 5% were included. This criterion was used in conjunction with a review of similar studies where food items were found to contain high levels of trans fatty acids. Lipids were extracted using solvents. Gravimetric methods were used to determine total fat content and trans fatty acid levels were quantified by Attenuated Total Reflectance Fourier Transform Infrared spectroscopy. High levels of trans fatty acids were found in certain items in the Australian food supply, with a high degree of variability. Of the samples analysed, 13 contained greater than 1 g of trans fatty acids per serving size, the highest value was 8.1 g/serving. Apart from when the nutrition information panel states that the content is less than a designated low level, food labels sold in Australia do not indicate trans fatty acid levels. We suggested that health authorities seek ways to assist consumers to limit their intakes of trans fatty acids.     

Fat in the diets of adolescent girls with emphasis on isomeric fatty acids

To determine the amount of isomeric fatty acids in the diets of a segment of the American population, daily food intake was collected, using the duplicate portion method, from eight healthy white adolescent girls for 7 days. The fifty-six diets were analyzed for fatty acids by gas-liquid chromatography. The amount of trans isomers of octadecenoic acid (18:1t) in the diets of the eight girls ranged from 3.5 to 8.2% of total fatty acids with an average of 5.3%. Other trans fatty acids included trans isomers of 14:1 and 16:1, and cis,trans and trans,cis isomers of 18:2. No measurable amounts of trans,trans octadecadienoic acid (18:2tt) were found in the diets of the girls. The total trans fatty acid content of the diets averaged 6.5% of total fatty acids. The daily consumption of total trans fatty acids by the eight girls over a 1 wk period averaged 3.1 g, with 2.6 g of this being 18:1t.     

Formation of trans fatty acids in chicken legs during frying

The formation of trans fatty acids in chicken legs during frying in unhydrogenated and hydrogenated soybean oil was studied. Frying was conducted at 160°C, 180°C and 200°C for 15, 30, 45, 60 and 75 min, with the various cis and trans fatty acids being analyzed in unhydrogenated and hydrogenated soybean oil, as well as chicken leg meat and chicken leg skin, using a gas chromatography–mass spectrometry technique. Results showed that the amounts of most fatty acids decreased along with increasing frying temperature and frying time when fried in unhydrogenated or hydrogenated soybean oil. No trans fatty acids were formed in chicken leg meat fried in unhydrogenated or hydrogenated soybean oil. Instead, the formation of trans fatty acids was observed in chicken leg skin fried in hydrogenated soybean oil, probably because of oil absorption. A maximum level of trans fatty acids occurred 15 min after frying and then declined thereafter.     

Formation of trans fatty acids in chicken legs during frying

The formation of trans fatty acids in chicken legs during frying in unhydrogenated and hydrogenated soybean oil was studied. Frying was conducted at 160 degrees C, 180 degrees C and 200 degrees C for 15, 30, 45, 60 and 75 min, with the various cis and trans fatty acids being analyzed in unhydrogenated and hydrogenated soybean oil, as well as chicken leg meat and chicken leg skin, using a gas chromatography-mass spectrometry technique. Results showed that the amounts of most fatty acids decreased along with increasing frying temperature and frying time when fried in unhydrogenated or hydrogenated soybean oil. No trans fatty acids were formed in chicken leg meat fried in unhydrogenated or hydrogenated soybean oil. Instead, the formation of trans fatty acids was observed in chicken leg skin fried in hydrogenated soybean oil, probably because of oil absorption. A maximum level of trans fatty acids occurred 15 min after frying and then declined thereafter.     

Intensification of essential fatty acid deficiency in the rat by dietary trans fatty acids

Two studies were conducted using male rats to assess the effect of trans fatty acids upon essential fatty acid (EFA) deficiency. In the first study 5% corn oil (CO), hydrogenated coconut oil (HCNO) or margarine stock (MS, partially hydrogenated soybean oil) were fed, and the levels of trans fatty acids in tissue lipids were measured. The trans fatty acids present in MS were found to intensify EFA deficiency and to be retained in tissue lipids to a high degree, especially in heart phospholipids (PL). In the second study, as the level of trans fatty acids increased in the diet, increasingly higher levels of trans fatty acids were deposited in the heart PL. As dietary trans acid increased, a decrease in total omega 6 fatty acids, and a decrease in the sum of 18:2 omega 6 + 20:4 omega 6 - 20:3 omega 9 fatty acids in heart PL occurred, both criteria indicating a shift toward an increasing EFA deficiency state. Studies of delta 5 desaturase activity of liver microsomes in selected groups showed an increase in the conversion of 20:3 omega 6 to 20:4 omega 6 as the trans fatty acid level in the diet increased.     

中国市售桶装植物油脂肪酸的研究

目的对市售桶装植物油中脂肪酸进行分析,探讨其组分及含量特点。通过植物油中各类脂肪酸比例的特点,分析脂肪酸特征。方法从北京、云南、浙江、湖南、河南、哈尔滨、江苏、甘肃8个地区,选取市场普遍销售的或各地自产的品牌桶装植物油,共计8个品种,每个样品采集2个不同批号。对植物油脂进行皂化和甲酯化后,利用岛津GC2014气相色谱仪对样品进行气相色谱分析。结果市售桶装植物油主要以棕榈酸、油酸、亚油酸和α-亚麻酸为主,反式脂肪酸的平均含量为1.05g/100g。植物油的饱和脂肪酸∶单不饱和脂肪酸∶多不饱和脂肪酸的比值范围为1∶1.6～9.4∶0.9～7.4;多不饱和脂肪酸中n-6/n-3的比值范围为0.37～289.5∶1。结论市售桶装植物油反式脂肪酸含量低,但脂肪酸组成比例大多不符合中国营养学会提出的标准,并且多数缺乏n-3多不饱和脂肪酸。     

Variability in the trans fatty acid content of foods within a food category: implications for estimation of dietary trans fatty acid intakes.

OBJECTIVE: Currently, the published information on trans fatty acid composition of foods is incomplete and of questionable accuracy. Detailed fatty acid analysis of over 200 foods was undertaken for the purpose of determining the variability in trans fatty acid content among foods within a product category, and the significance of this variability to the estimation of trans fatty acids intakes from analysis of dietary intake data. METHODS: The analysis of food fatty acids used gas-liquid chromatography with 100 m capillary columns and standardized methodologies for food sampling, fat extraction, separation and quantification of trans fatty acid isomers. For the purposes of this report, trans refers to all non-naturally occurring isomers including trans, cis-trans, geometric and positional isomers. RESULTS: The results show that the amount of trans fatty acids varies considerably among foods within a category, reflecting differences in the fats and oils used in the manufacturing or preparation process. For example, the range of trans fatty acids in 17 brands of crackers was 23 to 51% total fatty acids, representing differences of from 1 to 13 g trans fatty acids per 100 g cracker. The large errors that may arise in estimates of the trans fatty acid intake of an individual are illustrated by analyses of the potential trans fatty acid intake in a sample diet, for each food as calculated using the minimum and maximum values for trans fatty acids within a given category. The results of these analyses show estimates of trans fatty acid intake from a low of 1.4 to 25.4 g a day for the same diet. CONCLUSION: This study shows that the wide variability in trans fatty acid content of different foods may result in large errors in the estimation of trans fatty acid intake of individuals and, potentially, groups.