对食品中铝含量国标测定方法的改进

对国标GB/T 5009.182-2003中样品处理方法做了改进,用干法灰化代替湿法消解,解决了国标方法中由于pH值和高氯酸对显色反应的影响造成检测结果不准确的问题.采用干法灰化-分光光度法测定了食品中的铝含量,测定结果的相对标准偏差为1.6%(n=6),回收率为94.3%～100.7%.该方法适用于大批量食品中铝的快速检测.     

Recent advances in the environmental applications of biosurfactants

Biosurfactants can be used for heavy metal or organic contaminant removal from contaminated soil or for bioremediation enhancement. Most research has been performed on the use of rhamnolipids. However, present and future studies involve new biosurfactants and new applications as sustainable, renewable additives for nanoparticle production and use.     

New era for mucosal mast cells: their roles in inflammation,allergic immune responses and adjuvant development

To achieve immune homeostasis in such a harsh environment as the intestinal mucosa, both active and quiescent immunity operate simultaneously. Disruption of gut immune homeostasis leads to the development of intestinal immune diseases such as colitis and food allergies. Among various intestinal innate immune cells, mast cells (MCs) play critical roles in protective immunity against pathogenic microorganisms, especially at mucosal sites. This suggests the potential for a novel MC-targeting type of vaccine adjuvant. Dysregulated activation of MCs also results in inflammatory responses in mucosal compartments. The regulation of this yin and yang function of MCs remains to be elucidated. In this review, we focus on the roles of mucosal MCs in the regulation of intestinal allergic reaction, inflammation and their potential as a new target for the development of mucosal adjuvants.     

高效液相色谱法测定强化食品中维生素C的含量

建立了强化食品(饮料、奶粉、含乳饮料、大米、果泥及果冻)中维生素C含量的高效液相色谱检测方法。优化了样品处理方法,在水浴控温和避光条件下处理样品,避免维生素C被氧化。选用Tech Mate C18–ST(250 mm×4.6 mm,5μm)反相色谱柱,以0.05 mol/L磷酸二氢钾缓冲溶液(p H 3)为流动相,流量为1.0m L/min,检测器为光电二极管阵列检测器,检测波长为266 nm。线性范围为0.2~100μg/m L,相关系数为0.999 6,果泥中维生素C的定量限为20 mg/kg,其它为100 mg/kg,加标回收率为82.2%~107%,测定结果的相对标准偏差为1.23%~6.86%(n=8)。该方法简单快速,其灵敏度、准确度和精密度均能满足强化食品中维生素C的检测要求。     

Territorial origin of olive oil: representing georeferenced maps of olive oils by NMR profiling

ABSTRACT Proton NMR profiling is nowadays a consolidated technique for the identification of geographical origin of food samples. The common approach consists in correlating NMR spectra of food samples to their territorial origin by multivariate classification statistical algorithms. In the present work, we illustrate an alternative perspective to exploit territorial information, contained in the NMR spectra, which is based on the implementation of a geographic information system (GIS). Nuclear magnetic resonance spectra are used to build a GIS map permitting the identification of territorial regions having strong similarities in the chemical content of the produced food (terroir units). These terroir units can, in turn, be used as input for labeling samples to be analyzed by traditional classification methods. In this work, we describe the methods and the algorithms that permit to produce GIS maps from NMR profiles and apply the described method to the analysis of the geographical distribution of olive oils in an Italian region. In particular, we analyzed by ¹H NMR up to 98 georeferenced olive oil samples produced in the Abruzzo Italian region. By using the first principal component of the NMR variables selected according to the Moran test, we produced a GIS map, in which we identified two regions incidentally corresponding to the provinces of Teramo and Pescara. We then labeled the samples according to the province of provenience and built an LDA model that provides a classification ability up to 99% . A comparison between the variables selected in the geostatistics and classification steps is finally performed. Copyright © 2016 John Wiley & Sons, Ltd.     

XPS analysis of bio‐organic systems

A survey of the literature is made for the XPS analysis of food products (mainly spray‐dried powders, which reveal a considerable surface enrichment in lipids) and of microorganisms and related systems (extracellular polymer substances and biofilms). This survey is used as a background for discussions and recommendations regarding methodology. Sample preparation methods reviewed are freeze drying, analysis of frozen hydrated specimens and adsorption of surface‐active biocompounds on model substrates. Peak decomposition is a way to increase the wealth of information provided by the XPS spectra. It should be performed after a check that sample charge stabilization is satisfactory. Moreover, ensuring the precision needed to make comparisons within sets of samples may involve a trade‐off between imposing constraints and generating information. The examination of correlations between spectral data in the light of chemical guidelines is useful to validate or improve peak decomposition and component assignment, and may also upgrade the chemical information regarding speciation. Further upgrading may be achieved by expressing marker XPS data in terms of concentrations of compounds of interest. Different methods of computation are discussed, providing a composition in terms of ingredients, classes of biochemical compounds, or various organic and inorganic compounds. As an alternative or complement to this deterministic approach, multivariate analysis of suitable spectral windows provides spectral components, which may be used for comparing samples, and which may have a direct chemical relevance or be used to identify features of interest. Copyright © 2011 John Wiley & Sons, Ltd.     

Teil II: Ergebnisse bei der Bestrahlung einzelner Nahrungsmittelgruppen (Zusammenfassender Bericht)

Nachdem im ersten Teil dieser Arbeit [170] einige Grundprobleme der Nahrungsmittelbestrahlung behandelt wurden, sollen nun die bei der Bestrahlung wichtiger Nahrungsmittelgruppen erzielten Ergebnisse dargelet und eine Einschätzung der Entwicklungstendenzen versucht werden.     

Determination of metoserpate,buquinolate, and diclofenac in pork,eggs, and milk using liquid chromatography–tandem mass spectrometry

In this work, a method was developed for the simultaneous determination of residual metoserpate, buquinolate and diclofenac in pork, milk, and eggs. Samples were extracted with 0.1% formic acid in acetonitrile, defatted with n‐hexane, and filtered prior to analysis using liquid chromatography–tandem mass spectrometry. The analytes were separated on a C₁₈ column using 0.1% acetic acid and methanol as the mobile phase. The matrix‐matched calibration curves showed good linearity over a concentration range of 5–50 ng/g with coefficients of determination (R²) ≥0.991. The intra‐ and inter‐day accuracies (expressed as recovery percentage values) calculated using three spiking levels (5, 10, and 20 μg/kg) were 80–108.65 and 74.06–107.15%, respectively, and the precisions (expressed as relative standard deviation) were 2.86–13.67 and 0.05–11.74%, respectively, for the tested drugs determined in various matrices. The limits of quantification (1 and 2 μg/kg) were below the uniform residual level (0.01 mg/kg) set for compounds that have no specific maximum residue limit (MRL). The developed method was tested using market samples and none of the target analytes was detected in any of the samples. The validated method proved to be practicable for detection of the tested analytes in pork, milk, and eggs.     

High sensitivity chemiluminescence enzyme immunoassay for detecting staphylococcal enterotoxin A in multi-matrices

In this study, detection of staphylococcal enterotoxin A (SEA) in multi-matrices using a highly sensitive and specific microplate chemiluminescence enzyme immunoassay (CLEIA) has been established. A pair of monoclonal antibodies (mAbs) was selected from 37 anti-SEA mAbs by pairwise analysis, and the experimental conditions of the CLEIA were optimized. This CLEIA exhibited high performance with a wide dynamic range from 6.4 pg mL⁻¹ to 1600 pg mL⁻¹, and the measured low limit of detection (LOD) was 3.2 pg mL⁻¹. No cross-reactivity was observed when this method was applied to test SEB, SEC1, and SED. It has also been successfully applied for analyzing SEA in a variety of environmental, biological, and clinical matrices, such as sewage, tap water, river water, roast beef, peanut butter, cured ham, 10% nonfat dry milk, milk, orange juice, human urine, and serum. Thus, the highly sensitive and SEA-specific CLEIA should make it attractive for quantifying SEA in public health and diagnosis in near future.