Binding of four heavy metals to hemicelluloses from rice bran

This paper demonstrates that rice bran hemicellulose A (RBHA), hemicellulose B (RBHB) and hemicellulose C (RBHC) have the potential for binding heavy metal ions. The quantity of metal ions bound varies from one rice bran fibre to another. As it can be inferred from the results of the study, RBHB was characterised by the highest capacity for metal ion (Pb, Cu and Cd) binding, followed by RBHC and RBHA. Binding of heavy metals to insoluble dietary fibre (RBDF) and cellulose from rice bran were found to be poor. Lignin from rice bran was the least active fraction for binding heavy metal ions.     

米糠稳定化方法的实验研究

分别利用干热、湿热、微波加热等处理方式,探讨了稳定米糠的有效方法。以过氧化物酶残余活力为标准进行比较,将3种稳定化米糠置于37℃储藏30d,比较其游离脂肪酸的变化。研究结果表明:相对于干热和湿热稳定方法,微波加热米糠是一种较为有效的处理方法。     

Dining at the periodic table: metals concentrations as they relate to recycling

A correlation between the prices of a variety of substances and their dilutions in their initial matrices was shown in 1959 by T.K. Sherwood. The research presented here shows that the relationship holds for engineering metals today, which we termed the metals-specific Sherwood plot. The concentrations of metals in products (e.g., printed wiring boards and automobiles) and waste streams (e.g., municipal solid waste, and construction and demolition debris) were plotted with this correlation. In addition, for the products and waste streams that undergo disassembly at end-of-life, the metals concentrations of the disassembled components were also plotted. It was found that most of the metals that are currently targeted for recycling have post-disassembly concentrations that lie above the metals-specific Sherwood plot (i.e., have concentrations that are more enriched than minimum profitable ore grades). This suggests that material concentration plays a role in the viability of recycling at end-of-life. As products grow in complexity and the variety of materials used, analyses such as this one provide insight for policymakers and those interested in material sustainability into macro-level trends of material use and future recycling practices.     

主要重金属在污染稻谷籽粒中的分布规律研究

以湖南省稻谷为研究对象,检测分析稻谷籽粒的稻壳、糠粉、糙米、精米等加工产品中无机As、Cd、Pb、Hg 4种重金属的变化分布规律,并研究了当前稻谷加工工艺对主要重金属的脱除效果。结果表明:无机As、Cd、Pd、Hg 4种重金属均表现出糠粉中的含量显著高于其他部位的含量。碾米加工工艺可同时消减稻谷中4种重金属的含量,其中无机As消减效果最好,消减幅度可达39%。无机As、Cd、Pb、Hg在精米与糙米中的含量均成正比,其比值分别为0.61、0.93、0.83、0.93。通过该比值关系,可通过碾米工艺获得重金属含量达标的稻谷无机As、Cd、Pb、Hg的限量值分别为0.328、0.215、0.241、0.021 5 mg/kg。     

Statistical approaches to estimating mean water quality concentrations with detection limits

We review statistical methodology for estimating mean concentrations of potentially toxic pollutants in water, for small samples that are not normally distributed and often contain substantial numbers of nondetects, i.e. samples that are only known to be below some set of fixed thresholds. Maximum likelihood estimation (MLE) and regression on order statistics (ROS) are two main approaches that dominate the literature, with transformation bias under non-normality that increases with the severity of censoring being the main problem. We consider exact maximum likelihood estimators in conjunction with the Box-Cox transformation and propose the Quenouille-Tukey Jackknife as a method for bias reduction and variance estimation. Exact maximum likelihood estimators resulting from the expectation-maximization (EM) algorithm are exhibited in a simple heuristic form that also provides estimated values for the nondetects as subsidiary outputs. We show in simulationsthatthetwo main approaches perform well for the log-normal and gamma distributions as long as the jackknife is employed to reduce bias. Bias corrections to MLE used in the literature are shown to correct in the wrong direction under severe censoring. The jackknife is also used for estimating the variance of the both the MLE and ROS estimators. Robustness is improved by searching a class of power transformations (Box-Cox) for the best approximating normal distribution. We conclude that both the exact MLE and ROS procedures can be useful under varying experimental conditions. Limited simulations indicate that the ROS procedure is unbiased and has a smaller variance than the MLE under the log-normal distribution and is robust. The MLE performed better in simulations involving the gamma as the underlying distribution. We also compare the estimators for the mean and variance that one obtains from typical sets of water quality data, analyzing for copper, alumnium, arsenic, chromium, nickel, and lead.     

Evaluation of worldwide approaches to the use of HACCP to control food safety

Hazard Analysis by Critical Control Point (HACCP) is a management tool, developed in the late 1960s, to ensure the safety of foods for space flights. It was subsequently recognised as an effective alternative to conventional end-point-testing by the World Health Organisation (WHO) and the United States Food and Agriculture Organisation (FAO), amongst others, and recommended for use in commercial food production. HACCP principles are now incorporated in national food safety legislation of many countries, as well as a likely future component of the standardisation of international food quality control and assurance practices. However, governments and food companies have interpreted HACCP differently. This paper describes the basic principles of HACCP, and evaluates its implementation in the European Union, North America, Australia and New Zealand, and in developing countries. The ‘Zurich House of Food-Safety’ approach was identified as the most rigorous (and possibly most effective) interpretation of HACCP, while the Australian food industry approach was identified as the most practical and readily applicable approach to HACCP.     

发光细菌法检测大米中的重金属

以明亮发光杆菌(P.phosphoreum)为受试物,对大米中的铅、镉、汞三种重金属进行了检测。结果表明,发光抑制率与重金属溶液的质量浓度呈正相关,相关系数大于0.96,各重金属离子对P.phosphoreum的毒性大小排序为Hg~(2+)Pb~(2+)Cd~(2+)。菌液与各重金属标准溶液加样体积比为1∶1,检测时间为30 min;Hg Cl2的线性范围为0.02~1.6 mg/L,Pb(NO_3)_2的线性范围为2~20 mg/L,Cd Cl_2的线性范围为2~64 mg/L;样品加标回收率范围为70.12%~93.5%,相对标准偏差范围为5.31%~13.25%。该检测方法简便,成本低,精确度较高,测量结果直观。     

Measuring and predicting environmental concentrations of pesticides in air after application to paddy water systems

In this study, the volatilization of five pesticides applied to an artificial flooded paddy field was assessed using the theoretical profile shape (TPS) and the integrate horizontal flux (IHF) techniques. The dataset derived was utilized to improve the volatilization routine of the rice water quality (RICEWQ) model. The masses of pesticides ethoprophos, procymidone, metalaxyl, chlorpyrifos, and chlorpyrifos methyl volatilized from paddy water and their concentrations in paddy water were determined for a period of 6 d after application. The highest and lowest volatilization losses were observed for chlorpyrifos and metalaxyl, respectively, accounting for 3.3% and 0.03% of their initially applied amount. A rapid pesticide dissipation was evident in paddy water during the study period. The RICEWQ model was used to simulate the fate of pesticides in the artificial paddy system. The Kvolat, an empiric coefficient used by the model as an input parameter, was calculated for all pesticides through model calibration. RICEWQ simulated well the fate of pesticides in paddy water. A significant regression correlation between Henry's law constant (Hk) and Kvolat of the studied compounds was established which could facilitate the parametrization of the model for describing pesticide volatilization.     

Heavy metals concentrations in dairy cow feedstuffs from the south of Iran

ABSTRACT

Levels of lead, cadmium, mercury, copper and zinc elements in feedstuffs were measured by inductively coupled plasma-optical emission spectrometry. A total of 216 feedstuffs samples including corn silage, alfalfa hay, wheat straw, full ration pellet, wheat bran and barley were collected from polluted and unpolluted regions during four seasons and prepared with wet digestion. Lead and mercury concentrations did not differ significantly in various feedstuffs, but cadmium level was significantly the highest in barley samples (p < 0.05). All feed material samples had lead, cadmium and mercury concentrations well below the maximum levels allowed by the European Union. The lowest and highest levels of both copper and zinc were found in wheat straw and wheat bran, respectively, but their maximum content did not exceed the legal limits. In contrast to the sampling area, season significantly (P < 0.05) affected heavy metal levels, except for zinc, in feedstuffs.     

Evaluation of trace and toxic element concentrations in Paris polyphylla from China with empirical and chemometric approaches

Trace and toxic elements in Paris polyphylla samples were determined by flame and graphite furnace atomic absorption spectrometry following microwave-assisted acid digestion, based on a mixture of nitric acid and hydrogen peroxide. The whole procedure, including sample preparation, digestion and measurements, was successfully validated against CRM GBW07603 (bush twigs and leaves). In order to get a better insight into the elemental patterns, common chemometric approaches to data evaluation, such as principal component analysis (PCA) and hierarchical cluster analysis (HCA), were used as classification techniques. Five significant groups classified by PCA were attributed partly to significant influential sources. HCA revealed five groups of P. polyphylla samples based on their trace and toxic element concentrations.     

稻谷重金属检测和去除方法的研究进展

现代工业快速发展导致部分稻谷污染了一定程度的重金属,解决稻谷重金属污染问题是保障粮食安全的重要内容。本文基于国内外的研究现状,首先总结比较了重金属检测方法的优缺点,其次总结了重金属在稻谷中的分布及存在形态,最后重点综述了对稻谷加工各个环节产物采取的重金属去除方法,展望了今后的研究方向,为重金属污染稻谷的合理利用提供借鉴。     

广州市市售大米中铬污染水平及健康风险评价

目的了解广州市市售大米中铬污染情况,评价重金属铬经大米途径摄入的健康风险。方法广州市市售大米经微波-离子交换柱分离,以石墨炉原子吸收法直接测定总铬、六价铬含量,采用国家标准GB 2762—2012《食品安全国家标准食品中污染物限量》规定的限量值评价大米中重金属铬的污染水平。采用2002年广东省居民膳食营养与健康状况调查数据,评价不同人群通过大米途径对铬的膳食暴露情况,并参照中国营养学会对总铬的最高上限标准以及美国环保局(EPA)的《致癌风险评价指南》为标准,对大米中的总铬和六价铬进行人群的健康风险评价。结果广州市市售大米样品中总铬、六价铬的检出率均为100%,总铬的超标率为26.67%(8/30),重金属铬污染对人群的健康危害低于中国营养学会标准,成人低于EPA标准,但是14岁以下儿童健康风险高于EPA标准。结论广州市市售大米受到铬污染,广州市居民成人经大米途径摄入重金属铬的健康风险较低,但是对14岁以下暴露儿童可能存在潜在危害,需采取有效措施防止大米铬污染。     

大米食味品质预测评价模型的建立及应用

选取与大米食味品质相关性高的主要化学成分含量、蒸煮特性、糊化特性、质构特性等指标进行测定,利用主成分分析对所得到的指标数据统计分析,构建食味品质预测评价模型,并用该模型对所选粳米、籼米进行评价.通过感官评价法的食味值对建立的模型进行检验,两种方法具有很好的一致性,表明该评价模型可以准确客观的评价大米食味品质.     

大米中重金属污染及其脱除技术研究进展

现代工业的快速发展,致使我国大米重金属污染问题日益严重。针对我国大米的生产和消费情况以及重金属的污染现状,综述了几种行之有效的重金属检测方法,并对目前大米中重金属污染的脱除技术进行了总结和分析,为今后治理大米中的重金属污染指明了研究方向。     

Evaluation of compositional and nutritional equivalence of genetically modified rice to conventional rice using in situ and in vitro techniques

BACKGROUND: Concerns that genetically modified (GM) rice may pose nutritional risks have led to the need for studies comparing its nutritional composition with that of its isogenic counterpart. The present study explored the compositional and nutritional equivalence of rice grains and straw derived from a glufosinate herbicide‐tolerant GM rice (Bar68), its non‐transgenic conventional counterpart (D68) and a transgenic hybrid generation (X125S/Bar68) of Bar68 with conventional rice X125S. RESULTS: The chemical and nutritional composition, in vitro fermentation and in situ nylon bag degradation parameters were employed. Statistical comparisons to test the equivalence between D68, Bar68 and X125S/Bar68 were made with a criterion of maximum differences (scaled by D68) not exceeding 20%. The chemical and amino acid components of Bar68 and X125S/Bar68 were equivalent to those of D68, with the exception of Ca, P, K, Zn, cysteine and phenylalanine contents of grains and P and Mn contents of straw. Bar68 and X125S/Bar68 were equivalent to D68 in terms of in vitro fermentation and in situ degradation parameters of grains and straw, with the exception of the rapidly degradable component of neutral detergent fibre and the potentially degradable component of acid detergent fibre of straw. The maximum differences in some chemical components and nutritional indices were noted between D68 and X125S/Bar68. CONCLUSION: The results of this study indicated that grains and straw of the glufosinate herbicide‐tolerant GM rice Bar68 and its transgenic hybrid generation X125S/Bar68 were essentially equivalent in chemical composition and nutritive value to those of its non‐transgenic counterpart D68. Copyright © 2009 Society of Chemical Industry     

Measuring and predicting the spreading of dairy products in the mouth: sensory,instrumental and modelling approaches

In order to understand the mechanisms whereby the molecules responsible for sensory stimuli are released in the mouth, the aim of this study was to characterise and predict the spreading of semi-solid dairy products between tongue and palate using four complementary approaches, namely sensory analysis, instrumental measurement and analytical and numerical modelling. The products studied were dairy gels, whose physical representation is a yield-stress fluid. In the instrumental approach, spreading in mouth was simulated by a test in which a constant volume of sample was squeezed between two plates. It was performed in two phases, the first phase with a prescribed speed and the second with a prescribed force. The influence of product rheology, interface conditions, forces involved and kinematics of displacement on spreading area were studied by combining the instrumental and modelling approaches. For the dairy gels studied in this work, the consistency K was the most influent parameter on the spreading area. Also worth noting were the good correlations between the results obtained by the sensory, instrumental and modelling approaches. The approach adopted in this study could be used to predict spreading in the mouth of food products or boluses with a rheological behaviour of the yield-stress fluid type.     

松江区消费环节大米重金属污染状况及安全评价

目的 了解松江区消费环节大米中铅、镉、无机砷和总汞等重金属污染状况及摄入风险, 掌握本地区大米质量安全情况。方法 采集松江区消费环节大米样品344个, 测定铅、镉、无机砷和总汞含量, 采用单因子污染指数和内梅罗综合污染指数对大米中重金属污染程度进行评价, 并用可耐受摄入量对膳食风险进行初步评估。结果 大米中无机砷、铅、镉、和总汞的含量均符合食品安全国家标准, 平均含量分别为0.054、0.032、0.018和0.0023 mg/kg; 在344件样品中, 97%以上的单因子污染指数小于0.6, 综合评价为安全、处于清洁水平的样品占99.4%, 没有轻度污染以上的样品存在; 通过大米摄入铅、镉、无机砷和总汞的量远远低于可耐受摄入量, 但无机砷、镉在高暴露点位的膳食风险贡献率大于10%。结论 松江区消费环节大米重金属的污染情况比较乐观, 对人体健康的风险处于较低水平, 重金属安全情况总体可控。     

Evaluation of a probe for predicting beef tenderness

A series of three experiments were conducted to evaluate the performance of the MIRINZ (Meat Industry Research Institute of New Zealand) tenderness probe. In the first experiment, assessments on raw samples from two different muscles (longissimus lumborum and semimembranosus) were obtained using the tension head. Results indicated D50 values (torque at 50° of rotation) were the most highly related to both sensory (taste, olfactory, and feeling factors measured by a trained sensory panel) and consumer (hedonic ratings provided by untrained consumers) properties and were the values of choice, since all probe values were essentially measuring the same characteristics. In the second experiment, assessments were made using both the tension and shear heads on raw and cooked striploin (longissimus lumborum) steaks. Results confirmed probe values were essentially measuring the same characteristics, but indicated raw tension head, area 2 values (area before 50° of rotation) were more highly related to both sensory and consumer properties than were D50 values. However, probe values from raw samples did not account for a sufficient amount of variation in either sensory or consumer properties to be useful predictors of these traits, and stepwise, linear regression did not improve the predictive value of raw probe values, since all probe values were interrelated. Probe values on cooked samples indicated the shear head and area 3 values (area under the entire trace) were the most related to both sensory and consumer properties and were the values of choice. Based upon the amount of variation accounted for in sensory and consumer traits, probe area 3 values using the shear head on cooked samples provided greater predictive value for both sensory and consumer traits than Warner–Bratzler shear values obtained from steaks cooked either fresh or after being frozen and thawed. In experiment 3, correlations with individual, parametric character notes from the texture profiles of two different muscles provided no clear indication as to the textural properties being assessed by the probe. However, the MIRINZ probe appears to be a quick viable alternative to the Warner–Bratzler shear for providing an objective measure of cooked meat tenderness.     

Evaluation of some metals in Brazilian coffees cultivated during the process of conversion from conventional to organic agriculture

The aim of this study was to evaluate the presence of nutrients and toxic elements in coffees cultivated during the process of conversion, on organic agriculture, in southwest Bahia, Brazil. Levels of the nutrients and toxic elements were determined in samples of soils and coffee tissues from two transitional organic farms by atomic absorption spectrometry (FAAS). The metals in soil samples were extracted by Mehlich1 and USEPA-3050 procedures. Coffee samples from both farms presented relatively high levels of Cd, Zn and Cu (0.75, 45.4 and 14.9 μg g⁻¹, respectively), but were still below the limits specified by the Brazilian Food Legislation. The application of statistical methods showed that this finding can be attributed to the addition of high amounts of organic matter during the flowering tree period which can act on the bioavailability of metal ions in soils.