A reliable and sensitive time-resolved fluorescent immunochromatographic assay (TRFICA) for ochratoxin A in agro-products

Immunochromatographic assays (ICAs) are considered as a suitable diagnostic tool for the detection of mycotoxins. Mycotoxins and especially, ochratoxin A are analytes with more demanding sensitivity requirements. To enhance the sensitivity of current immunochromatographic assays for ochratoxin A (OTA), a novel sensitive ICA was developed in this study. In the assay, microspheres enclosing fluorescent europium (III) [Eu(III)] nanoparticles (EuNPs) were used as a label for OTA monoclonal antibody (OTA-mAb) conjugation. Accordingly, assay was called time-resolved fluorescent immunochromatographic assay (TRFICA). The test strip was composed of three parts: a sample pad, nitrocellulose membrane and an absorbent pad. As for detection, a proper concentration of conjugated microspheres was pipetted into the microtube and sample extract was added to it. Then the strip was inserted into the tube and the fluid flow along the strip. The TRFICA results were obtained in 8 min and read by a portable TRFICA strip reader. The established method allows quantitative determination of OTA with limit of detection as low as 1.0 μg kg⁻¹ in the samples. For validation, spiked samples including wheat, maize, soybean and rice were respectively assayed by TRFICA and a standard high performance liquid chromatography equipped with a fluorescence detector (HPLC-FLD), and good agreement of results was obtained between two methods.     

玉米醇溶蛋白-多酚相互作用及复合物制备与表征

采用荧光分光光度计、紫外分光光度计等探究玉米醇溶蛋白与3种多酚在醇溶体系以非共价方式结合机理及其对蛋白质结构及抗氧化性的影响,并且通过浊度、粒径及微观形貌等指标对其形成的复合胶体颗粒进行表征,初步探讨多酚对玉米醇溶蛋白胶体颗粒自组装的影响.结果 表明:将多酚引入玉米醇溶蛋白体系后,蛋白质发生荧光猝灭现象,猝灭类型主要为...     

亚临界r134a-丁烷萃取菜籽饼中脂质 微量成分工艺研究

以菜籽饼为原料，以微量成分Canolol、生育酚和植物甾醇萃取量为评价指标，研究r134a与丁烷质量比对亚临界混合溶剂萃取的影响。在此基础上，利用正交实验优化得到最佳萃取工艺条件为：r134a与丁烷质量比6∶ 3，萃取温度45 ℃，萃取时间30 min。在最佳条件下，Canolol、总生育酚和总植物甾醇萃取量分别为2.43、9.71、89.17 mg/100 g。     

开环异落叶松树脂酚的提取及其对乳液稳定性的影响研究

以含50%开环异落叶松树脂酚二葡萄糖苷(SDG)的亚麻木酚素粗提物(50%SDG)为水解原料,对制备开环异落叶松树脂酚(SECO)粗提物的HCl浓度和水解时间进行优化,进一步通过溶剂萃取、真空冷冻干燥工艺制备SECO粗提物,并将其应用于磷脂-亚麻籽油乳液体系中,研究水解前后亚麻木酚素粗提物对磷脂-亚麻籽油乳液在65℃高温储藏过程中稳定性的影响。结果表明:在HCl浓度1 mol/L、水解时间120 min的条件下水解,可制备SECO含量为65%的SECO粗提物(65%SECO);在磷脂-亚麻籽油乳液高温储藏(65℃)过程中,65%SECO组乳液粒径无显著变化,但对照组和50%SDG组乳液粒径增大;与对照组乳液相比,储藏7 d,65%SECO和50%SDG可分别将乳液中氢过氧化物含量降低11%和27%。由此可见,在磷脂-亚麻籽油乳液的高温储藏(65℃)过程中,50%SDG具有较好的抑制油脂氧化的效果,但通过水解制备的65%SECO能显著提高磷脂-亚麻籽油乳液的物理稳定性。     

Desalted duck egg white nanogels combined with κ-carrageenan as stabilisers for food-grade Pickering emulsion

There was an extensive interest in food-grade Pickering emulsions formulated by natural stabilisers owing to the gradual growing demand for pursuing green-label products. Based on this, the desalted duck egg white nanogels (DEWN) combined with κ-carrageenan (CAR) (CAR/DEWN) were used as stabilisers to prepare environment-friendly Pickering emulsions. The DEWN and CAR/DEWN as well as the particles-stabilised emulsions were all characterised. Compared with the DEWN- and CAR-stabilised emulsions, Pickering emulsions based on CAR/DEWN were investigated to illustrate the long-term stability according to the results of visual appearance, static multiple light scattering and centrifugation experiments. In addition, CAR/DEWN could prepare stable high internal phase emulsions, which may give a new perspective for nutraceutical or drug encapsulation and delivery. Adding CAR to the DEWN not only increased the apparent viscosity of the emulsions to 122.2% but also enhanced the thixotropic recovery rate to 87.7%. In general, CAR/DEWN as stabilisers significantly promoted the Pickering emulsions' properties, and provided a possibility for the application of Pickering emulsion in foods.     

Diminution of aflatoxin B1 production caused by an active packaging containing cinnamon essential oil

The antifungal and antimycotoxigenic action of an active package containing cinnamon essential oil have been evaluated against the mold Aspergillus flavus on the aflatoxin B1 production. Two independent experiments were carried out, the first one with cinnamon on a paper diffusion disc placed in vapor phase and the second one with an active PP (Polypropylene) films containing the essential oil. The culture media, exposure time, closure of the Petri dish and cinnamon concentration were evaluated. The first experiment revealed an important reduction on mycotoxin, even when the mold grew, and the action remained for 15 days. The second experiment highlighted the importance of cinnamon concentration on the antimycotoxigenic action, achieving a strong reduction with the sub-inhibitory concentration (2% of cinnamon) and a complete reduction with fungicidal concentration (4% and 6% cinnamon). The UPLC system coupled to a fluorescence detector was optimized for analysis of aflatoxin B1.     

微量成分形成的反胶束对亚麻籽油氧化稳定性的影响

以富含α-亚麻酸的亚麻籽油为研究对象,测定多种微量成分（磷脂、油酸、β-谷甾醇、二酰基甘油）在stripped亚麻籽油中的临界胶束浓度,并研究反胶束的形成对亚麻籽油氧化稳定性以及生育酚抗氧化活性的影响。结果表明,磷脂是形成反胶束的重要组分,其临界胶束浓度为125 μmol/kg;与对照组相比,低浓度（低于临界胶束浓度）微量成分对亚麻籽油的热稳定性无显著影响,但形成反胶束后则能显著降低油脂的起始氧化温度（约12%）以及氧化诱导时间（约33%）,增加贮藏过程中氢过氧化物（约36%）、丙醛（约13%）和己醛（约200%）的含量,显示出促氧化活性;与对照组相比,生育酚的添加能抑制油脂氧化进程,但反胶束的形成使油脂中氧化产物浓度高于对照组,降低了生育酚的抗氧化活性。因此控制亚麻籽油中反胶束的形成将有助于油脂氧化稳定性,为富含n-3多不饱和脂肪酸油脂的稳态化控制提供新的策略与途径。     

NAPUS 2000. Rapeseed (Brassica napus) breeding for improved human nutrition

Following a competition announcement of the Federal Ministry of Research and Education (BMBF) a project dealing with the improvement of the nutritional value of oilseed rape (Brassica napus) for human food applications was worked out and started in autumn 1999. Seventeen partners from different working areas are carrying out a complex project reaching from the discovery, characterisation, isolation and transfer of genes of interest up to breeding of well performing varieties combined with important agronomic traits. Economic studies and processing trials as well as nutritional investigations of the new qualities are carried out. B. napus seed quality aspects with respect to seed coat colour, oil composition, lecithin and protein fractions and antioxidants like tocopherols and resveratrol will be improved. The first results indicate that it is possible to select suitable plant material with certain seed compositions for an efficient implementation of genetic transformation.     

钙离子对亚麻籽胶-紫苏分离蛋白负载DHA藻油乳液储藏特性与递送虾青素效果的影响北大核心CSCD

DHA藻油是补充ω-3多不饱和脂肪酸的重要非动物来源,但因其自身水溶性差、易氧化产生不良风味等特点,极大约束了其摄入途径。据此,采用高压微射流技术与逐层沉积技术(LBL)制备负载DHA的亚麻籽胶(FG,质量分数为0.4%)-紫苏分离蛋白(PPI,质量分数为0.225%)双层乳液,研究Ca^(2+)添加量(0%~0.5%)对上述双层乳液体系稳定性的影响;同时,采用INFOGEST体外模拟消化模型,探究PPI-DHA藻油单层乳液、FG-PPI-DHA藻油双层乳液、Ca^(2+)-FG-PPI-DHA藻油双层乳液中DHA的消化特性,以及上述3种体系递送虾青素的效率,并通过监测其在消化过程中粒径分布、电荷特性及微观状态变化等解释其内在机理。结果表明:DHA藻油双层乳液储藏20 d后,未添加Ca^(2+)的双层乳液的粒径从10.4μm降低至4.3μm,Zeta-电位从-23 mV降低至-33 mV,Ca^(2+)添加量为0.4%的双层乳液的粒径和电位未发生显著变化,乳液液滴分布均匀,无分层、絮凝、沉淀现象;DHA藻油双层乳液储藏20 d后,添加Ca^(2+)的双层乳液的Turbiscan抗重力稳定性指数(TSI)较未添加Ca^(2+)的双层乳液有明显改善;3种乳液体系模拟消化过程中,游离脂肪酸释放量分别为68.88%、50.84%、52.32%,虾青素生物可及性分别为47.42%、12.54%、9.66%。说明添加Ca^(2+)有利于DHA藻油双层乳液的稳定储藏,但对消化过程中脂肪酸与虾青素的释放具有一定迟缓效果,研究结果可为设计靶向递送体系提供重要理论依据。