蔬菜农药残留检测中酶抑制法的应用分析

目的:探讨酶抑制法在蔬菜农药残留检测中的作用。方法:完成样品与对照溶液的制备后,采用乙酰胆碱酯酶对样品与对照溶液内残留的有机磷和氨基甲酸酯类农药进行检测。结果:白菜样品中对酶抑制率为71.2%;番茄样品对酶抑制率为89.2%;甘兰样品对酶抑制率为90.1%。根据酶抑制程度,表明3种样品中皆含有一定的农药残留。结论:运用酶抑制法能够快速测定蔬菜农药残留含量,但为了保障测定结果的准确性,应结合定性定量方式一同进行检测。     

高通量酶抑制法快速测定蔬菜中有机磷和氨基甲酸酯类农药残留

目的 建立一种室温下高通量酶抑制法快速测定蔬菜中农药残留的方法。方法 从酶抑制法检测原理出发, 以阳性蔬菜样品为研究对象, 通过对提取剂、提取时间及反应体系的选择和优化, 确立酶反应体系。采用该方法检测市售蔬菜样品, 对筛选出阳性样品进行定量检测复核, 验证方法有效性。结果 蔬菜样品用乙腈作为提取液, 采用超声提取, 上清液氮吹后加入磷酸盐缓冲溶液(pH 8.0)作为最终样液, 农药提取效率最高, 且不会对酶抑制法反应体系造成影响。采用优化后的高通量农药速测方法, 以室温(25±5)℃下酶抑制率≥40%作为阳性判定标准, 对筛选出的734个阳性样品进行仪器定量分析复核, 检出符合率达到92.1%。结论 该方法有效提升了农药提取效率和检测效率, 可有效用于蔬菜中有机磷和氨基甲酸酯类农药残留的快速检测。     

湛江四种市售蔬菜农药残留的监测分析及洗涤方法对农残的影响

本文以湛江市售蔬菜为原料,采用随机与定点抽样的办法,采集上海青、生菜、菜心、油麦菜4个品种共80份样品,通过乙酰胆碱酯酶抑制法,按照GB/T5009.199-2003方法进行蔬菜中有机磷和氨基甲酸酯类农药残留的检测,考察不同蔬菜中有机磷和氨基甲酸酯类农药的残留情况,并对数据进行整理分析。然后以菜心和油麦菜为原材料,考察清水、盐水、淘米水和食用小苏打洗涤四种洗涤方法对酶抑制率和农药残留去除率的影响。实验结果表明:样品有机磷和氨基甲酸脂类农残检出率为100%,其中有3个样品超标,超标率为0.094%,且超标样品均为上海青。四种洗涤方法对农残均有不同程度的去除作用,农残去除率为9.91%至96.26%。其中盐水洗涤对农残的去除效果最佳,油麦菜和菜心中农残的最佳去除方法均为10‰盐水浸泡20 min。     

一种商品化酶抑制-比色法快速检测农药残留试剂盒对10种有机磷农药的敏感性测定

目的了解酶抑制-比色法快速检测试剂盒对不同农药的敏感性。方法通过使用一种商品化酶抑制-比色法试剂盒对敌敌畏等10种农药残留分别迚行5个浓度的测定,用抑制率和农药浓度的常用对数拟合回归曲线,同时计算对应的IC50和IC10。结果商品化的酶抑制-比色法试剂盒不是对所有的有机磷农药都敏感,即不是蔬菜中的所有的有机磷农药用酶抑制法都可以测定出来;该试剂盒对10种农药残留的敏感性依照敌敌畏、敌百虫、辛硫磷、喹硫磷、巴胺磷的顺序依次降低;试剂盒对地虫磷、杀螟硫磷、乐果、甲基嘧啶磷、倍硫磷不敏感,该试剂盒对含有浓度为3mg/kg以下的这些农药的样品没有响应。结论建议在日常检测中只要抑制率高于10%的样品建议复检,同时使用色谱、质谱定性定量。     

驴血清胆碱酯酶抑制法快速检测蔬菜中农药残留

采用驴血清丁酰胆碱酯酶作为酶源,对不同的有机磷农药的检测条件和方法进行了研究,同时通过酶抑制法对锦州地区的部分蔬菜进行了农药残留检测.结果表明:乐果、敌百虫、敌敌畏、马拉硫磷对驴血清丁酰胆碱酯酶(BChE)的IC50分别为0.094、0.179、0.124、0.0078mg/mL,驴血清BChE对这4种有机磷农药灵敏度的大小顺序为:马拉硫磷＞乐果＞敌敌畏＞敌百虫 乐果、敌敌畏对丁酰胆碱酯酶的最佳抑制时间为15 min;敌百虫、马拉硫磷对丁酰胆碱酯酶的最佳抑制时间为20min 用酶抑制法检测3个农贸市场的蔬菜样品,发现韭菜有2例检测结果超标,油菜有1例检测结果超标,尖椒有2例检测结果超标;蔬菜样品合格率为86.1％.     

麦麸酯酶抑制法检测辛辣蔬菜假阳性消除的研究

利用酶抑制法可以快速检测蔬菜中的有机磷和氨基甲酸酯类农药残留,这两者能够抑制酯酶的活性,而辛辣蔬菜中含有影响酶活性的含硫化合物,容易导致检测结果出现假阳性。为了消除辛辣蔬菜造成的假阳性,以酶活性抑制率为指标,采用不同的加热方式、时间对4种辛辣蔬菜进行前处理。结果表明,对样品提取液使用水浴加热可起到消除假阳性的作用,其中香葱、洋葱、大蒜和青椒的最佳水浴加热温度分别为80、90、80、80℃,经过处理后的样品提取液对麦麸酯酶的抑制率分别由原来的37.06%、9.65%、17.02%、50.34%下降到12.69%、2.95%、5.79%、33.61%。除青椒外,该方法可在一定程度上消除或大大降低植物酯酶抑制法中假阳性的影响,且不会造成农药残留的损失,从而提高酶抑制法对辛辣蔬菜快速检测的准确性。     

不同前处理对植物酯酶抑制法检测蔬菜中有机磷及氨基甲酸酯类农药残留的影响

利用酶抑制法可以快速检测蔬菜中的有机磷和氨基甲酸酯类农药残留,这两类农药能抑制酯酶的活性,并影响酯酶对底物的催化能力。根据这一原理,采用麦麸酯酶作为酶源对酶抑制法快速检测农残前处理方法中农残提取液、提取方法、提取时间及样品提取液的处理方式进行优化。结果表明:用5%丙酮-磷酸盐缓冲液作为提取液,然后超声提取5 min后,将样品提取液再用0.45μm有机滤膜过滤后蔬菜中农药残留提取量可达到最高;且样品加标回收率为83.61%~102.81%,变异系数为1.20%~7.23%。因此,该前处理方法可满足于麦麸酯酶抑制法快速检测农药残留的需要。     

2018年石家庄市蔬菜中农药残留及慢性膳食暴露评估

目的 了解河北省石家庄市蔬菜中农药残留现状,评估蔬菜中农药残留的慢性膳食暴露风险。方法 随机采集2018年石家庄市主要蔬菜生产基地和集贸市场的蔬菜样品,采用NY/T761-2008方法检测3521批次14类蔬菜样品中的65种农药残留,分析石家庄市蔬菜中农药残留现状,并结合我国居民的蔬菜消费情况和食品安全指数对石家庄市居民于蔬菜中摄入的农药风险进行慢性膳食暴露评估。结果 石家庄市抽检的蔬菜中农药残留检测合格率达99.80%,14类蔬菜样品中检出8类、超标1类,检出率为3.10%,超标率0.20%,超标均为叶菜类蔬菜。定量检测出13种农药,超标农药为水胺硫磷和毒死蜱,分别超标5批次和2批次。对所有检出农药进行慢性膳食暴露评估结果表明,水胺硫磷和毒死蜱的日摄入量相对较高,所有检出农药的食品安全指数值均小于1。结论 石家庄市市蔬菜中农药残留量的安全风险均在安全范围内,居民蔬菜中农药残留的慢性膳食暴露风险小,水胺硫磷、毒死蜱是潜在的风险因子,应重点防患其残留风险。     

2009年大连市部分食品中化学污染物监测分析

目的了解大连市部分食品中重金属、有机磷及氨基甲酸酯农药残留、有机氯及菊酯农药残留以及环己基氨基磺酸钠的污染现状,对食品安全进行有效控制。方法按GB/T 5009—2003《食品卫生检验方法理化部分》检测铅、镉、汞、有机氯及菊酯农药残留、环己基氨基磺酸钠、有机磷及氨基甲酸酯农药残留。结果 39份样品中铅超标5份;镉和汞无超标样品。50份蔬菜样品中检出毒死蜱农药残留1份,超标1份;氯氰菊酯农药残留2份,超标1份。10份茶叶样品中检出联苯菊酯农药残留1份,无超标样品。有机磷及氨基甲酸酯农药、有机氯及菊酯农药、环己基氨基磺酸钠均无检出。结论大连市部分水产品中铅含量较高,污染较明显。需要进一步加强监测,控制污染。农药残留水平较低,只在个别蔬菜和茶叶中有不同程度的检出。     

商品化农残速测试剂盒对5种农药的敏感性测定

该试验旨在探讨6种商品化农残速测试剂盒对5种氨基甲酸酯类农药的敏感性。使用6种商品化酶抑制法快速检测农药残留的试剂盒对涕灭威等5种氨基甲酸酯类农药进行5个浓度水平的测定,用抑制率与农药浓度的对数进行线性模拟回归,计算半抑制浓度IC50和IC10,以此比较各种试剂盒对各种农药的灵敏度和检出限。结果显示:6种试剂盒的抑制率与农药浓度的对数之间存在良好的线性关系,但是每一种试剂盒对这5种农药的敏感性均不相同,6种试剂盒对同一种农药的敏感性也不一样;测试时取用3 mL提取液和取用2.5 mL提取液根据农药的不同和试剂盒的不同存在一定的差异。由于酶抑制法快速检测农药残留的试剂盒对各种农药的检测敏感性不同,且酶抑制-比色法快速检测农药残留的方法是既非定量也非定性的检测方法,所以在实际的检测工作中建议对抑制率≥10%的样品进行复检,同时上色谱质谱进行定性定量。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status