量子点标记荧光免疫法检测花生中黄曲霉毒素B_1

建立了基于量子点标记二抗的间接竞争荧光免疫吸附测定方法（indirect competitive fluorescence-linked immunosorbent assay,cFLISA）,并研究检测花生中黄曲霉毒素B1的可行性。采用谷胱甘肽为稳定剂,在水相中直接合成碲化镉（CdTe）量子点,并利用1-（3-二甲氨基丙基）-3-乙基碳二亚胺盐酸盐（EDC）与兔抗鼠二抗进行共价偶联,以黄曲霉毒素B1的单克隆抗体建立cFLISA方法。结果表明,该方法的灵敏度和最低检测限值分别为0.023ng/mL和0.001ng/mL,与传统的有机染料FITC-二抗法比较,灵敏度提高了30倍,花生样品加标0.1、0.05和0.025ng/g,回收率范围在88%～116%之间,变异系数均小于10%。建立的cFLISA方法可以较好的检测花生中黄曲霉毒素B1,并为其它真菌毒素的检测提供参考。     

HPLC determination of ochratoxin A in high consumption Tunisian foods

Samples (180) of high consumption food commodities from various regions of Tunisia were analysed to determine ochratoxin A contamination levels. A high performance liquid chromatography method for ochratoxin A determination was optimized. Samples were extracted with acetonitrile/water (80:20, v/v) solution and purified by immunoaffinity column. Average recoveries at 0.5 and 2 ng/g levels ranged from 84 ± 3.1 to 94 ± 1.2% with a between-day coefficient of variation (RSDR) of 3.8%. The method detection limit was 0.1 ng/g and ochratoxin identity was confirmed by methyl ester formation. The whole procedure was simple and fast if compared with other existing procedures. Performed analysis indicates that 45% of monitored samples were contaminated with levels ranging from 0.11 to 33.9 ng/g. The most contaminated commodities were barley, sorghum and wheat.     

Multimycotoxin analysis of sorghum (Sorghum bicolor L. Moench) and finger millet (Eleusine coracana L. Garten) from Ethiopia

The natural contamination of sorghum and finger millet by toxigenic fungi and associated mycotoxins has been studied. All the tested sorghum and finger millet samples were found to be contaminated by Fusarium and Aspergillus species. Sorghum was considerably more likely to be contaminated by both genera than finger millet. Penicillium, Alternaria, Rhizopus and Epicoccum species were also present in both grains albeit at lower frequencies. Multimycotoxin analysis using LC–MS/MS revealed the contamination of sorghum and finger millet by 84 and 62 metabolites, respectively. The prevalence of major mycotoxins was lower than 15% in sorghum except zearalenone that occurred in one third of the samples at average level of 44 μg/kg. In finger millet major mycotoxins occurred at a prevalence of 6–52% with zearalenone being the dominant and occurring at average level of 76 μg/kg. Aflatoxins B₁, B₂, G₁, G₂ and M₁ were detected in at least one sorghum sample while only aflatoxins B₁ and G₁ were present in finger millet samples. The average aflatoxins B₁ and G₁ concentrations in sorghum have been higher than European standards. But the level of B₂, G₂ and M₁ in sorghum and that of B₁ and G₁ in finger millet have been lower. Apart from aflatoxin precursors and other Fusarium metabolites, a broad range of additional metabolites were detected in sorghum and finger millet.     

A Sensitive Immunoaffinity Column-Linked Indirect Competitive ELISA for Ochratoxin A in Cereal and Oil Products Based on a New Monoclonal Antibody

A new sensitive monoclonal antibody (mAb) 1H2 against ochratoxin A (OTA) was reported herein. This mAb belonged to the immunoglobulin G1 (k chain) isotype. In the optimized indirect competitive enzyme-linked immunosorbent assay (icELISA), 1H2 showed a 50 % inhibition concentration (IC₅₀) value of 0.058 ng/mL and a detection limit (IC₁₀) of 0.001 ng/mL. The cross-reactivity of 1H2 with ochratoxin B, aflatoxins, deoxynivalenol, zearalenone, T-2 toxin, or fumonisins was below 0.3 %. Based on this mAb, an immunoaffinity column (IAC)-linked icELISA was developed for OTA detection in the cereal and oil products. The working range of the assay for solid sample was 0.36–16 μg/kg. The recoveries from spiked samples of IAC-linked icELISA ranged from 83 to 101 %. These recoveries were much higher than those of icELISA (21–78 %) and in good agreement with those obtained by using the standard high-performance liquid chromatography method (87–110 %). The results indicated that the mAb 1H2 had the values for studies of OTA in the crude agricultural products.     

Development of a colloidal gold strip for rapid detection of ochratoxin A with mimotope peptide

Ochratoxin A (OTA), a mycotoxin mainly produced by some Aspergillus and Penicillium species, is found in cereals, coffee, wine, pork and grapes. The kidney and liver are the target organs of OTA, resulting in teratogenicity, carcinogenicity, and mutagenicity. To avoid the risk of OTA consumption, raw materials should be identified and removed from distribution. Current procedures for detection of OTA are time-consuming and involve sophisticated equipment. Furthermore, materials containing OTA is a biohazard for manufacturers and consumers. In this study, a rapid, inexpensive, and user-friendly lateral flow strip assay ideally suited for on site testing of OTA was developed. Moreover, mimotope peptide capable of mimicking OTA by panning from a M13 phage-displayed random seven-peptide was used instead of OTA–protein conjugate. Ten ppb of OTA was detected in 10 min by this new strip. The results indicated that a rapid method without using the mycotoxin, but using mimotope peptides was developed to screen OTA; related methods also can be developed to screen other mycotoxins.     

离子迁移谱法快速鉴别煎炸老油

目的建立基于离子迁移谱的快速鉴别煎炸老油的鉴别方法。方法油样经正己烷50倍稀释、混匀,进样量为4.0μL,在进样口温度为170℃,迁移管温度为60℃的离子迁移谱条件下进行检测,样品测试时间为20 s。将采集的油样离子迁移谱图利用化学计量学方法进行分析,建立煎炸老油鉴别模型。结果运用主成分分析法(PCA)对两类油脂的谱图信息进行分类,两类油脂能明显分开,效果良好。采用递归支持向量机法(R-SVM)对煎炸老油建立判别模型,十折交互检验正确判别率最高达98.8%。结论本方法无需复杂前处理、检测时间短,有机试剂用量小,操作简单快速,结合化学计量学的分析方法建立的煎炸老油的鉴别模型准确度高,适用于煎炸老油的快速鉴别,为我国食用油质量安全监管提供了一种新方法。     

液相芯片及其在粮油主要真菌毒素同步检测中的应用

液相芯片整合了分子生物学、免疫学、高分子材料、微流控技术、高速数字信号处理、计算机分析等多方面技术,可实现少量样本高通量定性定量检测。本文主要阐述液相芯片定性与定量分析的基本原理、特点及其在分析领域的应用现状,探讨液相芯片在小分子高通量分析中的工作模式及其当前技术难点,分析黄曲霉毒素等粮油主要真菌毒素免疫分析研究进展,指出液相芯片在粮油主要真菌毒素检测中将有广泛的应用前景。     

Physicochemical characteristics of palm oil and sunflower oil blends fractionated at different temperatures

This research was carried out to determine the effect of fractionation temperature on the physicochemical characteristics of refined, bleached and deodorized (RBD) palm oil and sunflower oil blends fractionated at different temperatures. Blends of 20% and 40% sunflower oil with 80% and 60% RBD palm oil, respectively, were fractionated at three different temperatures (15, 18 and 21 °C). The results showed that olein with higher iodine value was obtained at lower fractionation temperature. This was because, at lower fractionation temperature, more of the polyunsaturated fatty acid, namely linoleic acid (C18:2), went into the liquid fraction. On the other hand, more of the saturated fatty acid, namely palmitic acid (C16:0), went into the liquid fraction at higher fractionation temperature. Blending reduced the triacylglycerol composition, namely POP, POS, SOO and PLP, while OLO, PLL, OLL and LLL/LLnO increased. Lower fractionation temperature decreased the composition of monosaturated triacylglycerol and increased the composition of di- and polyunsaturated triacylglycerols. Lower fractionation temperature produced a liquid fraction with lower solid fat content and lower cloud point than did higher fractionation temperature.     

改进的无溶剂微波提取-全二维气相色谱/飞行时间质谱分析油菜籽和花生中挥发油

建立了改进的无溶剂微波提取-全二维气相色谱/飞行时间质谱分析油菜籽和花生中挥发油的方法。使用羰基铁粉作为提取剂提取油料样品中的挥发油,实现无溶剂快速提取。经优化得到,羰基铁粉与样品的质量比为1:5;全二维气相色谱/飞行时间质谱(GC×GC/TOF MS)选择柱系统DB-5MS柱和DB-17柱,调制周期4s,初始温度35℃。将改进的无溶剂微波提取法(ISFME)与常规的无溶剂微波提取法(CSFME)进行比较。结果表明ISFME法更快捷,提取两种油料挥发油只需20min,而CSFME法需要50min;而且ISFME法能耗明显小于CSFME法。经GC×GC/TOF MS鉴定得出,两种方法提取样品挥发油的主要化学成分一致,均鉴定出大量杂环类物质、氧化挥发物(醇、醛、酮、酸、酯、烃)、含S、N物和苯环类物质等成分,其中杂环类占主要地位。ISFME法提取挥发油的氧化挥发物相对含量较多,更易于生成较多的香味物质。     

28种功能性食用油脂肪酸组成研究

目的研究28种功能性食用油脂的脂肪酸组成,包括8种国家新食品原料(新资源食品)目录油脂。方法采用气相色谱-氢火焰离子化检测器(gas chromatography-flame ionization detection,GC-FID)方法对28种油脂的脂肪酸组成进行研究。在GC-FID图谱基础上,得出了所测的28种植物油脂中37种脂肪酸的指纹图谱。根据脂肪酸的保留时间和峰面积进行定性和相对定量,进而分析饱和脂肪酸(saturated fatty acid,SFA)、不饱和脂肪酸(unsaturated fatty acid,UFA)、多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)、单不饱和脂肪酸(monounsaturated fatty acid,MUFA)组成,从而分析样品的脂肪酸组成。结果在28种功能性油脂中,芍药籽油、芥花油、美藤果油、文冠果油、星油藤种子、翅果油等10种油脂UFA含量都在90%以上;MUFA含量最高为澳洲坚果油80.3%,其中,PUFA含量以美藤果油最多,达到82.0%,星油藤种子油次之,为81.1%,二者亚油酸(C18:2)和亚麻酸(C18:3)均含量高达40%;漆树种仁油、毗黎勒油、秋葵籽油、油瓜油的SFA含量均超过30%。结论该研究对探讨利用脂肪酸指标评价新型功能性油脂的营养价值及其开发利用具有指导意义。