豇豆中啶虫脒基体标准物质的研制

目的：建立豇豆中啶虫脒基体标准物质的研制方法。方法：将新鲜种植的空白豇豆样品粉碎、冻干、添加、混匀、二次冻干、粉碎、过筛、混匀、包装、Co60辐照灭菌。采用液相色谱—质谱串联方法进行检测,基体标准溶液定量校正。通过均匀性、稳定性检测合格后,采用实验室联合定值的方式进行测量定值。结果：该方法制备的样品易于贮藏、运输和稳定保存,均匀性、稳定性良好,其啶虫脒特性值为(0.283 7±0.008 5) mg/kg(k=2)。结论：试验制备的豇豆中啶虫脒基体标准物质符合国家计量技术规范中均匀性、稳定性要求,准确度良好,能够应用于检测过程中质量控制、分析仪器校准、检测方法确认评估等工作。     

Novel monoclonal antibody-based sensitive enzyme-linked immunosorbent assay and rapid immunochromatographic strip for detecting aflatoxin M1 in milk

Monoclonal antibody (mAb) that is specific to AFM1 was generated from the hybridoma cell line, 10F3C10, which was obtained by the fusion of mouse NS1 myeloma cells with the spleen cells of mouse that had been immunized with AFM1-bovine serum albumin (BSA). The 10F3C10 mAb is belong to the immunoglobulin G1 isotype. Both competitive direct and indirect enzyme-linked immunosorbent assay (ELISA) was utilized to characterize the mAb for AFM1. The concentrations of AFM1, AFB1 and AFG1 that caused 50% inhibition (IC₅₀) of the binding of AFM1-horseradish peroxidase (AFM1-HRP) to the antibody were found to be 0.022, 0.310 and 2.12 ng/mL, respectively. The immunochromatographic strip (immunostrip) assay with mAb-gold nanoparticle conjugates as a detection marker exhibited a visual limit of detection of 0.1 ng/mL for AFM1 and the analysis took a total of 10 min. Closely examining 17 milk-based samples using cdELISA revealed that four were slightly contaminated with AFM1 at concentrations from 0.002 to 0.054 ng/mL. All milk samples were negative in the immunostrip test because the levels of contaminant were below the detection limit of the strip. Notably, the presented cdELISA and immunostrip methods are highly sensitive methods for detecting AFM1 in milk.     

检测实验室中标准物质的质量控制及管理

标准物质是保证准确量值和量值溯源的重要工具,标准物质的有效控制和管理是确保实验室检测数据准确的关键步骤,关系着实验室质量控制水平。对标准物质进行有效的管理控制,充分发挥标准物质的功能,是当前检测实验室急需解决的关键问题。本文主要探究了从标准物质的购买、验收及验证、储存管理、配制、标识、使用、期间核查、失效后处理等全过程进行系统地控制,保证标准物质的质量,确保标准物质在质量控制、校准测量仪器、评价测量分析方法、赋予物质特性量值、考核评价检测人员的技术能力、产品检测过程等方面起到重要作用,从而达到提高检测实验室检测数据的准确性和检测技术能力水平的目的。     

An immunoassay for ochratoxin A without the mycotoxin

Phage display peptide libraries allow the selection of new molecules capable of mimicking the structural and functional features of native proteins or chemicals. This technology can be applied to developing new reagents, which may serve as the surrogate of the original objects. In order to screen peptides capable of mimicking ochratoxin A (OTA) in the interaction with anti-OTA monoclonal antibody (McAb) and establish the immunoassay for OTA, an anti-OTA McAb was used as the target for panning-elution selection from a phage random seven-peptide library. After four rounds of panning, 11 phages were found to be able to mimic OTA in binding with the antibody. Enzyme-linked Immunosorbent Assay (ELISA) for detecting OTA was established with the phages. In the most sensitive assay, the linear range of the inhibition curve was 200–8000 pg/ml; the detection limit was 150 pg/ml. The inserted peptide sequences were deduced by DNA sequencing. The common amino acid residue sequence was IR(V)PMV(L)XX (X is any amino acid residues), which was verified by two synthesized peptides. The results demonstrated that those phage peptides could be used as the surrogate of OTA to establish the immunoassay.     

A validated strip-based lateral flow assay for the confirmation of sheep-specific PCR products for the authentication of meat

Molecular methods, such as PCR and real-time PCR, have been developed to detect species in meat and meat products. Despite good specificity and sensitivity, they are not widely implemented in food control programs due to complex operation or financial reasons. In the present study, a simple, rapid and affordable method, Sheep-PCR-Strip [Sheep specific polymerase chain reaction-Strip], was developed for the authentic identification of raw and heat-treated mutton. The assay is based on PCR amplification of sheep DNA, followed by detection of the PCR product by a strip format; the result can be read within 5 min by the naked eye. There is a real advantage of the strip approach rather in the reduced time (5 min versus electrophoresis) and avoidance of chemicals (e.g. ethidiumbromide). The sensitivity of the Sheep-PCR-Strip test was established to be 0.01% for the detection of adulterated meat; the limit of detection (LOD) was up to 0.01 pg of sheep DNA. The assay was also specific for sheep, and no cross-reactions were observed in other non-target species. It is a promising new tool for sheep identification and can be rapidly modified for other meat detection and widely used for solving problems related to food quality assurance, species authentication and traceability.     

食品安全数据分析可视化模型研究

目的 全面提升食品安全风险的感知、筛查、分级、预警和防控能力, 完善食品安全监管与治理体系, 客观正确的引导舆情。方法 采用大数据分析技术研究食品安全检测数据, 建立食品安全分析可视化模型。运用大数据分析平台Hadoop, 结合Tree Ensemble和Model-Based Ranking算法特征性分析食品抽检数据, 搭建BP神经网络, 结合Apriori和FP-growth关联分析等技术, 深度挖掘相关信息, 有效集成为对食品安全治理体系有价值的信息资源。结果 以折线图、热力地图等可视化模型实现食品类别、检测项目、结果分析、生产地址、检测数据分析及发展趋势等相关信息进行在线展示与分析, 能够满足关注食品安全的各领域人员很直观地就获得自己需要的食品安全信息的需求。结论 可视化模型能够增强数据分析结果的视觉效果和直接性, 切实提高食品安全风险预警的靶向性、有效性。     

Evaluation of pesticide residues in fruits and vegetables from the region of south-eastern Poland

According to the World Health Organization, consumption of fruit and vegetables in Europe constituted over 30% of consumer diet. Fruits and vegetables are good sources of vitamins, minerals, fibre, and antioxidants. Besides their nutrient value, these products can be a source of toxic substances i.e. pesticide residues. The aim of this study was to determine the presence of pesticide residues in Polish fruits and vegetables and to assess if these residues pose a risk to the health of the consumer. Furthermore, compliance with legal regulations concerning the use of plant protection products in crop cultivation was ascertained.In 2010–2012, 1026 unprocessed samples of fruits and vegetables were analysed. Pesticide residues were found in 376 samples (36.6% of tested samples). In 18 samples (1.8%), residues exceeded Maximum Residue Limits. In 28 (2.7%) samples, substances not recommended for a given crop were detected.The highest values of long-term exposure were found for dimethoate residue in apples (1.7% ADI, adults; 6.8% ADI, children). For most detected pesticides, long-term exposures were below the values of 1% ADI for adults and 3% ADI for children.The highest values of short-term exposure were obtained in the case of consumption of apples with azoxystrobin (4.5% ARfD, adults; 13.3% ARfD, children).     

实时荧光环介导等温扩增技术快速检测牛肉中的大肠杆菌O157

目的 建立实时荧光环介导等温扩增技术(real-time fluorescence loop-mediated isothermal amplification, RF-LAMP)快速检测大肠杆菌(Escherichia coli, EHEC)O157的分析方法。方法 针对大肠杆菌O157编码O抗原的rfbE基因设计引物。对该方法进行特异性验证, 同时对大肠杆菌O157:H7纯培养物的灵敏度和人工污染牛肉的检出限进行测定, 对61份牛肉样品进行RF-LAMP检测, 并与GB 4789.36-2016方法进行比较, 评价RF-LAMP方法的敏感性、特异性和准确度。结果 10株大肠杆菌O157呈阳性结果, 21株非大肠杆菌O157呈阴性结果, 该方法特异性良好。纯培养物检测的灵敏度为5.1 CFU/mL, 人工污染的牛肉样品的检出限为5.1 CFU/g。结论 本研究建立的RF-LAMP技术特异性好、灵敏度高、操作简单, 可实时监测扩增反应, 避免了繁琐的电泳过程, 实现了对大肠杆菌O157的快速检测, 对大肠杆菌O157引起的食源性疾病的预防和控制具有重要意义。     

An investigation into the structure,morphology and thermal properties of amylomaize starch-fatty acid complexes prepared at different temperatures

Amylomaize (Hylon VII) starch-fatty acid (capric, myristic, palmitic, stearic, oleic) complexes prepared at 30, 50 or 70 °C were studied using XRD, DSC, SEM, TGA and FTIR techniques. XRD diffractograms displayed the typical V-form of complexed amylose regardless the temperature of preparing the complexes. The degree of crystallinity of the complexes increased while the size of the crystals formed decreased as the preparation temperature of the complexes increased. DSC thermograms showed that the dissociation temperature of the complexes was increased proportionally to the chain length increase of the fatty acid. TGA indicated that oleic acid was adequately protected in the form of complexes. SEM micrographs showed the presence of crystals of the complexes either in the form of spherulites or in the form of lamellae. Enzymatic hydrolysis of the complexes led to quantitative recovery of the guest molecules. Hylon VII proved to be a suitable prospective complexing agent for the production of complexes of lipids.