生物胺的检测方法评价

生物胺是一类含氮低分子化合物，对动植物和微生物有重要的生理作用。适量的生物胺有助于人体正常的生理功能，过量则会引起不良的生理反应。目前国内外食品中的生物胺的检测主要采用液相色谱，一般仅是组胺检测。实际上许多食品中还含有其它的生物胺（腐胺、尸胺、精胺、亚精胺、色胺、尸胺、苯乙胺、章鱼胺），且其存在会对组胺的毒性有协同作用。因此，多组分生物胺的同时检测对于食品的安全和水产品出口有着重要的意义。本文对国内外比较常见的生物胺检测方法作了叙述和比较。     

食物粒度和硬度对人牙釉质三体磨粒磨损特性的影响

在往复滑动摩擦磨损试验台上对比考察了三体磨粒磨损过程中,食物颗粒的粒度和硬度对人牙釉质摩擦学特性的影响。结果表明:当食物颗粒硬度较高时,随着粒度减小,稳态摩擦因数略有降低,牙釉质磨损表面形貌逐渐由剥落为主转变为犁削效应;对于低硬度食物颗粒,随着粒度增加,稳态摩擦因数显著降低,牙釉质磨损表面形貌则由犁削效应转变为轻微擦伤。当食物颗粒粒度相同时,食物硬度对牙釉质的摩擦与磨损行为均有明显影响,食物颗粒硬度越高,稳态摩擦因数越高,磨损越严重。     

Using atomic force microscopy to probe food biopolymer functionality

Atomic force microscopes (AFMs) generate images by “feeling” rather than “looking” at samples. This permits a magnification range spanning that associated with both the light and electron microscopes, but under the “natural” imaging conditions normally associated with light microscopes. Molecules and molecular interactions can be imaged at molecular or submolecular resolution in gaseous or liquid environments. By careful design of experiments it is possible to use AFM to probe how food biopolymers determine the structure and texture of food products. This approach will be illustrated through studies on food polysaccharides and proteins.     

特定化合物同位素分析技术在海洋食物网研究中的应用

海洋食物网研究是海洋生态系统研究中的重要部分。特定化合物同位素分析(CSIA)技术是一项研究海洋食物网的新技术，较测定总有机物的稳定同位素技术，为海洋食物网研究提供了更为深入和丰富的信息。通过脂肪酸、氨基酸等分子的稳定同位素特征，可以更细致更准确地了解食物网的营养结构、物质和能量的传递过程。该技术在海洋食物网研究中，特别是在海洋热液系统食物网研究之中表现出广泛的适用性。虽然特定化合物同位素分析技术仍有一些局限性有待改进，但在海洋食物网研究的应用中已经显示出很大的发展潜力。     

SEM studies of the morphology and chemistry of polar ice

Determining the microphysical location of impurities in natural ice from the polar regions is necessary for understanding the physical properties of ice and for assuring the integrity of ice core records. SEM, using a cold stage and X-ray microanalytical techniques, has proved to be the most powerful method so far for undertaking such work. Methods are adapted from those used to study frozen hydrated biological material. Sublimation within the cryo-chamber is often needed in order to concentrate impurities onto a plane, but this can lead to artifacts that must be recognized. Over 100 samples from different depths and sites in Greenland and Antarctica have been examined. Typical physical features, including air bubbles, clathrate hydrates of air, and dust particles are identified. The dust is found preferentially at grain boundaries in some samples; by pinning the boundaries, it can slow grain growth. Of the soluble material, chloride seems to be found most frequently in the ice lattice. Other impurities are found at grain boundaries, and only when the bulk concentration exceeds a threshold, at triple junctions. These findings give new insights into processes determining the physical properties of ice samples and of ice sheets, and new impetus for theoretical studies of the energetics that lead to this distribution.     

Abrasive wear characteristics of a zinc-based alloy and zinc-alloy/SiC composite

An attempt has been made in this investigation to assess the contribution of various parameters towards governing the abrasive wear response of a zinc-based alloy under the conditions of varying applied loads and sliding distances. The factors whose contribution has been examined include deterioration in the cutting efficiency of the abrasive medium, role played by the SiC particles (dispersed in the alloy matrix) in terms of their degradation and resistance offered by them against the destructive action of the abrasive, subsurface hardening of the matrix and such other related aspects. Four types of abrasion tests were conducted on the samples to achieve the goal. The (abrasion) tests involved the use of (i) fresh as well as preworn surfaces of the samples and (ii) fresh and degraded abrasive media in four different combinations.The study suggests that the mentioned factors contribute to a varying degree towards controlling the (high-stress) abrasive wear behaviour of the specimens. However, degradation in the cutting efficiency of the abrasive medium (through capping, clogging, attrition and shelling) dominates over the influence of other parameters such as abrasion induced subsurface hardening of the matrix. Reinforcement of the SiC particles in the alloy matrix offered improved wear resistance (inverse of wear rate) under less severe conditions such as at low applied loads, wherein the dispersoid (SiC) particles could be retained by the matrix due to low cutting depths made by the abrasive particles. The dispersoid particles deteriorated the wear response of the matrix under more severe conditions of abrasion, such as at high loads, because of larger cutting depths causing fracturing and partial removal of the reinforcement (SiC) particles. The observed wear response of the samples has further been substantiated through the characteristics of wear surfaces, debris particles and abrasive medium after testing the matrix alloy and composite in a typical test condition expected to affect the abrasive medium and test specimens to the largest extent.     

Microstructural origins of corrosion in a 20% SiCp/2124 aluminium alloy metal matrix composite

The microstructure of a metal matrix composite (MMC) consisting of 20 wt% 3 μm SiC particles in a 2124 Al alloy matrix has been examined and the relationship to corrosion pitting processes investigated. Standard bulk corrosion tests show that the MMC forms a higher density of pits than the unreinforced alloy, although the overall performance is similar as the pits are shallower. In a new addition to conventional characterization techniques, transmission electron microscopy samples have been directly subjected to ‘flash’ corrosion treatment and subsequently examined. This technique is shown to be effective in studying the initiation of pits. The SiC particles and the widespread 9 intermetallic precipitates are shown to play little, if any, role. A sparse population of features introduced during powder processing and consolidation procedures, probably linked with strong magnesium segregation, is suggested to be responsible for pit initiation.     

电感耦合等离子体质谱法(ICP-MS)测定运动员食品中铅、砷、镉、铜

Inductively coupled plasma mass spectrometry (ICP-MS) was applied to determine copper, arsenic, cadmium, lead in athletic food using Sc, Ge, In, Bi as an internal standard. The linear correlation factor for four elements are higher than 0.999. Recoveries of spiked samples are in the range of 85.5%-115.5% and precision was fine, RSD is lower than 5.0%. And these are close agreement with the reference values in three standard reference materials of GBW08503, NBS1568, GBW08571. It indicates that the method is simple, rapid, sensitive and accurate, which can meet the demand for copper, arsenic, cadmium, lead analysis in athletic food.     

Automated image analysis of atomic force microscopy images of rotavirus particles

A variety of biological samples can be imaged by the atomic force microscope (AFM) under environments that range from vacuum to ambient to liquid. Generally imaging is pursued to evaluate structural features of the sample or perhaps identify some structural changes in the sample that are induced by the investigator. In many cases, AFM images of sample features and induced structural changes are interpreted in general qualitative terms such as markedly smaller or larger, rougher, highly irregular, or smooth. Various manual tools can be used to analyze images and extract more quantitative data, but this is usually a cumbersome process. To facilitate quantitative AFM imaging, automated image analysis routines are being developed. Viral particles imaged in water were used as a test case to develop an algorithm that automatically extracts average dimensional information from a large set of individual particles. The extracted information allows statistical analyses of the dimensional characteristics of the particles and facilitates interpretation related to the binding of the particles to the surface. This algorithm is being extended for analysis of other biological samples and physical objects that are imaged by AFM.     

新工科背景下食品类专业人才创新实践能力培养模式的构建与实践

食品类专业人才的创新实践能力培养是食品产业的行业需求,该行业仍存在产业规模巨大而创造能力不足的矛盾问题。文章立足于新工科时代背景,结合高校食品学院在教学中存在的问题,从课程体系、资源整合、师资配置3个方面探究食品类专业人才创新实践能力培养模式的构建与实践,以期为增强食品类人才的创新能力和实践能力提供改革思路。     

室内环境对冷藏陈列柜内食品包温度影响的数值模拟

为研究冷藏陈列柜内食品包温度和室内环境因素之间的关系,本文应用数值模拟方法研究不同的风幕出口速度、室内温度和相对湿度对冷藏陈列柜内食品包温度分布的影响,并考虑辐射传热和传质对食品包温度分布的影响。数值计算结果表明:光照使前排食品包温度提高0.1～1.2℃;在所研究范围内,随着风幕出口平均速度升高,食品包温度降低,而随着室内温度和相对湿度的升高,食品包温度升高。风幕出口冷风平均速度每升高0.15m/s,柜内食品包温度降低0.2～1.1℃;当室内温度每升高2℃,食品包温度升高约0.3℃;室内相对湿度每升高20%,食品包温度升高约0.9℃。本研究可为食品质量的研究和冷藏陈列柜的优化设计提供参考。     

食品安全快速分析仪的研制及其应用-食品中亚硝酸盐的现场快速测定

研制出了一种用于农产品和食品中甲醛、吊白块、亚硝酸盐、硝酸盐、二氧化硫现场快速检测的车载式仪器,开发出配套的化学试剂盒和食品现场快速前处理设备。该仪器每个检测项目的分析时间控制在30分钟以内。该仪器主要用于质检和市场管理部门的现场流动检测。     

高效液相色谱荧光检测法测定植物性食品中阿维菌素类药物

建立了植物性食品中阿维菌素类药物(阿维菌素、伊维菌素、多拉菌素、甲氨基阿维菌素苯甲酸盐和乙酰胺基阿维菌素)残留量的高效液相色谱测定方法。用乙腈提取溶剂样品中的目标物,碱性氧化铝固相萃取小柱和炭黑氨基柱净化,经N-甲基咪唑和三氟乙酸酐衍生化后,用高效液相色谱-荧光检测器在激发波长为365nm,发射波长为475nm处测定。在添加浓度4.0～100μg/kg范围内,平均添加回收率在78.5%～99.2%之间,相对标准偏差在0.56%～7.25%之间,检出限为1.0μg/kg。方法简便、快速、准确。在0.004mg/L～2.0mg/L范围内,阿维菌素类药物标准工作溶液的色谱峰面积与质量浓度成良好的线形关系,相关系数为0.9995。     

MRT Letter: High resolution SEM imaging of nano‐architecture of cured urea‐formaldehyde resin using plasma coating of osmium

Nanoarchitecture of cured urea‐formaldehyde (UF) resins was examined with a field‐emission scanning electron microscope (FE‐SEM) after coating samples with osmium, which is considered to produce particles of considerably smaller size compared to other metal coatings used in SEM studies. This method enabled comparison of the nanoarchitecture of UF resins of low (1.0) and high (1.6) formaldehyde/urea (F/U) mole ratios to be made, based on imaging of extremely small size particles as part of UF resin architecture, not described before. Imaging revealed presence of relatively large globular particles (148.084–703.983 nm size range) as well as smaller substructures (28.004–39.604 nm size range) as part of the architecture of 1.0‐mole UF resin. Globular particles were also present in 1.6 mole UF resin, but of considerably smaller size (14.760–50.269 nm). The work presented demonstrates usefulness of osmium coating in unraveling the intricacies of the nanostructural organization of cured UF resins, prompting wider application of this immensely useful but grossly underutilized metal coating type in high resolution SEM examination of biological and materials samples. Microsc. Res. Tech. 76:1108–1111, 2013. © 2013 Wiley Periodicals, Inc.     

自动固相微萃取-气相色谱-质谱法测定食品接触材料中多环芳烃(PAHs)的迁移量

多环芳烃具有致癌性、致畸性及致突变性,为了快速、高效、绿色的检测食品接触材料中多环芳烃(PAHs)的迁移量,建立了自动固相微萃取-气相色谱-质谱联用（GC/MS）测定水和3%乙酸食品模拟液中16种多环芳烃迁移量的分析方法。对固相微萃取时间、萃取温度、解吸时间、振荡速率和离子强度等萃取条件进行了优化,并进行了方法的线性范围、检出限、回收率、精密度等实验。结果表明：方法的线性范围在0.01~5.0 μg/L之间;相关系数在0.997 9～0.999 7之间;模拟物中16种多环芳烃的回收率为73.47%～117.6%;相对标准偏差（n=5）在2.72%～14.70%之间。本方法适应于食品接触材料中16种多环芳烃的迁移量检测。     

分散型固相萃取-气相色谱串联质谱法测定食品中8种芳氧苯氧丙酸酯类除草剂的残留量

建立了大豆、绿茶、大米、胡萝卜、菠菜、豌豆、大蒜、草莓、蜂蜜、猪肉、鱼肉、鸡蛋等12种食品中8种芳氧苯氧丙酸酯类除草剂残留量的分散型固相萃取-气相色谱串联质谱(DSPE-GC-MS/MS)分析方法。样品由含1%冰醋酸的正己烷的饱和乙腈溶液提取,分散型固相萃取法净化,采用气相色谱-串联质谱分时段反应离子监测技术进行测定,外标法定量。所有农药在10~1 000μg.L-1范围内线性良好;方法定量限(LOQ)均低于10μg.kg-1;在10、20、40μg.kg-1三个添加水平下,大豆等12种代表性基质中所有农药的平均回收率均处于70%~120%之间,RSD≤13%;该方法选择性较好,不仅能够用于多种食品基质的残留检测,而且还能较好地解决本底成分相当复杂的大蒜基质极易出现的干扰问题。     

基于动态光散射信号分形的颗粒测量技术研究

颗粒的动态光散射信号具有分形特征，通过对其特征值的分析，可以得到颗粒粒径信息。采用100nm、200nm、500nm和1000nm4种亚微米粒径范围的标准聚苯乙烯乳胶颗粒样品，分别求取了它们的动态光散射信号的分形维数。实验结果表明，颗粒粒径越小，对应的动态散射光分形维数越大；粒径越大，分形维数越小。从而证明了用分形维数表征颗粒粒径的可行性。与相关方法相比，分形方法具有所需的采样数据少、计算简便、适于实时测量等特点。     

2000年我国食品机械市场需求预测

从宏观上分析了２０００年我国食品机械的市场需求，首先分析了９０年代新的经济环境对市场需求的影响，然后从食品工业的发展预测２０００年食品机械的市场需求，进而从食品工业的结构调整来分析食品机械的需求。     

A block‐on‐ring tribocorrosion setup for combined electrochemical and friction testing

The combined action of corrosion and wear can cause degradation of equipment, and thereby financial losses related to the renewal or repair of damaged equipment. In the food industry, metal degradation is a major concern since metal release eventually can cause health risks for consumers. This study describes a block‐on‐ring testing facility used to determine sliding wear, and additionally allowing for electrochemical measurements, such as potentiodynamic polarization curves and potentiostatic monitoring of current and potential. To verify the reliability and reproducibility of this block‐on‐ring tribocorrosion setup, the tribological and electrochemical behaviour of stainless steel sliding against a ceramic ring in sulphuric acid has been determined. Furthermore, a case taken from the food industry has been examined. The study shows that results made on the described block‐on‐ring testing facility are reliable and can provide improved information about material properties when the material is exposed to combined chemical and mechanical degradation. Copyright © 2007 John Wiley & Sons, Ltd.     

Errors in electromagnetic flow meter with magnetic particles

Magnetic admixtures change the magnitude and distribution of the magnetic field and virtual current in active fluid volume of electromagnetic flow meter, and measurement error appears. The value of error depends on the concentration, permeability and electric conductivity of magnetic admixtures and on the form of particles.The principles of error formation are investigated assuming that in the fluid with uniform properties there may be a small concentration of spherical particles, whose magnetic and electric properties are different from that of the fluid. An ideal electromagnetic flow meter with a rectangular duct and infinitely conductive large electrodes is assumed. The flat velocity profile is supposed. Measurement error is evaluated using the analogy between electrostatic, magnetic and electric current fields. The main causes of measurement error are examined. There is a deviation of densities of virtual current and magnetic flux inside particles, a deviation of mean values of magnetic flux and virtual current densities outside particles and a distortion of magnetic and virtual current fields in surroundings of particles.The magnetic particles with electric conductivity considerably greater than fluid conductivity are especially dangerous. A relative error in this case may exceed volume concentration of particles six times.For non-magnetic particles measurement error is absent independent of their conductivity.