食品安全与鲜度的检测与监控(上)

简述影响食品安全与鲜度的主要因素及其检测技术。诸如农药残留;抗生素、生长激素、抗寄生虫药物;有害元素(Hg、Pb、Cd、As、Sn、Cu、Cr、Al、Ni、F)以及制假掺假与有毒食品加工等。另一部分为水产品、果蔬食品的鲜度检测方法。     

基于多光谱融合的奶粉掺假诊断方法

发展了一种多光谱融合新技术,该技术充分利用拉曼光谱与红外光谱的互补特性,并借助数据融合手段,高效实现奶粉掺假检测.为进一步提升数据融合算法的准确性,有机结合离散小波变换(DWT)多尺度特性及竞争性自适应重加权偏最小二乘线性判别(CARS-PLSDA)算法,以有效扣除光谱建模中的干扰信息.为验证多光谱融合技术的有效性,对4种典型奶粉掺假体系分别建立分类判别模型.结果表明,基于DWT-CARS-PLSDA多光谱融合算法所建的面粉、淀粉、糊精和大豆分离蛋白奶粉掺假模型灵敏度分别为94.74%、100%、84.21%和100%,正确率分别为99.42%、98.83%、98.25%和98.83%.与单独对拉曼光谱或红外光谱建立模型相比,4种模型能够显著提高奶粉掺假检测灵敏度和准确性,为奶粉掺假快速诊断提供了一种有效工具.     

食品安全与鲜度的检测与监控（下）

简述影响食品安全与鲜度的主要因素及其检测技术。诸如农药残留;抗生素、生长激素、抗寄生虫药物;有害元素（Hg、Pb、Cd、As、Sn、Cu、Cr、Al、Ni、F）以及制假掺假与有毒食品加工等。另一部分为水产品、果蔬食品的鲜度检测方法。     

蛋白类食品新鲜度的检测方法

食品安全的重要性不言而喻,食品新鲜度受到人们的广泛关注,因而研究食品新鲜度的检测方法对保障食品安全有着重要意义。与色谱、光谱和质谱等检测手段相比,传感检测技术具有准确、简便、快捷和成本低等优势,成为食品新鲜度检测的发展趋势。高蛋白质类食物在腐败变质过程中会产生生物胺、挥发性盐基总氮(Total Volatile Basic Nitrogen,TVB-N)、氨气等挥发物和微生物代谢产物,新型传感技术通过检测这些物质的含量实现对食品新鲜度的检测。文章分析介绍了现有的3类传感检测技术(比率荧光型传感技术、生物胺比色传感技术和智能氨气传感器技术)的原理、特点及应用等。     

高通量测序技术在水产品加工贮藏中的应用

目的 通过对水产品加工贮藏过程中微生物群落结构的动态分析,有利于发现腐败菌及病原微生物,以进一步提高水产品的品质,延长其货架期。方法 在介绍高通量测序技术的主要特点和发展历程的基础上,重点阐述高通量测序技术在发酵产品的生产、掺杂掺假的鉴别、食源性病原菌和腐败菌的检测等水产品加工贮藏领域中的应用,分析并解决存在的问题,展望高通量技术的发展前景。结论 随着未来生物工程领域技术水平的不断发展,测序成本低、耗时短、准确度高的测序技术将会逐渐替代传统的检测方式,更好地应用于水产品品质评价和微生物多样性分析中。     

检验食品成份的新技术

据美国《预制食品》报道,鉴定食品中是否掺假是全世界食品加工业都非常关心的问题。英国萨里食品研究协会这方面研究开发工作处于世界领先地位,他们开发出鉴定果汁、油脂和速溶咖啡等食品的掺假分析方法。 检验是否有较便宜的原料加到食品中的     

激发-发射矩阵荧光光谱用于鉴别百合掺假的研究

为了能够快速判别百合是否掺假,利用激发-发射矩阵（EEM）荧光技术对纯百合和掺假百合样品进行了荧光光谱分析,并构建了百合及其掺假百合的荧光指纹特征图谱;然后借助主成分分析-线性判别分析（PCA-LDA）和偏最小二乘-判别分析（PLS-DA）两种化学模式识别方法,对百合中掺假粉末的种类进行了快速鉴别和分类。实验结果表明：两个分类模型均能根据百合样本的EEM荧光光谱数据准确识别掺假百合样本,且正确分类率均高达95%。利用PCA-LDA和PLS-DA成功建立了快速判别百合掺假的新方法,同时完善了百合荧光指纹特征图谱,有望为建立更全面、更准确地评价百合药材的质量标准体系打下基础。     

浅析聚合酶链反应技术检测食品中沙门氏菌

聚合酶链反应技术在食品沙门氏菌检测中的实际应用中表现出灵敏度高、速度快、特异性强、简便、高效等特点,为食品检测技术的发展提供了有力的技术支持,因此在食品检测领域得以广泛的应用。本文就聚合酶链反应技术在食品沙门氏菌检测中的应用进行了探讨。     

奶粉掺假拉曼光谱成像检测新方法

本文采用拉曼光谱成像技术(Raman imaging)对掺杂奶粉进行快速检测,该技术有机结合了小尺度微区扫描和大尺度面积筛选功能,可高效采集奶粉样品信息.为了从复杂、变动的拉曼成像信号中准确识别掺假物质,本文发展了一种数据驱动的多尺度建模方法,以局部逼近的方式针对不同奶粉样品体系构建最佳小波基,自适应地提取拉曼成像信号中的掺假物质信息并加以甄别,最终以数据融合的方式建立多尺度模型.由此构建的光谱鉴定模型对奶粉掺假具有良好的识别能力,并有效避免了信息丢失.计算结果表明,该模型对未知样品的判别正确率为98.9%,可以半定量估计掺杂物浓度,为奶粉掺假识别提供了一种新方法.     

红外光谱技术在食品检测中的应用

过去十年中,红外光谱在全球食品工业中的应用已呈现出快速的增长趋势。傅立叶变换红外光谱(FTIR)技术得到许多研究者青睐。尤其是化学计量学方法在提取光谱信息和排除背景干扰方面取得良好效果后,人们重新认识红外光谱技术的价值,使红外光谱在食品检测中的应用得到快速发展。本文就红外光谱技术的原理和特征及相关专家学者对其在食品检测方面应用的研究成果进行综述,以期为食品企业的检验分析工作者在引进傅立叶红外光谱仪时提供参考。     

Influence of Carbon Material Supports on the Efficiency of the Isotope Exchange between Dalargine and Tritium

Radiochemistry - Isotope exchange between dalargine applied onto various supports [glass, activated carbon, few-layer graphite (FLG)] and molecular tritium, performed with activation on a tungsten...     

Simulation of the Performance of a Fundamental Neutron Physics Beamline at the High Flux Isotope Reactor

We study the expected performance of the proposed fundamental neutron physics beamline at the upgraded High Flux Isotope Reactor at Oak Ridge National Laboratory. A curved neutron guide transmits the neutrons from the new cold source into a guide hall. A novel feature of the proposed guide is the use of vertical focussing to increase the flux for experiments that require relatively small cross-section beams. We use the simulation code IB to model straight, multi-channel curved, and tapered guides of various m values. Guide performance for the current NPDGamma and proposed abBA experiments is evaluated.     

Isotope exchange reactions of trans-zeatin with tritium

Isotope exchange of trans-zeatin with high-activity tritium water and with gaseous tritium in solution, and also the solid-phase catalytic hydrogenation of this compound were studied. The isotope exchange of trans-zeatin with gaseous tritium, both in solution and without a solvent at 160°C and higher temperatures, is accompanied by virtually complete hydrogenation of the starting compound with the formation of tritium-labeled dihydrozeatin. The isotope exchange of trans-zeatin with high-activity tritium water allows preparation of tritium-labeled zeatin in 67% yield and molar activity of 0.68 PBq mol^?1. When the solid-phase isotope exchange is performed at 150–155°C, the reaction products contain tritium-labeled trans-zeatin along with the hydrogenation product, dihydrozeatin. At 170°C, the only reaction product is dihydrozeatin. Thus, the selectivity of tritium labeling varies with the temperature of solid-phase catalytic hydrogenation. Below 160°C, the solid-phase reaction can be performed selectively, i.e., with the preservation of the double bond in the starting trans-zeatin. Above 170°C, the selectivity is lost, and the compound is virtually fully hydrogenated to dihydrozeatin.     

Augmenting real data with synthetic data: an application in assessing Radio‐Isotope identification algorithms

The performance of Radio‐Isotope IDentification (RIID) algorithms using gamma spectroscopy is increasingly becoming important. For example, sensors at locations that screen for illicit nuclear material rely on isotope identification to resolve innocent nuisance alarms arising from naturally occurring radioactive material. Recent data collections for RIID testing consist of repeat measurements for each of several scenarios to test RIID algorithms. Efficient allocation of measurement resources requires an appropriate number of repeats for each scenario. To help allocate measurement resources in such data collections for RIID algorithm testing, we consider using only a few real repeats per scenario. In order to reduce uncertainty in the estimated RIID algorithm performance for each scenario, the potential merit of augmenting these real repeats with realistic synthetic repeats is also considered. Our results suggest that for the scenarios and algorithms considered, approximately 10 real repeats augmented with simulated repeats will result in an estimate having comparable uncertainty to the estimate based on using 60 real repeats. Published in 2009 by John Wiley & Sons, Ltd.     

Isotope selective near-resonant two-photon ionization of 41Ca isotope via the 4s11s 1S0 intermediate state

Isotope selective excitation of a 41Ca isotope using a near-resonant two-photon ionization scheme 4s2 1S0-->422.7924 nm,413.3685 nm4s11s 1S0-->514.5 nmCa+ has been proposed for using the 41Ca isotope in applications as a tracer in biomedical studies. The ionization efficiency and optical selectivity have been calculated for various powers of the excitation and ionization laser. Under the optimized excitation and ionization laser powers the ionization efficiency for the studied scheme is found to be 1.7x10(-4). The optical selectivity value is approximately 1.0x10(5) and both of these values are either comparable or slightly better than the earlier published work by our group. The overall ionization efficiency for the two-photon ionization scheme considering the throughput factor is 5x10(-3), which is 2 orders of magnitude higher than the stepwise excitation process. Therefore, the higher ionization efficiency of the process enables monitoring of the tracer isotope for longer durations. In combination with a mass spectrometer, an abundance sensitivity of approximately 10(10) can be obtained, which is adequate for biomedical applications.     

Conversion of O(2) into CO(2) for High-Precision Oxygen Isotope Measurements

An improved procedure of (18)O/(16)O ratio measurements by means of oxygen conversion to CO(2) is developed, which allows one to obtain the true δ(18)O values with a precision of ±0.05‰ in oxygen samples down to 7 μmol. The isotopic exchange between quartz glass and oxygen gas was measured in the temperature range of 600-900 °C, and it was found to be less than 0.2%.     

Migration of di‐(2‐ethylhexyl)adipate (DEHA) and acetyl tributyl citrate (ATBC) plasticizers from PVC film into the food stimulant of isooctane

Chemical migration from food packing is influenced by several factors such as nature of chemicals, complexity of food, temperature, packing material used and properties of the migrating substances. Chemical compounds that are incorporated within polymeric packaging materials may interact with food components during processing or storage and migrate into the food by jeopardizing the food safety. This migration is higher if food remains in contact with packing material for extended time. Polyvinyl chloride (PVC) film such as di‐(2‐ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC) are still widely used as a food packing material due to its flexibility, transparency and low water permeability. The present study covers the main migration phenomena of both plasticizers (di‐(2‐ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC)) from PVC‐film into isooctane food stimulant using a direct gas chromatographic method. An exposure period of 48 h at 30 °C and 4 °C was used. The obtained results showed DEHA levels ranging of 7.2 mg/dm² while, no ATBC migration from PVC‐film was observed. Results are discussed in relation to EU legislation proposed upper limit for DEHA specific migration (18 mg/L or 3 mg/dm²) and overall migration limit (OM) of 10 mg/dm².     

红外光谱法快速鉴别PE和PVC保鲜膜

利用傅立叶变换红外光谱仪直接采集PE和PVC食品保鲜膜的红外投射光谱,比较了两种食品保鲜膜的红外光谱特征,明确了各自主要特征峰的归属.通过检索标准谱库与标准谱图进行对照,对两种保鲜膜进行了定性鉴定.该方法不需要任何样品前处理过程,具有快速、方便、准确的优点,是对市场上两种食品保鲜膜进行快速定性鉴别的理想方法之一.     

Determination of Selected Perfluorinated Acids (PFCAs) and Perfluorinated Sulfonates (PFASs) in Food Contact Materials Using LC‐MS/MS

Perfluorinated compounds, including perfluorinated acids and perfluorinated sulfonates, are environmentally persistent. These compounds are commonly used in consumer products as stain/water/grease repellents in carpets and clothing, in cooking utensils as nonstick coating and in food contact materials as a coating. This paper explores the potential application of liquid chromatography coupled with tandem mass spectrometry (LC‐MS/MS) system for the measurement of selected perfluorinated acids and perfluorinated sulfonates in three different brands (A, B and C) of food contact materials, including wrapping papers, breakfast bags, baking papers and roasting bags. In this study, the highest contents of selected perfluorinated acids were identified for the breakfast bag samples (2.54–6.60 pg/cm²), especially for B and C brands with the concentration of 6.60 and 5.35 pg/cm², respectively, while the lowest content was noted in roasting bag samples (0.27–0.40 pg/cm²). The contents of perfluorinated sulfonates were inversed as compared with those of perfluorinated acids. The highest contents of selected perfluorinated sulfonates were found in roasting bag samples (1.38–5.17 pg/cm²), especially for B brand. The analysed perfluorinated sulfonates were not detected in any of the breakfast bag samples. The highest content of perfluorinated compounds were reported for B brand food contact materials. The data indicate a risk of food contamination by perfluorinated compounds from the commonly used food contact materials. Copyright © 2015 John Wiley & Sons, Ltd.     

Copper(II)-8-hydroxquinoline coprecipitation system for preconcentration and separation of cobalt(II) and manganese(II) in real samples

A separation-preconcentration procedure based on the coprecipitation of cobalt(II) and manganese(II) ions with copper(II)-8-hydroxquinoline system has been developed. The analytical parameters including pH, amount of copper(II) as carrier element, amount of 8-hydroxquinoline, sample volume, etc., was investigated for the quantitative recoveries of Co(II) and Mn(II). No interferic effects were observed from the concomitant ions which are present in real samples. The detection limits for analyte ions by three sigma criteria were 0.86microgL(-1) for cobalt and 0.98microgL(-1) for manganese. The validation of the presented preconcentration procedure was performed by the analysis of NIST SRM 2711 Montana soil and GBW 07605 Tea certified reference materials. The procedure presented was applied to the analyte contents of real samples including natural waters and some food samples with successfully analytical results.