Objective:With the improvement of living standards, consumers are paying more and more attention to the quality of rice. Traditional rice quality detection relies on human sensory judgment, which is inaccurate and inefficient. With the continuous development of molecular imaging technology, more and more scholars at home and abroad have begun to pay attention to its application in the nondestructive testing of agricultural products. Molecular imaging technology combines the advantages of spectral technology and image technology, which can achieve rapid, nondestructive and accurate detection of rice quality. In this paper, taking rice as the research object, we carried out nondestructive detection research on rice varieties, moisture and starch content using molecular imaging technology. We proposed a rapid detection method based on molecular imaging technology for rice variety identification, moisture content and starch content. Molecular images of the rice samples from four origins were obtained using a molecular imaging system, the regions of interest of the rice were identified and, spectral data, textural features and morphological features of the rice were extracted. Spectral, textural and morphological features were selected by principal component analysis (PCA), and nine feature wavelengths were obtained and an optimal model was established with an accuracy of 91.67%, which demonstrated the feasibility of molecular imaging. By comparing the models, the BCC-LS-SVR model based on the RB function had the highest accuracy with R2 of 0.989, RMSEP of 0.767%, R2 of 0.985, and RMSEC of 0.591%. Moreover, starchy rice was detected using molecular imaging. The PCA-SVR model based on the RBF kernel function had the highest accuracy with R2 of 0.989, RMSEC of 0.445%, R2 of 0.991, and RMSEP of 0.669%. Our models demonstrated high accuracy in identifying rice varieties, as well as quantifying moisture and starch content, showcasing the feasibility of molecular imaging technology in rice quality assessment. This research offers a rapid, nondestructive, and accurate method for rice quality assessment, promising significant benefits for agricultural producers and consumers.

The dual-frequency ultrasound-assisted enzymatic digestion (DUED) technique was developed for synchronous green extraction of five heavy metal ions in root vegetables. The combination of alpha-amylase, cellulase, and papain showed significant advantageous in extracting heavy metal ions. Under optimized dual-frequency ultrasonic conditions, the extraction rates of Cr, As, Cd, Pb, and Hg in carrots reached 99.04%, 105.88%, 104.65%, 104.10%, and 103.13% respectively. And the extraction process is highly efficient, completing in just 15 min. Compared to conventional microwave-assisted acid hydrolysis method, this technique eliminates the need for high-temperature concentrated acid, enhancing its environmental sustainability while maintaining mild reaction conditions, making it ideal for biosensors application. Additionally, simultaneous extraction and detection of four heavy metals in lotus roots were successfully achieved by using DUED and a fluorescent paper-based microfluidic chip. The obtained results are consistent with those obtained using conventional methods.

A novel molecularly imprinted nanomaterial (Eu (BTC)-MPS@MIP) was synthesized on the surface of silanized europium-based metal–organic frameworks (Eu (BTC)-MPS) using 1, 3, 5-benzotrioic acid (H3BTC) as a ligand. The resulting Eu (BTC)-MPS@MIP was applied to constructing a smartphone sensing platform for the sensitive and selective detection of clothianidin (CLT) in vegetables. The synthesized Eu (BTC)-MPS@MIP demonstrated the successful formation of a typical core–shell structure featuring a shell thickness of approximately 70 − 80 nm. The developed sensing platform based on Eu (BTC)-MPS@MIP exhibited sensitivity in CLT detection with a detection limit of 4 µg/L and a linear response in the range 0.01 − 10 mg/L at excitation and emission wavelengths of 365 nm and 617 nm, respectively. The fluorescence sensing platform displayed excellent specificity for CLT detection, as evidenced by a high imprinting factor of 3.1. This specificity is primarily attributed to the recognition sites in the molecularly imprinted polymer (MIP) layer. When applied to spiked vegetable samples, the recovery of CLT ranged from 78.9 to 102.0

水产品是人类摄入重金属的重要来源之一.为检测上海市常见养殖水产品的重金属残留及其污染来源,并进行膳食风险评估,文章采用快速消解-电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS)测定水产品及其养殖环境中铅、镉、铬、汞、砷的含量;并使用单因子指数(single factor pollution index,Pi)、重金属污染指数(metal pollution index,MPI)、相关性分析和危害商数(hazard quotient,HQ)对水产品的金属残留现状、污染来源、膳食风险进行评估.结果表明,重金属污染程度依次为:蟹类>虾类>鱼类、青鱼>鲢鱼>鳙鱼>草鱼、底泥>饲料>养殖水.Pi结果显示,虽然饲料中的Cr、Pb、Cd超出了限量标准,但所有样品的污染均不明显.相关性分析结果显示,水产与饲料中Cr含量之间存在明显的相关性,与其他4种重金属不具相关性.膳食风险评估结果显示,水产品中5种重金属的HQ值均小于1,因此可认为摄入鱼类、甲壳类水产品不会给暴露人群带来明显的健康风险.

河豚因其独特的鲜美口感深受消费者喜爱,随着我国食用养殖河豚市场的逐渐放开,更多消费者有机会品尝这一美食.本文选择我国河豚中有代表性的品种暗纹东方鲀,对其基本营养成分、氨基酸、脂肪酸和风味物质的研究现状进行了阐述,同时介绍了养殖模式对暗纹东方鲀营养品质的影响和相关探索性研究进展,并在此基础上对暗纹东方鲀的未来研究方向进行了展望.

Hen eggs are one of the most popular foods worldwide, and their safety is critical. Employing 16S rRNA full-length sequencing is an effective way to identify microorganisms on or in eggs. Here, hen eggs collected from poultry farms over four seasons, as well as from markets in Shanghai, were analyzed with third-generation sequencing. Firmicutes (44.46%) and Proteobacteria (35.78%) were the two dominant phyla, and Staphylococcus, Acinetobacter, Aerococcus, Psychrobacter, and Lactobacillus were the dominant genera. The dominant genera on the eggshell surfaces from the farms varied with the seasons, and the highest contamination of Staphylococcus (32.93%) was seen in the eggs collected during the summer. For the market samples, Pseudomonas was the most abundant in content, with Staphylococcus being the most-often genera found on the eggshell surfaces. Moreover, several potential pathogenic bacteria including Riemerella anatipestifer (species), Klebsiella (genus), and Escherichia/shigella (genus) were detected in the samples. The results revealed the impacts of weather on the microbiota deposited on an eggshell’s surface, as well as the impacts due to the differences between the contents and the surface. The results can help disinfect eggs and guide antibiotic selection.

Herein, A ratiometric fluorescent sensor based on molecularly imprinted multilevel mesoporous silica (MIFP-SiCQDs@CdTe QDs) was designed for highly sensitive detection of imidacloprid (IDP) pesticide with long half-life in soil, plants, and water environments. In this sensor, CdTe QDs were anchored onto the multilevel mesoporous of MIFP-SiCQDs by post-imprinting modification as the analytical signal to improve the detection sensitivity of the conventional doping method (d-MIFP). The results showed that the synthesized MIFP-SiCQDs@CdTe QDs possessed both small mesopore (2-3 nm) and large mesopore (5-50 nm), which is favorable for the anchoring of CdTe QDs (about 2-3 nm in diameter) and the mass transfer of IDP into them. Due to the multilevel mesoporous structure and low background, the sensor responded well to the addition of IDP in the range of 5 ng mL-1-0.5 mu g mL-1 with a detection limit of 3.55 ng mL-1. The MIFP-SiCQDs@CdTe QDs sensor was successfully applied to determine IDP levels in real samples with the average recovery ranging from 97.64 to 109.88% and RSD values ranging from 1.00 to 4.65%. Furthermore, the quenching mechanism of MIFP-SiCQDs@CdTe QDs by IDP was considered to be the dynamic quenching. These results proved that the construction of multilevel mesoporous and post-imprinting modification of the analytical signal is an effective method to improve the sensitivity of d-MIP.

In this study, a novel fluorescent immunochromatographic assay (ICA) strip based on quantum dot encoded multicolour nanobead (QB) was developed to detect three neonicotinoid insecticides in the vegetable samples simultaneously. The results showed that three QBs with red-, yellow- and green-emitting were successfully synthesized by embedding different ratios of two kinds of hydrophobic CdSe/ZnS QDs (lambda(em) = 565 nm and lambda(em) = 620 nm) into the polymer matrix. The obtained three QBs were further used to label the monoclonal antibodies (mAbs) specific to imidacloprid (IMI), clothianidin (CLT) and thiamethoxam (TMX). The resultant QB@mAbs nanoprobes, including QB(red)@IMI mAbs, QB(yellow)@CLT mAbs and QB(green)@TMX mAbs, presented excellent monodispersity with distinguishable emission colours. Furthermore, the fabricated QB-ICA strip based on QB@mAbs nanoprobes achieved a more sensitive simultaneous detection for three neonicotinoids with the detection limits of 14.58 ng/mL for IMI, 0.27 ng/mL for CLT, and 0.36 ng/mL for TMX, respectively. This was better than most of the conventional based enzyme-linked immunosorbent assay (ELISA). Moreover, the QB-based ICA strips also exhibited good stability and specificity for the multiplex detection of IMI, CLT, and TMX. In the spiked Chinese cabbage samples, the recovery of IMI, CLT, and TMX ranged from 72.08% to 98.70%, with RSD values ranging from 3.60% to 13.09%. In brief, the great performance of the developed QB-ICA approach demonstrates its potential for simultaneous and quantitative neonicotinoids detection in agricultural products.

In this work, the inhibition of clustered regularly interspaced short palindromic repeats (CRISPR) - CRISPR associated protein (Cas) trans-cleavage by Pb2+-induced G-quadruplex has been firstly explored to detect Pb2+ in tea beverage and milk. In absence of Pb2+, the Na+-induced G-quadruplex can be cleaved by CRISPR-Cas12a. In contrast, Pb2+ can competitively combine with G-quadruplex, resulting in its conformational changes and resistance to trans-cleavage of CRISPR-Cas12a. Therefore, the fluorescence resonance energy transfer can happen. Pb2+ can be detected in a linear range from 100 nM to 5 mu M with a lowest detection limit of 2.6 nM and a relative standard deviation of 4.32%. In summary, this work not only provides a new method for Pb2+ detection based on its induced G-quadruplex inhibition on CRISPR-Cas12a trans-cleavage, but also broadens the application of CRISPR-Cas system for heavy metal analysis in the field of food safety.

乳铁蛋白(Lactoferrin,LF)是一种重要的铁离子结合蛋白,因其在抗菌杀菌、抗病毒及调节机体免疫方面效果显著,近年来被广泛应用于食品领域.试验旨在建立LF双抗体夹心法检测方法.试验以乳铁蛋白为抗原免疫BALB/c小鼠,应用常规的细胞融合技术获得18株杂交瘤细胞株,进而获得腹水抗体18个,效价测定结果显示13株单克隆抗体的效价均在1:2.56×105以上;用效价测定较高的13株抗体作为包被抗体,用辣根过氧化物酶标记过的多克隆抗体作为酶标抗体,经过配对筛选,8号单克隆抗体作为包被抗体,命名为FL8,建立牛乳铁蛋白的双抗体夹心ELISA检测方法,最低检测限为0.05 ng/mL,最适检测范围为0.05～3.2 ng/mL.

通过采用QuEChERS前处理技术,将样品经乙腈超声提取,加入沉淀剂沉淀,离心后取上清液,再通过添加吸附剂净化,供高效液相色谱-串联质谱法分析,建立了一种能同时检测生鲜乳中7种巴比妥类药物的高效液相色谱-串联质谱法.经验证,采用该方法,7种巴比妥类药物在2～ 100 ng/mL浓度范围内均呈现出良好的线性关系,相关系数大于0.9950,该方法检出限为10μg/kg,回收率为79.9％～ 99.5％,回收率试验变异系数≤7.58％,重复性试验变异系数≤4.41％.表明该方法能快速检测生鲜乳中7种巴比妥类药物,检测结果的准确度和灵敏度均较高,可做到批量测定,具有较好的应用前景.

A novel rapid and cost-effective pre-processing method for the simultaneous determination of pyrethroid pesticides in vegetables has been developed and validated. The process of pesticide extraction was carried out by the QuEChERS (quick, easy, cheap, effective, rugged and safe) method combined with filtration by filter paper, and cleanup was carried out by the multi-plug-filtration-cleanup (m-PFC) method with no centrifuge program during the whole process. The pre-processing method is optimized for gas chromatography (GC). The process is convenient and time saving, requiring just a few seconds per sample. The recovery rate (70–120%), limit of detection (0.0001–0.007 mg/kg), precision (0.2–9.3%) and accuracy for each analyte were determined in 10 representative vegetables with good results. Finally, the feasibility of the developed method was further confirmed by the successful determination of pyrethroid-pesticide residues in pyrethroid-containing practical samples within the processing method coupled with thin-layer chromatography and a colloidal-gold test strip.

作者首先修饰和制备了对啶虫脒农药有特异响应的硅碳量子点(SiCDs),并以此作为荧光探针开发了可快速检测啶虫脒农药的高灵敏分子印迹荧光传感器SiCDs@MIPs,同时研究了模板与功能单体物质的量比、交联剂添加量、SiCDs包埋量对SiCDs@MIPs检测灵敏度的影响.结果表明,SiCDs@MIPs的最适制备条件为:模板与功能单体的物质的量比为1:4,交联剂添加量为25 μL,SiCDs包埋量为10 mg.在最优检测条件下,SiCDs@MIPs对啶虫脒的检出限为0.086 Nmol/L,线性范围为0.045-0.450 μmol/L,相关系数为0.989,检测时间仅需25 min.进一步将制备的SiCDs@MIPs应用于白菜、番茄和冬瓜中啶虫脒农药残留的检测,回收率可达到73.0％～109.0％.该方法为蔬菜中啶虫脒农药残留的检测提供了新策略.

建立了气相色谱-四极杆/飞行时间质谱法测定葡萄中农药残留的非靶向快速筛查分析方法.样品用乙腈超声提取,加入复合沉淀剂,振荡离心,得到提取液.提取液经净化柱净化后过滤膜,用气相色谱-四极杆/飞行时间质谱(GC-Q-TOF/MS)进行分析测定.结果表明,葡萄中75种农药化合物在0.3、0.6、1.5 mg/kg加标水平下,回收率为60.9％～104.4％,相对标准偏差(RSD)为0.2％～26.3％(n=6);在0.04～2.00μg/mL质量浓度范围内呈良好的线性关系,线性相关系数(R2)均大于0.99;方法检出限(LOD)为0.08 mg/kg,方法定量限(LOQ)为0.24 mg/kg.该方法操作简便、灵敏度较高,准确度与精密度均能达到定量分析要求,适用于葡萄中农药多残留非靶向快速筛查.

A novel electrochemical paper-based microfluidic chip was firstly developed to simultaneously detect cadmium (II) and lead (II) in vegetable and fruit samples. The patterned filter paper was prepared through the printing of three-electrode patterns on filter paper using an automatic screen-printing machine. Portable and low-cost (less than $1) electrochemical paper-based chips are prepared by filling conductive ink and hot pressing. The paperbased chip could realize signal amplification through gold nanoparticles and seed solutions. Cadmium (II) and lead (II) were sensitively detected by their aptamers labeled with methylene blue and ferrocene, separately. Under the optimal experimental parameters, the paper-based chip detected cadmium (II) and lead (II) as low as 23.31 and 46.23 pmol/L (3 sigma) with a wide linear range from 0.1 to 1000 nmol/L and exhibited excellent selectivity. The RSD was 6.41% (cadmium (II)) and 4.20% (lead (II)). Compared with other methods, the paperbased chip could complete the detection within 15 min and could be stored at -20 degrees C for 5 days. Furthermore, the results for vegetable and fruit samples were agreed with the results of the graphite furnace atomic absorption spectrophotometer, in which the recovery rates were 93.20%-95.80%.

本文在分析无土栽培分类及优缺点的基础上,从文献研究和现有标准两方面系统总结国内外发展现状,并提出通过制定相关标准、加强政策补贴及监管等措施推动无土栽培产业的发展.

为考察和了解上海地区奶牛场养殖状况和生乳安全生产情况,本研究通过实地走访和问卷调查方式,对24家有代表性的规模养殖场(小区)进行了养殖情况(养殖区域、日产奶总量、存栏总量、产奶牛存栏数等)、环境条件(饮用水、挤奶场地、挤奶用具、挤奶消毒方式、饲料等)、疫病防控情况(疫苗使用、给药情况、耐药性监测、乳腺炎情况、药物使用及疗效等)进行调查,初步掌握了上海市主要奶牛场的养殖情况和生乳安全生产状况,并针对存在的问题提出开展奶牛场养殖环境治理及推广安全生产的对策和意见.

为了解冷鲜鸡的货架期,以挥发性盐基氮(TVB-N)为品质表征参数,研究了冷鲜鸡在不同温度(5、10和15℃)下的变化规律,利用Arrhenius方程建立了不同温度下冷鲜鸡货架期预测模型,并对该模型进行内部验证和实际样本验证.结果表明:Arrhenius方程中TVB-N的活化能Ea为52.636 kJ/mol,指前因子ko为3.8×107.以5、10和15℃作为验证温度,其相对误差为6.30％,6.00％和3.91％,实际样本验证最大相对误差为-10.5％,说明该模型拟合效果好.通过该模型可快速获得不同贮藏温度下冷鲜鸡的货架期,为生产企业和监管部门制定货架期标准提供理论依据.

为了解上海市生乳中肺炎克雷伯氏菌污染水平,分析本市乳制品中肺炎克雷伯氏菌污染风险来源及耐药情况,本研究对上海市乳品加工厂的生乳样本和养殖场环境样本进行了肺炎克雷伯氏菌计数和细菌分离鉴定,并对分离菌株开展毒力基因检测和耐药性分析.结果显示,上海市健康奶牛中肺炎克雷伯氏菌分离率为11.25％,远低于患乳房炎奶牛样品检出率;环境溯源样品中肺炎克雷伯氏菌检出率为21.3％,多在垫料及土壤中检出;对80家奶牛场未患乳房炎奶牛样品和47批次环境溯源样品细菌分离结果均表明,夏季肺炎克雷伯氏菌检出率显著高于冬季;本市分离的肺炎克雷伯氏菌,对β-内酰胺类和氨基糖苷类药物存在普遍耐药,且多重耐药性十分严重,耐药菌株占比达98.5％;分离菌株中毒力基因mrkD、fimH、wabG的检出率分别为88.89％、66.67％、33.33％,rmpA未检出.以上结果表明,夏季为肺炎克雷伯氏菌高发季节,且主要的外部污染风险为垫料和土壤,毒力基因检测表明,菌株不具备高致病性,多为呼吸道和消化道常在菌.通过本研究,提示居民不宜直接饮用生乳,养殖场应加强养殖环境、挤奶及生产运输环节的卫生管理,不滥用抗生素.

目的 建立分子印迹固相萃取-超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)检测牛奶中11种氨基糖苷类抗生素(巴龙霉素、妥布霉素、庆大霉素、卡那霉素、阿米卡星、安普霉素、链霉素、双氢链霉素、新霉素、壮观霉素、潮霉素B)残留的测定方法.方法 样品经5％三氯乙酸-乙腈提取,氨基糖苷类分子印迹聚合物(molecular imprinted polymers,MIPs)固相萃取柱净化,SiELC Obelisc R色谱柱分离,采用超高效液相色谱-串联质谱仪进行测定.结果 方法检出限为1.0～5.0 μg/kg,定量限为2.0～10.0 μg/kg.11种氨基糖苷类药物在1.0～500.0 μg/kg范围内关系良好(r2≥0.9911),牛奶中加标回收率为70.7％～115.6％,相对标准偏差(relative standard deviations,RSDs)(n=6)为1.1％～9.8％.结论 本方法准确度、灵敏度高,可用于牛奶中11种氨基糖苷类抗生素的同时检测.