湖南稻米镉和土壤镉锌的关系分析

在湖南省采集108 组稻米和土壤样品,测定稻米镉、土壤总镉、土壤有效态镉含量和有效态锌含量。电感耦合等离子体质谱法测定结果表明,稻米镉含量范围为0.015～1.05 mg/kg,平均值为0.272 mg/kg,其中超过70%的稻米样品镉含量在0.10～0.30 mg/kg范围内。土壤总镉、有效态镉、有效态锌含量范围分别为0.180～1.89、0.116～0.742、0.893～17.37 mg/kg,平均值分别为0.679、0.295、5.02 mg/kg。SPSS软件统计结果显示,稻米镉含量与土壤总镉和土壤有效态锌含量分别呈开口向上和开口向下的二次曲线关系（P=0.000）,而与土壤有效态镉含量呈正相关（P=0.000）。以上结果表明,稻米镉含量受到土壤有效态镉含量的促进,土壤中有效态锌含量高可抑制稻米对镉的积累。     

Desorption kinetics of Cd, Zn, and Ni measured in soils by DGT

DGT (diffusive gradients in thin films) was used to measure the distribution and rates of exchange of Zn, Cd, and Ni between solid phase and solution in five different soils. Soil texture ranged from sandy loam to clay, pH ranged from 4.9 to 7.1, and organic carbon content ranged from 0.8% to 5.8%. DGT devices continuously remove metal to a Chelex gel layer after passage through a well-defined diffusion layer. The magnitude of the induced remobilization flux from the solid phase is related to the pool size of labile metal and the exchange kinetics between dissolved and sorbed metal. DGT devices were deployed over a series of times (4 h to 3 weeks), and the DIFS model (DGT induced fluxes in soils) was used to derive distribution coefficients for labile metal (Kdl) and the rate at which the soil system can supply metal from solid phase to solution, expressed as a response time. Response times for Zn and Cd were short generally (<8 min). They were so short in some soils (<1 min) that no distinction could be made between supply of metal being controlled by diffusion or the rate of release. Generally longer response times for Ni (5-20 min) were consistent with its slow desorption. The major factor influencing Kdl for Zn and Cd was pH, but association with humic substances in the solid phase also appeared to be important. The systematic decline, with increasing pH, in both the pool size of Ni available to the DGT device and the rate constant for its release is consistent with a part of the soil Ni pool being unavailable within a time scale of 1-20 min. This kinetic limitation is likely to limit the availability of Ni to plants.     

In-situ speciation of Ni and Zn in freshwaters: comparison between DGT measurements and speciation models

The technique of DGT (diffusive gradients in thin films) was used for the first time to measure in situ the distribution of Zn and Ni between inorganic species and complexes with fulvic and humic acids in natural waters. With DGT, metals are bound to a resin embedded in a layer of hydrogel after diffusive transport through an adjacent layer of hydrogel. The metal concentrations in the waters can be quantified using simple diffusion equations. By using devices with hydrogels of different pore size, large and small complex species were discriminated. Inorganic species diffuse freely through all gels, but larger organic complexes with fulvic and humic acids diffuse less freely through more restricted gels (gels with smaller pore size). Systematic differences between DGT devices containing gels of different pore size were obtained. Their calibration for the diffusion of fulvic and humic complexes allowed calculation of the concentrations of labile inorganic (Zn, 34.6 +/- 2.5 nM; Ni, 23.5 +/- 0.9 nM) and labile organic (Zn, 43.1 +/- 2.9 nM; Ni, 11.2 +/- 0.7 nM) complexes. The concentration of Zn measured by anodic stripping voltammetry in samples returned to the laboratory lay between the DGT-measured inorganic concentration and the total dissolved concentration, consistent with partial measurement of organic complexes of Zn. The speciation model WHAM successfully predicted the species distribution of Ni, Zn, and Cu, provided that competitive binding by Fe(III) was considered. Using the speciation models WHAM and ECOSAT, free ion activities of Zn and Ni were calculated from (1) the total inorganic species measured by DGT and (2) the total dissolved species and dissolved organic carbon. The calculations confirmed the good model predictions of metal-humic binding but highlighted problems with default databases used for the speciation of inorganic components.     

Volatiles Evaluation and Dielectric Properties Measurements of Chinese Spirits for Quality Assessment

The volatiles of Chinese spirits were evaluated using a fast gas chromatography analyzer (zNose™). The first derivative profile, retention time, and peak area were used to discriminate samples at various grades. Principal component analysis and canonical discriminant analysis were adopted for data analyses, where 100% classification was achieved. A network analyzer was also included in this study in order to explore the possibility of estimating the concentration of alcohol using the spirit’s dielectric properties. The dielectric constant and loss factor of 0–100% ethanol–water mixtures in 10% interval and 42%, 50%, 53%, 62%, and 64% ethanol–water mixtures, as well as spirits samples were measured and compared.     

黄酒熟麦曲中细菌多样性的评价

以黄酒熟麦曲为研究对象,采用聚合酶链式反应-变性梯度凝胶电泳(polymerase chan reaction-denaturing gradient gel electrophoresis,PCR-DGGE)与MiSeq高通量测序技术相结合的方法对其细菌多样性进行解析。DGGE结果表明:Bacillus(芽孢杆菌)、Weissella(魏斯氏菌)、Pediococcus(片球菌)、Staphylococcus(葡萄球菌)和Lactobacillus(乳酸杆菌)普遍存在于麦曲样品中。MiSeq高通量测序结果表明:熟麦曲中的细菌门主要为Firmicutes、Proteobacteria和Actinobacteria,平均相对含量分别为87.95%、9.00%和1.16%。熟麦曲中的细菌属主要为Bacillus (芽孢杆菌属)、Weissella(魏斯氏属)、Staphylococcus(葡萄球菌)、Klebsiella(克雷伯菌属)、Pantoea(泛菌属)和Lactobacillus(乳杆菌属),其平均相对含量分别为70.70%、8.55%、2.67%、2.29%、1.32%和1.07%。由此可见,Bacillus(芽孢杆菌)为熟麦曲中的优势细菌。     

Average NaCl Concentration in Cheese for Different Volume Ratios of Brine and Solid during Salting

Fick's second law for unsteady-state, one-dimensional diffusion in solid media from a well stirred solution of limited volume was used to develop mathematical equations for modeling the mass transfer of NaCl in cheeses during salting. A computational method was employed to solve the equations and analyze the suitable conditions for salt penetration in finite cylindrical cheeses. Various volume ratios of solution and solid were considered to determine the variation of NaCl concentration in cheeses. Experimental results were predicted by the proposed mathematical model with less than 10% error.     

黄酒对大鼠体重影响的初步研究

通过动物实验,初步研究了黄酒对体重的影响.按不同剂量给雄性SD大鼠灌喂黄酒10周,大鼠的体重增长率依次为对照组>中剂量组>高剂量组>低剂量组,但经方差分析,各组间的P>0.05,说明黄酒对大鼠的体重无明显影响.     

清香型白酒乳酸乙酯偏高的原因及解决措施

清香型白酒基酒(特别是二米查酒)中乳酸乙酯偏高,在生产中较为常见,主要是曲药、工艺、蒸馏、卫生等环节中存在问题,造成乙酸乙酯与乳酸乙酯比例失调。探明原因,找出相应的解决措施。     

印度对华生丝反倾销案影响评估

以理论分析为框架,就2002年印度对华生丝反倾销案对我国丝绸行业的经济影响进行了评估.评估后认为,该案所引发的反倾销调查效应和关税限制效应较为明显,但贸易转移效应不显著.印度通过实施反倾销措施,一定程度上实现了保护本国蚕丝产业的目的,但贸易限制性措施对市场行为的干预作用本质上还是有限的.     

Differential uptake, partitioning and transfer of Cd and Zn in the soil-pea plant-aphid system

The biomagnification of trace metals during transfer from contaminated soil to higher trophic levels may potentially result in the exposure of predatory arthropods to toxic concentrations of these elements. This study examined the transfer of Cd and Zn in a soil-plant-arthropod system grown in series of field plots that had received two annual applications of municipal biosolids with elevated levels of Cd and Zn. Results showed that biosolids amendmentsignificantly increased the concentration of Cd in the soil and the shoots of pea plants and the concentration of Zn in the soil, pea roots, shoots, and pods. In addition, the ratio of Cd to Zn concentration showed that Zn was preferentially transferred compared to Cd through all parts of the system. As a consequence, Zn was biomagnified by the system whereas Cd was biominimized. Cd and Zn are considered to exhibit similar behaviors in biological systems. However, the Cd/Zn ratios demonstrated that in this system, Cd is much less labile in the root-shoot-pod and shoot-aphid pathways than Zn.     

稻谷中镉含量测定的测量不确定度评估

参考GB/T 5009.15—2003《食品中镉的测定》和《化学分析中测量不确定度的评估指南》,用原子吸收分光光度计石墨炉法测定了稻谷样品中的镉含量并对其进行测量不确定度的评估,分析测量结果不确定度的主要来源,计算合成不确定度和扩展不确定度。结果表明：稻谷样品中镉含量为0.14 mg/kg,其扩展不确定度为0.0047 mg/kg。     

Predicting Alcohol Yield from UK Soft Winter Wheat for Grain Distilling: Combined Influence of Hardness and Nitrogen Measurements

The work reported in this paper showed that whilst grain nitrogen is a key player in determining the alcohol yield obtained from soft winter wheat, other parameters such as grain hardness may also be important. A strong positive correlation was found between grain hardness and grain nitrogen and both parameters affected alcohol yield of processed wheat in a similar way. Although an inverse relationship between alcohol yield and grain nitrogen was observed at each of four growing sites, this relationship was stronger for wheat grown at moderate nitrogen sites than at higher or lower nitrogen sites. A similar inverse relationship, comparable to that obtained for nitrogen, was also found between alcohol yield and grain hardness. Further statistical analysis showed that an improved prediction of alcohol yield can be obtained based on measures of both hardness and total nitrogen, as opposed to total nitrogen alone. Residue viscosity did not appear to directly influence alcohol yield. However, some correlation was observed between both grain nitrogen and hardness and residue viscosity at certain sites. While correlation between nitrogen and residue viscosity was observed at the site with the highest nitrogen content, correlation between hardness and residue viscosity was observed at the two sites where nitrogen content was highest. Finally, scanning electron microscopy revealed that very high protein content was found to result in deformation of the starch structure, limiting access of starch during processing and lowering alcohol yield.     

Application of Response Surface Methodology to the Development of Rice Flour Yeast Breads: Objective Measurements

A gluten-free wheat bread replacement was developed from rice flour (80%) and potato starch (20%). Using objective measurements as responses, response surface methodology was utilized to find carboxymethylcellulose (CMC)-hydroxypropylmethylcellulose (HPMC)-water combinations which could successfully replace gluten in the rice flour yeast breads from each of three rice flours. CMC and water had the greatest effect on the responses measured; HPMC had the least. Rice bread formulations were found that resulted in breads which met wheat (white) bread reference standards for specific volume, crumb and crust color, Instron firmness and % moisture.     

Comparison of chemical modifiers for direct determination of Cd, Cu and Zn in food stuffs by solid-sampling-ETAAS

In this work, the capability of different chemical modifiers (Pd, Pd/Mg(NO₃)₂, Pd/NH₄NO₃, NH₄H₂PO₄, NH₄H₂PO₄/Mg(NO₃)₂) to eliminate the matrix effects in the direct determination of Cd, Cu and Zn in food-stuffs by solid sampling-electrothermal atomic absorption spectrometry was compared. The alternative analytical lines were used for determination of Cu (327.4 nm) and Zn (307.6 nm) in order to allow the introduction of reasonably high sample mass into the furnace. Mixed modifiers containing palladium were useful to eliminate the matrix effect in Cd determination. For Cu and Zn determination the application of Pd shows satisfactory analytical performance. In the determinations of Cd and Zn the phosphate containing modifiers shows elimination of matrix effects only when applying them to a partially pyrolysed sample (at 400 °C). The achievable limits of detection for Cd, Cu and Zn in solid samples were 0.279 ng g⁻¹; 0.020 μg g⁻¹ and 2.04 μg g⁻¹, respectively.     

A Feasibility Study on the Evaluation of Quality Properties of Chinese Rice Wine Using Raman Spectroscopy

Rapid analysis of Chinese rice wine (CRW) is an important activity for quality assurance and control investigations. In recent years, due to its insensitivity to water and fewer overlapped bands, Raman spectroscopy (RS) may provide more useful qualitative and quantitative information on functional groups of various chemical compounds in CRWs than the conventional spectroscopic technique (e.g., infrared spectroscopy); there has been a growing interest in the application of RS in the qualitative and quantitative analysis in food industry. In this study, the applicability of RS hyphenated with chemometrics using different pretreated spectra was examined to develop rapid, low-cost, and non-destructive method for quantification of four enological parameters involved in CRW quality control. Partial least square (PLS) was used for building the calibration models for the four chemical parameters based on the full RS spectrum. The model was also optimized by using efficient wavelength selection algorithm, i.e., synergy interval partial least square (SiPLS) algorithm. In addition, soft independent modeling of class analogy (SIMCA) and linear discriminant analysis (LDA) were used as classification techniques to predict the brands (wineries) of CRW samples. The results demonstrated that compared with the PLS model using all wavelengths of RS spectra, the prediction precision of model based on the spectral variables selected by SiPLS was significantly improved with high values of the coefficient of determination (>0.90), residual predictive deviation (>3.0), and range error ratio (>10) for all of the four quality parameters. The SIMCA and LDA results, characterized by high percentages of correct classification (96.67 and 100.00 % as average value in prediction for SIMCA and LDA, respectively), showed that samples belonging to a particular brand could be correctly classified. The overall results indicated the suitability of RS combined with efficient variable selection algorithm to rapidly control the quality of CRW.     

激光拉曼光谱仪在A-K糖冷却结晶中的应用研究

采用激光拉曼光谱法对水中A-K糖的浓度进行测定。通过比较纯水和加了A-K糖后溶液之间拉曼谱图的变化找到了A-K糖特征峰位置为1 657 cm~(-1),以1 657 cm~(-1)与水的拉曼光谱特征峰3 427 cm~(-1)的相对强度比值和溶液浓度建立线性关系,从而建立校准模型。经验证此法可简单快速测定溶液浓度,最终利用此标准曲线实现对A-K糖在水中的冷却结晶的实时监测,这对研究A-K糖工业化生产过程的在线监控有着重大意义。     

不同消化方法对大蒜中锰、锌、铜、镉含量的影响

目的：研究不同消化方法对大蒜中Mn，Zn，Cu争Cd微量元素含量的影响。方法：采用干法灰化争湿法消化预处理大蒜，干法灰化以时间争温度做单因素实验；湿法消化以酸的比例、放置时间争种类做单因素实验，通过正交实验确定最佳消化条件，利用原子吸收分光光度法测定大蒜中Mn，Zn，Cu争Cd的含量。结果表明：大蒜中Mn，Zn，Cu争Cd的最佳消化条件，干法灰化是Mn450℃，4h；Zn650℃，6h；Cu550℃，4h；Cd 450℃，4h。湿法消化是Mn：HNO3：H2SO4=5l1，16h；Zn：HNO3：HCl=7：1，12h;Cu：HNO3：H2O=1：1，12h；Cd：HNO3：H2SO4=1：2，12h。测定结果的相对标准偏差均在2．0％以下，回收率为99％～101％之间。     

Understanding the differences in Cd and Zn bioaccumulation and subcellular storage among different populations of marine clams

The marine clams Mactra veneriformis were collected from three different locations in a contaminated bay in Northern China. Another species of clams Ruditapes philippinarum was collected from the same contaminated bay as well as from a relatively clean site in Hong Kong. The indices of Cd and Zn bioaccumulation (assimilation efficiency, dissolved uptake rate, and efflux rate), tissue concentration, subcellular distribution, metallothionein (MT) content, and clearance rate of the clams were subsequently quantified in these populations in the laboratory. In the two species of clams, the population with a higher Cd tissue concentration assimilated Cd and Zn more efficiently, in correlation with an increase in the Cd associated with the metallothionein-like protein (MTLP) fraction. The subcellular partitioning of Zn was similar among the different populations. The dissolved uptake rates of Cd and Zn were not influenced by the different tissue concentrations of metals in the clams. However, the clam R. philippinarum from the contaminated site reduced their Zn uptake rate constants in response to increasing Zn concentration in the water. Differences in Cd and Zn tissue concentrations had little influence on the metal efflux rate constant and the clams' clearance rate. Our results indicate that the higher Cd and Zn tissue concentrations observed in these two species may be partially caused by the high levels of metal assimilation. Populations living in contaminated environments may be able to modify their physiological and biochemical responses to metal stress, which can subsequently alter trace metal bioaccumulation to aquatic animals. The relative significance of dietary uptake and the potential trophic transfer of metals in the contaminated areas may be substantially different from those in the clean environments.     

适用于黄酒生物酸化浸米的乳酸菌筛选

浸米是黄酒生产中的重要环节。使用高锰酸钾-溴化钾平板透明圈法,快速从黄酒酿造环节的样品中分离筛选出160株产乳酸细菌;通过生理特性试验、浸米水产酸情况、抑菌情况和产生物胺试验,得到1株乳酸菌适合用于生物酸化浸米,经16S rRNA寡核苷酸碱基序列分析鉴定菌株为植物乳杆菌。将其应用于生物酸化浸米过程中可以快速提高米浆水的酸度,缩短浸米时间,并抑制杂菌的生长,提高浸米过程的稳定性,且有效地降低浸米水中生物胺质量浓度。