油脂同步荧光光谱检测及橄榄油掺假鉴别

采用同步荧光光谱仪,在激发波长250~720 nm,波长间隔Δλ=15 nm时,采集20种食用植物油和掺杂的特级初榨橄榄油的荧光光谱图,分析比较了各种植物油脂的同步荧光光谱图。结果表明,同步荧光光谱法能够将特级初榨橄榄油与其他17种植物油明显地区分开来。在橄榄油掺杂鉴别中,其中14种植物油掺兑量在1%的情况下,同步荧光光谱图与特级初榨橄榄油有着明显的差异。同步荧光光谱法对橄榄油掺假鉴别,无需复杂的样品前处理,本方法简便、快速、灵敏,适合快速筛查。     

基于同步荧光光谱的杜仲籽油掺假检测研究

建立基于同步荧光光谱的杜仲籽油掺假判别分析模型及检测方法。以杜仲籽油和7种常见植物油为研究对象,采集激发波长范围为250～700 nm,波长间隔为60 nm的同步荧光光谱,分析杜仲籽油和常见食用油的荧光光谱特性,利用光谱峰面积建立掺假判别模型并对其进行验证。结果表明:杜仲籽油与其他7种植物油的荧光特性存在显著差异;分别利用600～700 nm和300～500nm波长范围同步荧光光谱进行主成分分析,其对杜仲籽油掺假识别准确率高达100%;利用峰面积与掺假比例建立定量判别分析模型,检测限分别为1%和0. 48%。该方法可实现对杜仲籽油掺假的定性和定量分析,且具有较高的灵敏度、简便和快速等特点。     

荧光光谱法和紫外分光光度法在发酵调味品中苯甲酸含量测定中的应用和比较

对紫外分光光度法和荧光光谱法测定酱油和食醋中苯甲酸含量的方法进行了优化和比较,实验结果表明,荧光光谱最佳发射波长为320 nm,最佳激发波长为225 nm,最佳测定pH为2.6;最优化样品氧化条件为水浴温度为100℃,蒸馏液体积为50 mL,水浴时间为17.5 min;荧光光度法在测定准确度、最低检测限和加标回收率以及检测的方便性都明显优于紫外分光光度法。     

同步荧光光谱法快速鉴别食用油

利用同步荧光光谱法鉴别沙棘果油、沙棘籽油、核桃油、菜籽油、芝麻油、亚麻仁油。结果显示：不同食 用油荧光光谱具有明显的差异,在激发波长250～720 nm范围内,沙棘果油、沙棘籽油、核桃油、亚麻仁油、芝麻 油和菜籽油的最大激发波长范围分别为315～450、520～650、315～490、300～500、300～550、300～490 nm。在 激发光与发射光波长差为90 nm、激发波长250～720 nm的条件下,对6 种不同食用油进行同步荧光扫描,利用主成 分分析得分图可以直观、快速地区分鉴别各种食用油。     

同步荧光法结合主成分分析法鉴别橙汁品质

对鲜榨橙汁与市售某品牌橙汁进行同步荧光扫描得到其三维荧光光谱,并从光谱中提取出3 组特征峰。然后结合其中荧光物质的特性,得知这3 组特征峰对应物质分别为VB2、VB6和黄酮类物质。同时,采用主成分分析法结合于激发波长240～640 nm、发射波长与激发波长差为30 nm条件下扫描而得的同步荧光光谱数据对所有橙汁样品进行聚类并识别,效果良好。结果表明：将荧光光谱技术与光谱模式识别方法相结合,可为橙汁品质鉴别提供有力技术支持。     

二维相关荧光光谱鉴别4种食用植物油种类的研究

采用Cary Eclipse荧光分光光度计检测了4种食用植物油的同步荧光光谱,结合加热时间扰动下的二维相关荧光光谱技术,对一级大豆油、花生调和油、芝麻油和棕榈油,进行了快速无损的识别方法的研究。结果表明,在同步荧光光谱图上,不同植物油的特征吸收峰在出峰数目、出峰位置和峰强上均存在一定的差异;而在二维相关荧光谱图上,由于4种植物油的自动峰及交叉峰的位置、数量和强度不同,其差别体现得更为明显和直观。因此,二维相关图谱法可以作为鉴别不同植物油种类的一种有效方法。     

花生红衣提取物中白藜芦醇的荧光光谱特性分析

建立了一种利用荧光分光光度计检测花生红衣提取物中白藜芦醇的新方法,探讨了白藜芦醇荧光光谱检测的最佳条件,其激发波长和发射波长分别是324.06nm和400.00nm。白藜芦醇产生的荧光强度与浓度在0～1.68×10-5mol/L的范围内具有良好的线性关系,检测限为8.14×10-10mol/L。     

分子荧光法快速定量测定干红葡萄酒中白藜芦醇的含量

建立了一种利用荧光分光光度计检测干红葡萄酒中白藜芦醇的新方法,探讨了白藜芦醇荧光光谱检测的最佳条件,其激发波长和发射波长分别是346.00nm和384.00nm。白藜芦醇产生的荧光强度与浓度在0～1.68×10-5mol/L的范围内具有良好的线性关系,检测限为8.14×10-10mol/L。     

果蔬汁中V_C的测定

建立了一种利用荧光分光光度计检测果蔬汁中VC检测的新方法,用荧光光谱检测VC含量的最佳激发和发射波长分别为342 nm和430 nm。     

冷藏熟肉糜水提液同步荧光光谱的研究

为测量冷藏熟肉糜水提液的同步荧光光谱,采用单因素法考察了不同狭缝宽度、△λ和熟肉糜浓度对同步荧光光谱的影响,分析了鲜肉和不同贮藏时间熟肉糜水提液的特征.结果表明,0.5g冷藏熟肉糜样品,加入0.02%V.溶液10mL,超声提取得到提取液,在△λ70nm、激发狭缝宽度10nm、发射狭缝宽度lOnm的条件下扫描,得到其同步荧光光谱.熟肉糜水提液在326、370、453nm处的同步荧光峰强度随着冷藏时间的延长逐渐增强,可用于冷藏熟肉糜氧化状态的评价.     

Classification of edible oils using synchronous scanning fluorescence spectroscopy

Total luminescence and synchronous scanning fluorescence spectroscopy techniques were tested as regards their ability to characterize and differentiate edible oils, including soybean, sunflower, rapeseed, peanut, olive, grapeseed, linseed and corn oils. Total luminescence spectra of all oils studied as n-hexane solutions exhibit an intense peak, which appears at 290 nm in excitation and 320 nm in emission, attributed to tocopherols. Some of the oils exhibit a second long-wavelength peak, appearing at 405 nm in excitation and 670 nm in emission, belonging to pigments of the chlorophyll group. Additional bands were present in the intermediate range of excitation and emission wavelengths in some oils, arising from unidentified compounds. Similarly, bands attributed to tocopherols, chlorophylls and unidentified fluorescent components were detected in the synchronous-scanning fluorescence spectra. Classification of oils based on their synchronous fluorescence spectra was performed using a non-parametrical k nearest neighbours method and linear discriminant analysis. Both methods provided very good discrimination between the oil classes with low classification error. The results presented demonstrate the capability of the fluorescence techniques for characterizing and differentiating vegetable oils.     

Rapid Quantitative Determination of Walnut Oil Adulteration with Sunflower Oil Using Fluorescence Spectroscopy

Adulteration of walnut oil with sunflower oil is a major issue for the walnut oil industry. In this paper, the potential use of total synchronous fluorescence (TSyF) spectra to differentiate walnut oil from sunflower oil and synchronous fluorescence spectra combined with multivariate analysis to assess the adulteration of walnut oil is demonstrated. TSyF spectra were acquired by varying the excitation wavelength in the region 250–700 nm and the wavelength interval (Δλ) in the region from 10 to 100 nm. TSyF contour plots for walnut oil, in contrast to sunflower oil, show an extra fluorescence region in the excitation wavelength lower than 280 nm. Fifty-one oil mixtures were prepared by adulterating walnut oil with sunflower oil at varying levels (0–100 %). The partial least-squares regression model was used for the quantification of adulteration using wavelength intervals of 20, 40, 60 and 80 nm. This technique is useful for the detection of sunflower oil in walnut oil at levels down to 0.3 % (v/v) in just 2.5 min using an 80-nm wavelength interval.     

地沟油的近红外光谱分析鉴别

通过对地沟油和食用植物油近红外吸收光谱的研究,发现光谱经过基于基线校正和一阶导数的预处理后,食用植物油的885 nm光谱强度值与897 nm光谱强度值之比大于1.4,地沟油则小于1.1,利用这个比值差异,可以区分这两类油;在2 430～2 445 nm和2 465～2 485 nm两个波段,食用植物油有明显的峰值,而地沟油则没有峰值.实验表明,近红外光谱可以用于分辨地沟油和食用植物油.     

原子荧光法测定食用植物油中镉的含量

建立原子荧光光谱法测定食用植物油中镉的含量.利用微波消解样品,对食用植物油中的镉进行原子荧光测定.Cd在0～2.0 ng/mL范围内线性关系良好,相关系数为1.0000,最低检出浓度为0.0078 ng/mL,回收率均在90％以上.该方法简便、快捷、有较高的灵敏度、准确度、精密度和较低的检出限,适合食用植物油中镉含量的...     

固相微萃取-气质联用技术测定5种食用植物油挥发性成分

目的采用气相色谱-质谱(GC-MS)对大豆油、芝麻油、花生油、橄榄油、葡萄籽油5种食用植物油中挥发性成分进行分析。方法采用顶空固相微萃取(HS-SPME)技术对5种食用植物油中的挥发性成分进行萃取,并结合气相色谱-质谱(GC-MS)技术对挥发性成分进行测定。结果 5种食用植物油中共检测出101种挥发性化合物,其中大豆油11种、花生油28种、芝麻油65种、橄榄油25种、葡萄籽油5种。主要包括醛类、酯类、醇类、杂环类、酚类、酸类等10类物质。大豆油中主要的挥发性成分有戊醛、已醛和己酸,花生油中主要的挥发性成分有己醛、2,5-二甲基吡嗪和2,3-二氢苯并呋喃;芝麻油中主要的挥发性成分为5-甲基呋喃醛、2-吡咯甲醛、糠醇、愈创木酚、2-甲基吡嗪、2-乙基-6甲基吡嗪等;橄榄油中主要的挥发性成分为叶醇和4-己烯-1-醇乙酸酯;葡萄籽油中主要的挥发性成分为已醛。结论 5种食用植物油的挥发性物质的种类和含量上有很大区别,可为食用植物油的掺假鉴别提供参考依据。     

Classification of brandies and wine distillates using front face fluorescence spectroscopy

This study demonstrates the use of front face fluorescence spectroscopy and multivariate data analysis for differentiating brandies from wine distillates. Owing to the low price of the wine distillates, they are sometimes used for the counterfeiting brandies. For this reason, there is a need for a rapid method for drink authentication to reassure consumers and protect regional designations. Total luminescence and synchronous scanning fluorescence spectra were recorded followed by a classification of samples using principal component analysis (PCA) and hierarchical cluster analysis (HCA). Both PCA and HCA carried out on the emission spectra (360–650 nm) recorded at excitation wavelength 350 nm and synchronous fluorescence spectra (200–700 nm) collected at wavelength interval 90 nm provide very good differentiation between the two spirit classes. Less good classification was obtained using excitation spectra (225–425 nm) obtained at emission wavelength 440 nm. These results indicate that the front face fluorescence spectroscopy offers a promising approach for the authentication of brandies.     

The increase in oxidative stability of sunflower oil enriched with Nigella sativa L. Seed extracts

Nigella sativa L. seeds are rich sources of phenolic compounds. The aim of this study was to evaluate the efficiency of Nigella seed extract as natural antioxidant compared with butylated hydroxytoluene (BHT) during accelerated oxidation of edible vegetable oils at 120 °C. The modifications during heating were monitored by 3D-front-face fluorescence spectroscopy. The fluorescence spectra were obtained with excitations from 280 to 500 nm and emission wavelengths from 300 to 550 nm and analysed using independent components analysis. Decomposition products formed during heating were also evaluated by means of ¹H-NMR spectroscopy and classic chemical methods such as anisidine value and viscosity. The results of the study clearly indicate that the natural seed extract at a level of 800 ppm exhibited antioxidant effects similar to those of the synthetic antioxidant BHT at a level of 200 ppm and thus contributes to an increase in the oxidative stability of the oil.