我国与主要贸易国家间猪肉中农药残留限量对比分析

掌握不同国家、地区猪肉中农药最大残留限量（Maximum Residue Limits，MRL）要求现状，分析其差异性，以便降低猪肉贸易风险。收集我国和主要贸易国家，联合国粮农组织食品法典委员会（Codex Alimentarius Commission，CAC）、澳大利亚、美国、日本、新西兰、欧盟现行的猪肉农药MRLs标准和技术法规进行对比分析。由于各国饮食习惯、膳食结构不同，我国与主要贸易国家之间存在农药MRL差异，主要表现在：部分农药残留物的定义中所包含的农药转化物、代谢物、反应产物等的不同；农药最大残留限量指标数量和品种的不同，其中我国与欧盟、日本和澳大利亚等国在指标数量上差异较大；相同农药残留限量指标的宽严程度不同，个别指标差异较大。我国应继续加强国际间猪肉农药残留限量标准制定交流，进一步完善我国猪肉农药残留限量标准体系。     

超声辅助提取-氢化物原子荧光光谱法测定香辛料中的铅

建立了一种操作简单、快速、高灵敏度、高提取效率的超声辅助提取-氢化物发生-原子荧光光谱法测定香辛料中铅的分析方法。考察了提取液的酸度、超声温度和时间对提取效率的影响,最终确定1.5%的硝酸为提取溶剂,超声时间和温度分别为60 min,40℃。考察了载流酸度、铁氰化钾浓度对铅测定时荧光值和线性系数的影响。实验表明铅含量在0~20μg/L范围内线性关系良好,线性相关系数大于0.999,检出限为2.6μg/kg,相对标准偏差为1.59%~3.52%,加标回收率为98.3%~108.3%,适用于香辛料中铅含量的检测。     

基于HPLC-MS/MS法的咽炎片中麦冬掺伪检查

目的 建立咽炎片中麦冬掺伪检测方法.方法 高效液相色谱-串联电喷雾三重四级杆质谱法(HPLC-MS/MS),采用Innoval ODS-2色谱柱(2.1 mm×100 mm,3μm),以乙腈-0.1％甲酸(75:25)为流动相,流速为0.3 ml/min,柱温40℃,进样量2μl,多反应监测(MRM)模式.结果 31批...     

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.     

高效液相色谱法测定虫草胶囊中腺苷的含量

目的建立高效液相色谱法(high performance liquid chromatography,HPLC)测定虫草胶囊中腺苷的含量。方法样品经过研碎、超声处理、离心、过滤后上机待测。使用岛津VP-ODS(250 mm×4.6 mm,5μm)色谱柱,以甲醇-0.04 mol/L磷酸二氢钾(15:85,V:V)为流动相;流速:1.0 m L/min;进样量:10μL;检测波长为262 nm。结果腺苷在0.7~70μg/m L的范围内呈良好线性关系,r=0.9999,回收率为99.1%~99.5%,相对标准偏差为0.2%~0.6%。结论本研究建立的方法简便、快捷、准确,可准确测定虫草胶囊中腺苷的含量。     

纤细裸藻β-1,3-葡聚糖异养发酵与生理功效的研究进展

纤细裸藻是我国于2013年批准的新资源食品,纤细裸藻具有极高的营养价值,含有氨基酸组成合理的蛋白质、具有特殊生理功效的β-1,3-葡聚糖三螺旋晶体、维生素E中活性最强的同分异构体α-生育酚、多不饱和脂肪酸、矿物质等。该文首先从纤细裸藻异养发酵条件因子优化与培养基质代谢机制两个方面研究进行归纳;其次对裸藻β-1,3-葡聚糖的发酵制备、纯化、结构分析等进行了介绍;最后从促进免疫力、抗病毒、抑制肿瘤等方面归纳了裸藻β-1,3-葡聚糖生理功效方面的研究进展。旨在为裸藻异养发酵的应用研究与基质代谢基础研究提供理论支持;为裸藻β-1,3-葡聚糖在食品、药物、化妆品、新材料等领域的开发应用提供支持。     

氢氧化钡处理-分散液液微萃取结合气相色谱-串联质谱法测定肉制品中9种N-亚硝胺

目的 建立氢氧化钡碱溶液-分散液液微萃取结合气相色谱-串联质谱法(gaschromatography-tandem massspectrometry,GC-MS/MS)同时测定肉制品中9种N-亚硝胺类化合物的分析方法。方法 肉制品样品在80℃水浴中经氢氧化钡碱溶液皂化,去除油脂干扰,进一步将N-亚硝胺提取到水溶液中,再加入甲醇(分散剂)和二氯甲烷(萃取剂)进行高效萃取富集,在多反应监测模式下分析,稳定同位素内标法定量。对影响萃取效率的因素进行考察,如样品提取步骤中的皂化条件,无机盐、萃取剂和分散剂的种类及体积等。通过优化色谱、质谱参数和前处理条件,获得最佳检测结果。结果 除了N-亚硝基二甲胺(N-nitrosodimethylamine, NDMA)的线性范围为2.5～50.0 ng,其他8种N-亚硝胺类化合物在1.0～50.0 ng范围内线性关系良好, 9种N-亚硝胺类化合物的相关系数(r2)范围为0.9954～0.9999,方法检出限和定量限分别为0.1～0.2μg/kg和0.2～0.5μg/kg。在火腿、五香鸡肉和牛肉样品中分别进行0.5、5.0μg/kg浓度水平的加标实验,所有...     

QuEChERS/超高效液相色谱-串联质谱法测定大黄鱼中非法染料硫代黄素

建立了超高效液相色谱-串联质谱法测定大黄鱼中硫代黄素残留的分析方法.样品中的硫代黄素经乙腈-水溶液提取,QuEChERS方法净化,C18色谱柱分离,以0.1％(体积分数)甲酸水溶液-乙腈为流动相进行梯度洗脱,三重四极杆质谱电喷雾多反应监测模式检测,外标法定量.结果表明,硫代黄素为0.5～50.0 ng/mL时线性关系良...     

自动电位滴定仪测定饼干中酸价和过氧化值的应用研究

目的建立自动电位滴定仪法测定饼干食品中酸价和过氧化值的检测方法。方法通过石油醚超声浸提提取饼干样品中的油脂,分别用自动电位滴定仪法和人工滴定法测定样品中的酸价和过氧化值。结果取15份饼干样品分别用自动电位滴定仪和人工滴定测定酸价和过氧化值,将结果进行配对t检验,方法无显著差异(P>0.05),人工滴定法测定时高、低酸价值样品相对标准偏差分别为0.34%和6.74%,自动电位滴定仪法测定时对应的相对标准偏差分别为0.27%和1.87%;人工滴定法测定时高、低过氧化值样品相对标准偏差分别为0.13%和0.96%,自动电位滴定仪法测定时对应的相对标准偏差分别为0.08%和0.21%。结论自动电位滴定法测定饼干中酸价和过氧化值所得结果精密度均优于人工滴定法,稳定性好,安全且便于操作。     

Layer-by-layer electrostatic self-assembled coatings based on flaxseed gum and chitosan for Mongolian cheese preservation

Mongolian cheese, a daily essential dairy product of Mongolians, is nutritious but susceptible to microbial contamination. Edible coatings consisted of casein, chitosan and flaxseed gum were developed to extend the shelf life of Mongolian cheese by self-assembly on its surface. Due to the amphoteric properties of casein, positive and negative charges were obtained as a template by adjusting the isoelectric points. With chitosan as the positive charge provider and flaxseed gum as the negative charge provider, edible coatings were formed on the surface of Mongolian cheese by layer-by-layer electrostatic self-assembly technology. Chitosan inhibited the proliferation of internal microorganisms (molds and yeasts) when it was the innermost layer, and resisted the invasion of foreign microorganisms (Escherichia coli and Staphylococcus aureus) while it was the outermost layer. And, this effect became stronger with the increase of layer numbers. The layer-by-layer electrostatic self-assembly technology of polysaccharide not only improved the quality of Mongolian cheese but extended its shelf life.