利用太赫兹技术和统计方法鉴别地沟油

基于普通食用油和地沟油的太赫兹吸收光谱,利用0.16~1.30 THz频域的吸收谱,进行聚类分析,8种地沟油组成一类,食用油自成一类。随机选择了2种地沟油作为验证样品,将其余油样进行聚类,采用概率神经网络法对验证样品进行判定,并成功将2种油判定为地沟油。结果表明,太赫兹时域光谱技术结合统计方法可推广成为鉴别地沟油的快速有效手段。     

应用脂肪酸甲酯快速筛选植物油中掺假地沟油

根据植物油和地沟油中脂肪酸酯存在方式的不同,建立植物油中地沟油掺假的快速筛选方法。植物油中脂肪酸是以甘油三酯的形式存在,地沟油中脂肪酸以脂肪酸甲酯的形式存在,利用气相色谱-质谱的全扫描模式,结合NIST 05标准谱库检索功能,对37 种脂肪酸甲酯进行测定。样品采用直接稀释-气相色谱-质谱全扫描分析脂肪酸甲酯,100 个植物油样品中均未检出脂肪酸甲酯;20 个地沟油样品中13 个检出肉豆蔻酸甲酯（C14∶0）、棕榈酸甲酯（C16∶0）和硬脂酸甲酯（C18∶0）等14 种脂肪酸甲酯,检出率为65%,且70%的检出脂肪酸甲酯的地沟油样品中脂肪酸甲酯种类多、含量较高。因此,若植物油样品脂肪酸甲酯种类多、含量高,则可判定为有地沟油掺假;若脂肪酸甲酯含量低或没有脂肪酸甲酯,则可以进一步用其他指标和方法进行检测,脂肪酸甲酯的检测方法可以作为地沟油掺假的快速粗筛方法。     

南路边茶高效液相色谱指纹图谱的建立

应用高效液相色谱法初步建立了南路边茶的指纹图谱。采用线性梯度洗脱,乙腈和0．3％甲酸水溶液为流动相,柱温为30℃,检测波长为280nm,流速为1．0mL／min。根据平均相对保留时间、共有峰、平均相对峰面积等对色谱指纹图谱进行了分析。方法的精密度、重复性和稳定性良好。通过对48批不同生产企业、不同生产年限的南路边茶样品进行分析,以咖啡碱为参照峰,共确定了37个色谱峰作为南路边茶的特征指纹峰。运用相似度评价和聚类分析法对各批次南路边茶样品指纹图谱进行了化学模式识别研究。各批次南路边茶样品与对照指纹图谱共有模式的相似度均大于0．90;对相对峰面积的聚类分析结果表明,当临界值为15时,48批南路边茶样品可聚为2类。该研究为南路边茶的鉴别和质量控制提供了参考。     

基于聚类分析的白茶高效液相色谱指纹图谱研究

采用高效液相色谱法对白茶样品中儿茶素类和生物碱类成分进行分析,建立白茶的特征性指纹图谱,为白茶的质量评价提供参考依据。以福鼎、政和等地的多种类白茶为样品,经提取溶剂、流动相、波长、流速、柱温等条件筛选,确定白茶指纹图谱高效液相色谱条件为:用70%甲醇在70 ℃条件下进行提取,色谱柱为Agilent Eclipse Plus C₁₈（4.6 mm×250 mm,5 μm）,以乙腈-0.5%乙酸为流动相进行梯度洗脱,检测波长258 nm,柱温35 ℃,进样量为10 μL;咖啡碱作为参照峰,计算共有峰相对保留时间和相对峰面积;选取中药色谱指纹图谱相似度评价系统（2012版）进行相似度评价;采用系统聚类分析法（Hierarchical cluster analysis,HCA）对其进行聚类分析。建立了白茶高效液相色谱法的指纹图谱,确认了28个共有峰;相似度评价结果显示,12批不同品种白茶相似度在0.98以上,表明不同年份不同产地的白茶样品成分组成一致;对没食子酸（Gallic acid,GA）、咖啡因（Caffeine,CAF）、表儿茶素（Epicatechin,EC）、表儿茶素没食子酸酯（Epicatechin gallate,ECG）、表没食子儿茶素没食子酸酯（Epigallocatechin gallate,EGCG）、表没食子儿茶素（Epigallocatechin,EGC）六个成分进行了峰指认;系统聚类分析结果表明,存放时间对白茶成分的组成及含量有一定的影响,聚类分析将测定的白茶样品分为两类,2013、2014年为一类,2017~2020年为一类。该方法方便、快捷、简单、准确可靠,可为白茶的质量控制提供参考依据。     

卷烟挥发性成分的聚类分析

采用同时蒸馏萃取-气相色谱/质谱法对11种卷烟样品的挥发性成分进行了分析,并采用SPSS软件按欧式距离类平均法对90个成分峰进行了聚类分析。结果表明:11种卷烟样品可以聚为6个类别,恰好与其品牌和生产企业相对应,即同一个生产厂家同一品牌的卷烟样品可以很好地聚为一类。该法可为卷烟品牌的区别、品质控制、综合评估和真伪鉴别提供参考。     

基于脂质聚类分析的可可粉掺假检测方法研究

为从脂质指纹分析角度建立可可粉掺假检测方法,用索氏提取法提取可可粉中的可可脂,通过反相高效液相色谱(RP-HPLC)分离-蒸发光散射检测器(ELSD)检测,构建可可粉的脂质色谱指纹图谱,根据其共有特征峰的相对峰面积,应用系统聚类分析(HCA)法,对模拟分别掺入板栗壳粉与桂圆壳粉且分别掺入代可可脂和棕榈油的可可粉掺假样品进行脂质指纹分析和掺假鉴别试验。结果表明:该方法对掺入1.2%(占样品质量的百分含量)及以上代可可脂或棕榈油的掺假可可粉样品可以予以鉴别。该方法较简便、灵敏且重复性好,可用于掺入不含脂质或低脂质类杂质的伪劣样品的检测。     

可可粉色谱指纹图谱的构建及其质量控制中的应用

目的:建立可可粉高效液相指纹图谱。方法:采用RP-HPLC法。色谱柱为Agilent ZORBAX Extend-C18(250mm×4.6mm,5μm);以乙腈-0.05%磷酸缓冲盐溶液为流动相梯度洗脱;柱温:30℃;流速:0.8mL/min;检测波长:210nm;进样量:10μL。测定10批不同来源可可粉图谱,并运用相似度分析、系统聚类分析对可可粉进行分类研究。结果:建立了精密度、稳定性和重复性均良好的HPLC指纹图谱,确立了5个共有峰,指认了其中3个色谱峰,并建立了可可粉指纹图谱共有模式,测得各批次样品指纹图谱相似度均在0.90以上,系统聚类分析将10批可可粉分为3类。结论:该方法简便易行、准确、重现性好,可以作为可可粉质量评价的重要依据。     

基于赣南脐橙指纹图谱的主成分及UPLC-Q-TOF-MS分析

建立不同产地赣南脐橙的指纹图谱,对其进行主成分分析,并采用超高效液相色谱-四级杆飞行时间质谱(UPLC-Q-TOF-MS)分析共有峰成分。采用色谱柱为Agilent-C18 column (2.1 mm×100 mm,1.8μm),流动相为0.1%甲酸水溶液(A)-甲醇(B)进行梯度洗脱,柱温35℃,流速0.3 m L/min,检测波长254 nm,质谱以正离子模式进行全扫描。以色谱图构建赣南脐橙指纹图谱,对其相似度研究,并对指纹图谱上的共有峰进行主成分分析。结果表明,14批赣南脐橙样品的指纹图谱中有21个共有峰,样品与对照指纹图谱相似度均在0.90以上。通过相似度分析,可以有效区分非赣南脐橙。样品经主成分分析,得到4个主成分,其累计方差贡献率为85.75%,并可将样品分为4类。通过分析正离子质谱信息,结合相关文献报道,推断并鉴定出3个共有峰的化合物。该方法准确、可靠,重现性好,所建立的指纹图谱结合主成分分析可用于赣南脐橙的专属性鉴定和其产地的区分。     

高效液相色谱串联质谱仪在食品检验中的优势与局限

<正>高效液相色谱串联质谱仪是一种将液相色谱与质谱技术相结合的仪器,具有高分辨率、高灵敏度、高自动化等优点。该仪器主要由高效液相色谱部分和串联质谱部分组成,高效液相色谱部分主要用于样品的分离和纯化,而串联质谱部分则用于样品的检测和分析。高效液相色谱串联质谱仪的工作原理是将样品经前处理后,进入高效液相色谱部分进行分离和纯化。分离后的组分依次进入质谱部分,首先通过离子源被电离成离子,然后进入质量分析器进行质量分析。质量分析器按照质量/电荷比分离离子,并将分离后的离子送入检测器检测和计数。通过记录的质谱图和色谱图,可以进一步分析和鉴定样品。     

液相色谱-质谱联用法测定保健食品中 9种脂溶性维生素

目的建立同时测定保健食品中9种脂溶性维生素的液相色谱-质谱联用法。方法用适合的有机溶剂充分溶解试样中的脂溶性维生素,超声提取一段时间后,经液相色谱-质谱联用仪进行测定。采用标准样品定量离子外标法定量,以ACQUITY UPLC BEH C_(18)色谱柱,对色谱条件、质谱条件进行优化后,通过分子离子峰、二级碎片、色谱保留时间等信息,对片剂、软胶囊基质中的9种脂溶性维生素进行定量测定。结果 9种脂溶性维生素标准品溶液浓度和检测响应的线性关系良好,其相关系数r均大于0.99;检出限为0.226~23.5μg/L,定量限为1.79~70.6μg/L,方法准确度、精密度、重复性均可满足要求。结论运用液相色谱质谱联用法可同时测定保健食品中的9种脂溶性维生素,并在很大程度上简化了提取过程、提高了实验效率,该方法快捷、简便、准确。     

地沟油鉴别检测方法研究进展

近年来,随着生活水平的越来越高,食品安全问题越来越受到人们的重视。地沟油是目前我国食品安全非常关注的问题之一。本文简要地概述了地沟油的概念、种类及其危害,对目前地沟油的鉴别和检测方法进行综述。本文通过对当前多种检测方法(傅里叶变换红外光谱分析法、脂肪酸组成分析法等)的综合比对,发现现有这些方法并不能准确鉴定地沟油。此外,对地沟油鉴别存在的难点进行分析。最主要的技术难点有两处:(1)经深度精炼,地沟油中的可以用来检测的物质大部分都除去了,很多方法对于深度精炼地沟油的检测不适用。(2)有些方法只适用于部分特定来源的地沟油,不具有广泛的意义。以期寻求一种快速可行,具有广泛代表性的地沟油检测方法。     

“地沟油”常见检测方法及低场核磁共振法的研究进展

“地沟油”是中国近期发生的严重食品安全问题之一, 目前尚无非常有效的地沟油检测方法。本文在分析了地沟油检测重要性的基础上, 从感官检验、理化检验及仪器方法三个方面对目前国内外报道的“地沟油”鉴别检验方法进行了综述, 并分析了各种方法的特点及存在的问题。重点对低场核磁共振技术的工作原理及其在油脂品质监控方面的研究进展进行了介绍, 旨在为“地沟油”的鉴别检测方法提供有益参考及研究思路。     

A survey of the use of soy in processed Turkish meat products and detection of genetic modification

To screen for possible illegal use of soybeans in meat products, the performance characteristics of a commercial polymer chain reaction (PCR) kit for detection of soybean DNA in raw and cooked meat products were established. Minced chicken and beef products containing soybean at levels from 0.1% to 10.0% were analysed by real-time PCR to amplify the soybean lectin gene. The PCR method could reliably detect the addition of soybean at a level of 0.1%. A survey of 38 Turkish processed meat products found only six samples to be negative for the presence of soybean. In 32 (84%) positive samples, 13 (34%) contained levels of soy above 0.1%. Of soybean positive samples, further DNA analysis was conducted by real-time PCR to detect whether genetically modified (GM) soybean had been used. Of 32 meat samples containing soybean, two samples were positive for GM modification.     

多维灰聚类法与定性分析在熟肉制品安全风险 评估中的应用

目的 对2015年某省内生产销售的熟肉制品进行检验,并对检验结果进行安全风险评估。方法 对熟肉制品生产过程中容易出现的风险点进行定性分析, 从而确定熟肉制品的风险因素, 利用多维灰色聚类法对影响食品安全的主要风险因素进行定量评估, 探讨影响熟肉制品有害因素的主次关系。结果 评估结果显示抽检中不合格样品大多属于低风险类, 可以得出熟肉制品的食品安全状况属于安全可控状态。结论 该法明确了食品安全风险的等级, 为食品安全控制做出前瞻性、有效性的技术支撑, 对今后风险评估工作的开展具有切实可行的实践意义。     

基于可见—近红外光谱的花生油二元掺伪体系鉴别研究

为了建立一种简便有效的花生油掺伪的定性和定量鉴别方法,采集花生油中分别掺伪0~90%大豆油、棕榈油和棉籽油样品的可见—近红外光谱图,结合主成分分析、判别分析、改进偏最小二乘法,建立花生油掺伪的定性鉴别和定量预测模型。结果表明,在定性鉴别中,对花生油中分别掺入大豆油、棕榈油和棉籽油的整体正确判别率分别达到了100%、96.1%和85.3%。在定量分析中,对MPLS法建立的花生油二元掺伪定标模型进行验证,结果表明,掺入大豆油、棉籽油和棕榈油的预测相关系数R_p~2分别为0.998、0.997和0.995,相对标准差RSD分别为2.33%、3.04%和3.83%,相对分析误差RPD分别为3.542、2.642和2.581,说明这三种掺假花生油所建立的最优定标模型的预测精度高,其中花生油中掺入大豆油的预测精度最高,检测花生油中掺入棉籽油与棕榈油的最低掺假量为3%。为花生油二元掺伪模式提供了一种简便、快速、有效的分析方法。     

Relationship between the solubility,dosage and antioxidant capacity of carnosic acid in raw and cooked ground buffalo meat patties and chicken patties

Antioxidant capacity of oil soluble and water dispersible carnosic acid (CA) extracted from dried rosemary leaves using HPLC was evaluated at two different dosages (22.5 ppm vs 130 ppm) in raw and cooked ground buffalo meat patties and chicken patties. Irrespective of total phenolic content, CA extracts reduced (p < 0.05) the thiobarbituric acid reactive substances (TBARS) by 39%–47% and 37%–40% in cooked buffalo meat and chicken patties at lower dosage (22.5 ppm) relative to control samples. However, at higher dosage (130 ppm) the TBARS values were reduced (p < 0.05) by 86%–96% and 78%–87% in cooked buffalo meat and chicken patties compared to controls. The CA extracts were also effective in inhibiting (p < 0.05) peroxide value and free fatty acids in cooked buffalo meat and chicken patties. The CA extracts when used at higher dosage, were also effective in stabilizing raw buffalo meat color.     

Discrimination of cinnamon bark and cinnamon twig samples sourced from various countries using HPLC-based fingerprint analysis

A simple and efficient HPLC method was developed to evaluate the quality of traditional herbal medicines made from cinnamon bark (CB) and cinnamon twig (CT). Seven major bioactive ingredients in 56 samples (24 CB and 32 CT) collected from China, Vietnam, and Indonesia were separated and quantified. The method was validated following the International Conference on Harmonisation (ICH) guidelines. A fingerprint analysis method to discriminate between CB and CT using major component content levels was developed. The discrimination process included the use of similarity indices and partial least-squares discriminant analysis (PLS-DA). Classification accuracy by the PLS-DA method was about 98%. The pattern analysis method was specific and could be readily used for the comprehensive evaluation of cinnamon samples. Therefore, an HPLC fingerprint in combination with pattern analysis provides a very flexible and reliable method for quality assessment of herbal drugs.     

基于低共熔溶剂的液液微萃取技术测定食用油中的新烟碱类杀虫剂

利用合成的低共熔溶剂（deep eutectic solvent,DES）作为液液微萃取技术中的萃取剂,利用超声波辅助分散,建立高效液相色谱测定食用油中4?种新烟碱类杀虫剂（噻虫嗪、吡虫啉、啶虫脒、噻虫啉）的方法。首先将合成的DES加入到含有目标分析物的食用油（正己烷稀释）中,进行超声辅助分散加速提取,然后离心,吸出上层液体,再用微量注射器吸取DES富集相（下层）进行液相色谱分析。根据单一变量法,对影响萃取效率的一些因素进行优化,如DES的种类和体积、超声萃取时间、离心时间等。在最佳条件下,回收率在81.9%～98.0%之间,相对标准偏差为5.5%～8.3%（n=5）,检出限范围为3.2～5.3?μg/L,定量限范围为10.8～17.7?μg/L。并且应用所建立的基于DES超声辅助分散液液微萃取方法检测食用油实际样品大豆油、葵花籽油、亚麻籽油中的新烟碱类农药。此方法提取和浓缩一步完成,避免了毒性较大的有机溶剂的使用,具有快速、简单、有效等显著优点。     

Effect of different air/steam convection cooking methods on turkey breast meat: physical characterization, water status and sensory properties

Turkey breast samples were cooked using a forced convection oven at three relative humidity levels (RH=8, 35 and 88%) at 100°C. Cooking parameters (temperature, cook value, and yield), textural and sensory properties as well as water status of the samples were evaluated. The application of different RH levels resulted in different cooking performances and cooked meat quality. Low steam cooking conditions (RH=35%) significantly increased cooking yield (7% higher than the high steam cooking), moisture content and water-holding capacity and had a positive effect on perceived tenderness, as shown by sensory analysis, where steam cooked samples were perceived as the most tender. The more mobile protons of (1)H T(2) (relaxing at times longer than 1s) in low steam samples were related to the higher perceived tenderness. Low steam cooking allowed for less water consumption, making this process an attractive cooking method as compared to high steam, as it also resulted in higher quality cooked turkey meat.     

Effects of cross-linked tapioca starches on batter viscosity and oil absorption in deep-fried breaded chicken strips

In this study, the effectiveness and feasibility of using various degrees of cross-linked tapioca starches in batter and breading formulations to reduce oil absorptions in deep fried chickens were investigated. Shear flow behaviour, water retention capacity (WRC), pick-up as well as cooked yield of the prepared batters were also examined. Flow curves showed that all studied batters were pseudoplastic, i.e. having shear thinning characteristics. In addition, it was found that the substitution of 20% (w/w) cross-linked starches for wheat flour in the batter formulation significantly reduced the consistency index and WRC of the batters. However, batter pick-up and cooked yield values were insignificantly affected. Oil uptake of fried chicken crusts was determined using differential scanning calorimetry due to its specific advantages over the conventional solvent extraction method. In comparison to the control (wheat) formulation, crusts of fried chicken samples obtained from the formulations containing 20% (w/w) cross-linked starch showed significantly lower oil content by at least 17% relative oil reduction. The highest relative oil reduction was found in the batter containing the highly cross-linked tapioca starch. Furthermore, an increase in water content in the batter formulations resulted in a reduction in the batter pick-up, cooked yield and oil absorption. The degree of cross-linking which in turn resulted in the limited starch granule disintegration is the predominant factor in the reduction of oil content for deep-fried battered food.