Authentication analysis of cod liver oil from beef fat using fatty acid composition and FTIR spectra

This study aimed to authenticate cod liver oil (CLO) from beef fat (BF) by determining the level of BF as a fat adulterant in CLO. Two instrumental techniques, namely GC-FID for fatty acid analysis and Fourier transform infrared (FTIR) spectroscopy, were exploited for such authentication. The decreased level of some fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), could be used as an indicative means to detect the adulteration of CLO with BF. In addition, FTIR spectroscopy combined with partial least-squares (PLS) at frequency regions of 1200-1000 cm(-1) was successfully developed for the quantification of BF in CLO. Using the PLS model, the errors obtained in calibration and prediction samples were 0.55% and 0.82% v/v, respectively.     

Detection of fresh palm oil adulteration with recycled cooking oil using fatty acid composition and FTIR spectral analysis

There is a growing concern over the food safety issue related to increased incidence of cooking oil adulteration with recycled cooking oil (RCO). The objective of this study was to detect fresh palm olein (FPO) adulteration with RCO using fatty acid composition (FAC) and Fourier-transform infrared spectroscopy (FTIR) spectral analyses combined with chemometrics. RCO prepared in the laboratory was mixed with FPO in the proportion ranged from 1% to 50% (v/v) to obtain the adulterated oil samples (AO). FACs for FPO, RCO, and AO were determined using gas chromatography equipped with a flame ionization detector (GC-FID). The compositions of most fatty acids in RCO lied within the normal ranges of Codex standard, except for C8:0, C10:0, C11:0, C15:0, trans C18:1, and polyunsaturated fatty acids (PUFAs), C20:5. PUFAs showed a consistent decreasing trend with increasing magnitude of change with respect to increasing adulteration level and thus might be a good indicator for detecting FPO adulteration with RCO. The evaluation parameters (coefficient of determination, root mean standard error) of the FTIR-partial least square (PLS) model of palm oil adulteration with recycled oil are R² = 0.995 and 3.25, respectively. For FTIR spectral analysis, the distinct variations in spectral regions and aberrations in characteristic bands between FPO and RCO were observed. The optimized PLS calibration model developed from normal spectral of the combined region at 3602–3398, 3016–2642, and 1845–650 cm^?1 overpredict the adulteration level. On the other hand, the discriminant analysis classification model was able to classify the FPO and AO into two distinct groups. Improvement of the principles of combined techniques in authenticating AO from fresh oil is beneficial as a guideline to detect adulteration in cooking oil.     

基于指纹图谱和化学计量分析的鳕鱼肝油软胶囊掺假植物油鉴定

目的 建立一种基于脂肪酸气相色谱(gas chromatography, GC) 指纹图谱技术结合化学计量分析的鳕鱼肝油软胶囊中掺假植物油的鉴定方法。方法 采用GC法测定不同来源鳕鱼肝油软胶囊脂肪酸指纹图谱, 经拟合后构建对照指纹图谱, 并进行样品相似度评价。模拟制备鳕鱼肝油软胶囊中掺入不同种类、不同比例植物油的掺假样品, 以其中14个共有脂肪酸峰的相对峰面积作为数据源, 输入SIMCA-P数据分析软件进行主成分分析(principal component analysis, PCA)及掺假模型建立。结果 获得鳕鱼肝油软胶囊GC对照指纹图谱及三维掺假识别模型, 44批样品经相似度评价发现有2批拟似掺假植物油, 将拟似样品色谱数据标准化后导入SIMCA-P软件, 显示2批样品均掺了大豆油, 掺假比例约为15%和35%。结论 脂肪酸GC指纹图谱结合化学计量分析为鳕鱼肝油软胶囊中掺假植物油的鉴定提供一种可靠准确的检测手段, 可快速有效识别鳕鱼肝油掺假行为。     

W/O型牛肉肌内脂肪乳状液脂肪酸成分的研究

采用毛细管气相色谱法对大豆油、葵花籽油、橄榄油、杏仁油、核桃油和牛油及配制好的4种W/O型牛肉肌内脂肪乳状液的脂肪酸组成及含量进行分析。配制的4种W/O型牛肉肌内脂肪乳状液(BSS、BSSA、BSSW和BSSO)中的功能性多不饱和脂肪酸亚油酸、不饱和脂肪酸和必需脂肪酸含量均分别高达44%、87%和44%以上,而牛油中则仅分别为2.29%、60.91%、2.407%。说明配制的W/O型牛肉肌内脂肪乳状液达到了改善脂肪酸组成的目的,符合脂质营养新观点。将W/O型牛肉肌内脂肪乳状液注射于大理石花纹不丰富的牛肉中,可以改善牛肉脂肪酸的配比。      

山茱萸籽油提取工艺优化及脂肪酸组成分析

优选山茱萸籽油超声提取工艺条件,分析含油的脂肪酸组成。以提取时间、超声功率、提取温度、固液比为影响因素,通过均匀设计法优选山茱萸籽油的最佳提取工艺为:提取时间22min,超声功率136W,提取温度52℃,固液比1∶29,最佳得率为7.366%;通过气相色谱法从山茱萸籽油中鉴定出6种主要脂肪酸,占总脂肪酸含量的99.013%,其中亚油酸(71.190%)为山茱萸籽油的主要脂肪酸,其他依次为油酸(18.594%)、顺-10-十五碳烯酸(5.377%)、硬脂酸(2.176%)、α-亚麻酸(1.226%)、顺-11-二十碳烯酸(0.450%)。实验结果表明,山茱萸籽油富含不饱和脂肪酸,具有很高的营养价值,并且是很好的亚油酸来源。     

Authentication of Extra Virgin Olive Oil from Sesame Oil Using FTIR Spectroscopy and Gas Chromatography

The presence of sesame oil in extra virgin olive oil has been investigated using Fourier transform infrared spectroscopy and gas chromatography. Frequencies of 1207–1018, 1517–1222, and 3050–2927 cm^?1 were chosen for quantification of sesame oil in extra virgin olive oil. Using Fourier transform infrared normal spectra coupled with a partial least square model, the root mean standard error of calibration and root mean standard error of prediction obtained were relatively low, i.e., 0.331 and 1.01% (vol/vol), respectively. Using fatty acid profiles as determined by gas chromatography, the levels of palmitic and oleic acids were decreased linearly with R² of 0.969 and 0.934, meanwhile the levels of stearic and linoleic acids were increased with R² of 0.930 and 0.959, respectively, with the increasing levels of sesame oil. From level 10% sesame oil (vol/vol), all these fatty acids are significantly different (p < 0.05).     

香榧子油的理化性质及脂肪酸组成分析

主要对香榧子油的理化性质及脂肪酸组成进行了分析。结果表明,香榧子粗蛋白、粗脂肪、饼粕总糖及淀粉质量分数分别为48.3%、14.6%、37.6%和68.3%。香榧子油的酸值、碘值、过氧化值及皂化值分别为0.95 mg KOH/g、131.3 g/100 g、8.76 mmol/kg、137.9 mg KOH/g。香榧子油主要由12种脂肪酸组成,饱和脂肪酸以山嵛酸(12.2%)为主,其次是棕榈酸(9.95%)和十七碳酸(0.18%);不饱和脂肪酸中亚油酸(41.9%)和油酸(26.0%)较高,还含有3.51%的共轭二烯酸——顺-11,顺-13-二十碳二烯酸;长碳链脂肪酸质量分数较高,达18%。香榧子油Sn-2位脂肪酸主要由油酸(46.5%)和亚油酸(45.3%)组成。香榧子油甘三酯组成中分布比较均匀,主要为β-LOL(7.51%)、LLL(7.32%)、β-LOBe(6.28%)和β-LLBe(6.12%)。     

基于脂肪酸指标的调和植物油品质评析

目的 对比基于脂肪酸指标的调和植物油与纯种植物油的品质.方法 利用气相色谱归一法测定2类植物油中8个样品的脂肪酸组成,建立相应的指标,对比分析其品质.结果 以脂肪酸种类为评定指标,调和植物油1#、2#脂肪酸种类总数最多,无反式脂肪酸检出,含有二十二碳六烯酸组分;以饱和脂肪酸、单不饱和脂肪酸、多不饱和脂肪酸比值为评定指标...     

Improving the determination of moisture in edible oils by FTIR spectroscopy using acetonitrile extraction

A Fourier transform infrared (FTIR) method developed for the analysis of moisture in edible oils using dry acetonitrile as the extraction solvent was re-examined with the objective of improving its overall sensitivity and reproducibility. Quantitation was based on the H-O-H bending absorption at ～1630 cm(-1) instead of the bands in the OH stretching region, fewer interferences being an issue in the former as opposed to the latter region. In addition, a spectroscopic dilution correction procedure was developed to compensate for any miscibility of oil samples with acetonitrile, and gap-segment 2nd derivative spectra were employed to minimise the associated possibility of spectral interferences from absorptions of the oils. In comprehensive standard addition experiments using a variety of edible oils, the FTIR method was shown to recover the amounts of water quantitatively added to dry oil with an accuracy of ±20 ppm when the spectra of the acetonitrile extracts of the water-spiked oils were ratioed against the spectra of the acetonitrile extracts of the corresponding dry oils. The accuracy deteriorated substantially when the spectra of the acetonitrile extracts of the water-spiked oils were ratioed against the spectrum of the acetonitrile extraction solvent only. However, the primary variable affecting the apparent difference in the accuracy of the two approaches was determined to be the variability in the residual moisture content of the dried oils used in the standard addition experiments, as confirmed by an FTIR procedure based on H-D exchange with D(2)O. The FTIR method as structured is amenable to automation (>120 samples/h) and provides a very competitive means by which to routinely measure moisture present in a variety of hydrophobic materials that are normally the domain of Karl Fischer titration, such as edible oils, mineral oils, biodiesel and fuels.     

The polyunsaturated fatty acid composition of beef and lamb liver

The effect on liver fatty acids of two typical beef production systems, steers fed grass (grazing) and bulls fed concentrates, was investigated. Liver fatty acids were also studied in lambs grazing grass. Total fatty acid content of liver in the beef animals was not affected by production system, being 3.5% for grass and 3.7% for concentrates although carcasses of the latter animals were leaner. The percentages of the major non polyunsaturated fatty acids (PUFA) were also similar: (concentrates in parentheses) 18:0, 25.2% (25.1%); 16:0, 13.3% (14.5%); 18:1 12.6% (14.0%). Total liver PUFA contents were similar for the two production systems and much higher than in muscle from the same animals. All n-3 PUFA were present in greater amounts in liver from grass fed animals and n-6 PUFA were higher in concentrate fed animals: mg/100g liver, 18:3n-3 92 (32); 20:5 n-3, 151 (17); 22:5 n-3, 283 (108); 22:6 n-3, 83 (32); 18:2 n-6, 172 (444); 20:4 n-6, 194 (270). The P:S ratios were 0.20 (grass) and 0.32 (concentrates) and the n-6:n-3 ratios were 0.71 and 4.8, respectively. Livers from grass-fed lamb had a higher fat content, 4.9%, than the beef livers and a lower percentage of 18:0, (21%); but more 16:0, (16%) and 18:1 (21 %). Total PUFA content of lamb's liver resembled that of beef liver and the composition was similar to that of the steers fed grass. However the concentrations of 18:3 n-3 and 22:6 n-3 were higher in lamb and contributed to a lower n-6: n-3 ratio of 0.46 although the P:S ratio of 0.18 was similar to that in beef liver. Ruminant liver is potentially a good source of C20 and C22 PUFA in the human diet particularly from grass fed animals, with a highly desirable n-6:n-3 ratio and this may be more important nutritionally than the low P:S ratio since people can offset this elsewhere in the diet.     

云南省不同引种地油橄榄果制取的油脂脂肪酸组成和角鲨烯含量分析

为了对云南省引种油橄榄优异种质资源提供理论依据,收集云南省不同引种地不同品种的油橄榄果,用索氏法提取橄榄油,通过气相色谱法测定其脂肪酸组成及角鲨烯含量。结果表明：不同引种地同一品种的橄榄油脂肪酸组成具有一定的相似性,大多聚于一类;不同品种橄榄油具有不同的脂肪酸组成,同一品种不同成熟度油橄榄果制取的橄榄油脂肪酸组成差异不大;不同品种橄榄油中角鲨烯含量变化幅度较大,最低值与最高值之间相差8.2 mg/g。综上,同一品种橄榄油的脂肪酸组成总体上具有一定的遗传稳定性,不同品种橄榄油具有不同的脂肪酸组成,且角鲨烯含量差异显著。     

Variation in oil content and fatty acid composition of the seed oil of Acacia species collected from the northwest zone of India

BACKGROUND: The oil content and fatty acid composition of the mature seeds of Acacia species collected from natural habitat of the northwest zone of the Indian subcontinent (Rajasthan) were analyzed in order to determine their potential for human or animal consumption. RESULTS: Oil content varied between 40 and 102 g kg^?1. The highest oil content was obtained in Acacia bivenosa DC. (102 g kg^?1) among the nine Acacia species. The fatty acid composition showed higher levels of unsaturated fatty acids, especially linoleic acid (～757.7 g kg^?1 in A. bivenosa), oleic acid (～525.0 g kg^?1 in A. nubica) and dominant saturated fatty acids were found to be 192.5 g kg^?1 palmitic acid and 275.6 g kg^?1 stearic acid in A. leucophloea and A. nubica respectively. Seed oils of Acacia species can thus be classified in the linoleic–oleic acid group. Significant variations were observed in oil content and fatty acid composition of Acacia species. CONCLUSION: The present study revealed that the seed oil of Acacia species could be a new source of high linoleic–oleic acid‐rich edible oil and its full potential should be exploited. The use of oil from Acacia seed is of potential economic benefit to the poor native population of the areas where it is cultivated. The fatty acid composition of Acacia seed oils is very similar to that reported for commercially available edible vegetable oils like soybean, mustard, sunflower, groundnut and olive. Hence the seed oil of Acacia species could be a new source of edible vegetable oil after toxicological studies. Copyright © 2012 Society of Chemical Industry     

桃仁油的超声波辅助提取及脂肪酸组成分析

以正己烷为溶剂,利用超声波辅助提取桃仁油,采用二次正交回归旋转组合设计,研究了提取温度、提取时间、料液比、超声波功率对出油率的影响,并通过GC-MS测定了桃仁油的脂肪酸组成。结果表明,各因素对桃仁油出油率的影响顺序为:料液比>提取温度>提取时间>超声波功率,最优提取工艺为:提取时间68min,料液比1∶10(g/mL),提取温度57℃,超声波功率160W。GC-MS结果显示桃仁油中含有8种脂肪酸,其中不饱和脂肪酸占88.48%,主要成分是油酸(57.69%)和亚油酸(30.43%)。     

多个番茄果实样品脂肪酸含量及组成比较分析

采用索氏提取法提取8个番茄果实样品中的粗脂肪,用KOH-甲醇溶液对脂肪酸进行甲酯化,以37种脂肪酸标品为对照,采用气相色谱分析法测定其脂肪酸含量及组成。结果表明:番茄果实干物质平均含量5.86%,种子含量0%～0.51%,粗脂肪平均含量6.97%;番茄果实样品间脂肪酸总量差异明显,最大可达10倍以上;番茄果实脂肪酸总量与种子量一定程度正相关;番茄果实脂肪酸相对百分含量有一定差异,其主要脂肪酸组成及含量为棕榈酸13.2%～26.4%、硬脂酸0%～6.2%、油酸0%～27.5%、亚油酸50.5%～70.9%、亚麻酸2.5%～20.0%。研究结果可为番茄育种、栽培和资源综合开发利用提供参考。      

食用油脂中特丁基对苯二酚气相色谱测定方法

建立了食用油脂中特丁基对苯二酚(TBHQ)的气相色谱测定方法.根据TBHQ溶解于乙醇的性质,利用80%乙醇溶液将油脂中TBHQ提取出来,采用气相色谱法对其进行测定.TBHQ在0～250μg/mL浓度范围内线性良好,相关系数0.9999,最低检出限为0.001g/kg,按0.05、0.10和0.20g/kg三个添加水平测定回收率在91.9%～98.0%之间, 7次重复测定的变异系数在3.9%～5.9 %之间,与液相色谱法相比较,采用F检验法对实际样品进行了检验,结果表明两方法没有显著性差异.     

Review of the use of phytosterols as a detection tool for adulteration of olive oil with hazelnut oil

Adulteration of virgin olive oil with less expensive oils such as hazelnut oil is a serious problem for quality control of olive oil. Detection of the presence of hazelnut oil in olive oil at low percentages (<20%) is limited with current official standard methods. In this review, various classes of phytosterols in these two oils are assessed as possible markers to detect adulterated olive oil. The composition of 4-desmethyl- and 4-monomethylsterols is similar in both oils, but the 4,4′-dimethylsterols differ. Lupeol and an unknown (lupane skeleton) compound from 4,4′-dimethylsterols are exclusively present in hazelnut oil and can be used as markers via GC–MS monitoring to detect adulteration at levels as low as 2%. The phytosterol classes need to be separated and enriched by a preparative method prior to analysis by GC or GC/MS; these SPE and TLC methods are also described in this review.     

菜籽油脂肪酸组成特征指标及大豆油掺伪后不合格判定的研究

对2011年至2013年全国592份油菜籽样品和我站近年来检测菜籽油的数据进行汇总分析。当菜籽油中掺入不同比列的大豆油时,采用气相色谱法与植物油油脂定性试验进行检测,比较气相色谱组分分析法与油脂定性试验的化学法的差异性,并对是否符合菜籽油脂肪酸组成进行判定。结果表明:从油菜籽提油脂肪酸组成数据分析得到:特征1:芥酸(C22∶1)与油酸(C18∶1)含量线性相关程度极高,用C22∶1对C18∶1作图得到两者线性方程Y=-1.112 02X+64.536 83,相关系数为R=-0.988 1,P0.001,有非常显著的统计学意义。特征2:92.39%菜籽油的棕榈酸(C16∶0)值不超过4.5%。特征3:99.06%正常菜籽油的亚油酸(C18∶2)范围在11.8%~20.3%。可利用这3项特征指标对菜籽油脂肪酸组成是否合格进行综合判定,较GB/T 5539—2008 4.7和GB/T 1536—2004判定方法,能有效降低掺伪检出限。     

Correlation of fatty acid composition of vegetable oils with rheological behaviour and oil uptake

The fatty acid compositions of seven edible vegetable oils were investigated and correlated with their rheological behaviours and the amount of absorbed oils to fried products. All oil samples showed constant viscosity as a function of shear rate, exhibiting Newtonian behaviours. The highest viscosity was observed in hazelnut oil, followed by olive, canola, corn, soybean, sunflower, and grapeseed oils. In addition, a high correlation (R² = 0.94) demonstrated that the flow behaviours of vegetable oils were positively governed by their major components (18:1 and 18:2 fatty acids). It was also shown that a more rapid change in viscosity with temperature was observed in the oils containing more double bonds (R² = 0.71). Furthermore, even though the overall tendency was that the potato strips fried in the oils with high viscosity appeared to cause more oil uptake, a significant effect of oil types on oil uptake was not observed.