Effect of deoxynivalenol detoxification by ozone treatment in wheat grains

Considering the wide existence of mycotoxin deoxynivalenol (DON) in wheat and derived products, finding ways to detoxify DON in wheat grains as original resources for food-chain contamination is very important to protect human health and reduce economic losses. This study aimed to evaluate the effectiveness of destroying DON in wheat via ozonation under different conditions, such as moisture content (MC), ozone concentration, exposure time, and form of raw-material. The achieved data showed that DON reduction significantly improved with increased ozone concentration and exposure time. The whole wheat flour (WWF) was easier to degrade than the wheat kernels. Higher MC decreased larger amounts of DON. The maximum reduction of DON was 20.10% for the MC group, compared with the 11.79% and 16.29% for the other MC groups. DON concentration decreased from 3.89 mg/kg to 0.83 mg/kg under the generally recognized Maximum Residue Limit (MRL) level of 1 mg/kg, when WWF was treated with 100 mg/L of ozone treatment for 60 min. The first-order kinetic model established in this work showed a good R-squared value (R² > 0.877) and was consistent with the results. Therefore, ozonation is an effective and rapid way to degrade DON in wheat, especially in whole wheat flour.     

Retention of deoxynivalenol and its derivatives during storage of wheat grain and flour

Fate of deoxynivalenol (DON) and its derivatives—deoxynivalenol-3-glucoside (D3G), 15-acetyldeoxynivalenol (15-AcDON) and 3-acetyldeoxynivalenol (3-AcDON) during six-month storage of wheat grain and flour was investigated. Wheat grain and flour polluted by DON, D3G, 15-AcDON and 3-AcDON were packaged in polyethylene bags, kraft paper bags and cloth bags, and stored at room temperature and 4–6 °C, and mycotoxin levels were analyzed by UPLC-MS/MS after storing for 30, 90 and 180 days. Levels of DON, 15-AcDON and 3-AcDON in wheat grain showed a generally decrease during the storage duration, and DON concentrations averagely decreased by 40–50%. An obviously increase of DON (more than 70%) and decrease of 15-AcDON and 3-AcDON were observed after storage in wheat flour. There were no significant differences of D3G levels in most of wheat grain and wheat flour samples after storage, but some increased dramatically with retention level up to 240%. The results suggested conversion of DON and its derivatives may occur during wheat grain and flour storage.     

Evaluation of dietary exposure to deoxynivalenol (DON) and its derivatives from cereals in China

Probabilistic estimation of dietary exposure to DON, including its acetylated derivatives, and type B trichothecenes from cereals and cereal-based products in Chinese populations was investigated in the current work. Different cut-offs as proposed Maximum levels (MLs) for DON in various raw cereals and/or cereal-based foods were assessed based on the risk assessment results. Occurrence data was documented from 31 provinces of China over the year 2010–2013. Food consumption data was obtained from the National Diet and Nutrition Survey conducted in 2002. Dietary exposure was implemented by Monte Carlo (MC) simulations and Bootstrap resampling. The exposure distributions were specified as percentiles with confidence intervals (95% CIs) and compared with the group provisional maximum tolerable daily intake (PMTDI) of 1 μg/kg bw/day and the group acute reference dose (ARfD) of 8 μg/kg bw/day for DON and its acetylated derivatives. Results indicate that 75% of children and 90% of the general population and the adults are under the group PMTDI value, while 99% of the three populations are under ARfD value. However, under the assumptions of the proposed cut-offs, the P99.9 percentiles would decrease significantly. The probabilistic assessment in this study indicated that high-end exposure to DON and its derivatives should be concerned, especially for children. Rigorous formulation of maximum limits for DON and its derivatives in the relevant foodstuffs combined with increased monitoring should be considered as an effective way to reduce risk.     

臭氧灭菌技术在现代制药工业中的应用

臭氧灭菌具有高效、广谱、无残留的优点,现被广泛使用于药品生产过程的消毒灭菌。     

Co-exposures of aflatoxins with deoxynivalenol and fumonisins from maize based complementary foods in Rombo,Northern Tanzania

Children consuming maize based foods in Tanzania may be exposed to multiple mycotoxins. We estimated co-exposures of aflatoxins with Deoxynivalenol (DON) and fumonisins for children in rural Tanzania. Food consumption by the children was estimated by twice administering a 24 h dietary recall questionnaire to mothers of 18–24 months old children in Kikelelwa village. Each mother also, provided a sample of maize based flour used for feeding her child in the previous day. Each child's body weight (bw) was measured by following standard procedures. Aflatoxins, DON and fumonisins were determined in each sample using validated HPLC methods. Exposures for a mycotoxin were estimated by multiplying flour consumption (g/child/kgbw/day) by its contamination (μg/kg). Complete data were obtained for 41 children. Maize flour consumption ranged from 16 to 254 g/child/day. Thirteen (32%) of the 41 children consumed flour with detectable aflatoxin levels (range, 0.11–386 μg/kg), resulting in exposures from 1 to 786 ng/kg bw/day. All these children exceeded the aflatoxins exposure of concern (0.017 ng/kg bw/day). Eighteen (44%) of the children consumed flour with detectable DON levels (57–825 μg/kg) and 34 (83%), detectable fumonisins levels (63–2284 μg/kg), resulting in respective exposure ranges of 0.38–8.87 μg/kg bw/day and 0.19–26.37 μg/kg bw/day. Twelve (66%) of the DON exposed children and 56% of the fumonisins exposed children exceeded the respective provisional tolerable daily intakes of 1 μg/kg bw and 2 μg/kg bw. Co-exposures for aflatoxins with both DON and fumonsins were determined in 10% of the 41 children. Co-exposures of aflatoxins with fumonisins alone were found in 29% and of fumonisins with DON alone in 41% of the children. The study showed that children consuming maize based complementary foods in Northern Tanzania are at a risk of exposure to multiple mycotoxins. We recommend adoption of appropriate measures to minimize exposures of multiple mycotoxins in Tanzania.     

Effect of milling on the content of deoxynivalenol,nivalenol, and zearalenone in Japanese wheat

The effect of milling on the content of zearalenone (ZEA), a Fusarium mycotoxin, in a semi-processed wheat product was investigated and compared with that of deoxynivalenol (DON) or nivalenol (NIV). Two grain samples of Japanese soft wheat varieties, norin 61 and chikugoizumi, were milled to obtain three breaking flours (1B, 2B, 3B), three middling flours (1M, 2M, 3M) and two outer-layer fractions (bran and shorts). Patent flour for human consumption was made from 1B, 1M, 2B and 2M flours, while low-grade flour for animal feed was made from 3B to 3M flours. The contents of ZEA in patent flour, low-grade flour, bran and shorts were analyzed by an in-house validated analytical method using solvent extraction, multifunctional cartridge cleanup, and HPLC-fluorescence detection. A greater than 50% reduction in ZEA was observed in the patent flour of both samples, while 4–74% reduction in DON and NIV in the patent flour of the same two samples was observed. The results of this study revealed that the transfer ratios of ZEA had different features from those of deoxynivalenol and nivalenol.     

Screening of deoxynivalenol contamination in durum wheat by MOS-based electronic nose and identification of the relevant pattern of volatile compounds

Fungal volatile metabolites can be used as an indicator of mycotoxins occurrence in cereals. A rapid, easy-to-perform and non-invasive method using an electronic nose based on metal oxide sensors was developed to distinguish the quality of durum wheat samples in three classes based on the content of the mycotoxin deoxynivalenol (DON): class A ([DON] < 1000 μg/kg), class B (1000 ≤ [DON] ≤ 2500 μg/kg;) and class C ([DON] > 2500 μg/kg). Two different approaches were tested by performing 525 analyses of naturally contaminated durum wheat either on whole and ground kernels. Discriminant Function Analysis (DFA) provided calibration models that permitted to classify wheat samples with mean recognition percentages (R) for whole and ground kernels of 69.3% and 86.7%, respectively. Samples belonging to class A were better recognized than those belonging to classes B and C. The e-nose method applied to the analysis of ground wheat showed highest mean recognition percentage (R = 82.1%) in validation. By considering data with recognition percentage rate (R_r) higher than 80% in validation, performances of this method were further improved in terms of either mean recognition percentage (R = 90.1%) and percentage of misclassified samples (4%). An SPME-GC–MS method was also developed that allowed to characterize the pattern of volatile compounds of durum wheat samples. A positive (trichodiene, longifolene, 3-methyl butanal, tridecane, γ-caprolactone, 6,10,14-trimethyl-2-pentadecanone) or negative (hexadecane, 2,3,7-trimethyl-decane, 4,6-dimethyl-dodecane) association with DON content was observed. These results confirm that the developed e-nose method could be used as useful tool for high throughput screening of DON contamination in durum wheat.     

Distribution of deoxynivalenol and zearalenone in milled germ during wheat milling and analysis of toxin levels in wheat germ and wheat germ oil

A method consisting of solvent extraction using hexane for defatting, multifunctional cleanup column, and HPLC determination was validated for the analysis of deoxynivalenol (DON) and zearalenone (ZEA) in wheat germ and wheat germ oil. A total of 36 batches of grain wheat were subjected to industrial milling and the distribution factors in milled germ were 47% for DON and 71% for ZEA. A survey of 50 samples of germ-based dietary supplements revealed that 60% of wheat germ and 40% of wheat germ oils contained DON at mean values of 111 and 41 μg/kg, respectively, while none of germ samples and 16% oils contained ZEA (mean 6 μg/kg). Contamination levels lead to a daily intake of 1.3 μg DON and 0.03 μg ZEA, representing 1.9% and 0.23% of their respective tolerable daily intakes (TDI).     

同位素沾污面积的归位计算方法及其应用

在同位素吸水剖面测井中, 沾污给测量精度带来了较大的影响。文中分析了沾污类型及沾污消除校正系数, 根据吸水剖面中分配前的同位素沾污并不影响资料解释的结果, 分配之后的沾污破坏了地层注入量、同位素滤积量及放射性强度三者之间的正比关系, 以及影响分层相对注水量的解释精度这些特点, 介绍了沾污校正的沾污面积归位模型及计算方法, 并把该方法应用于资料解释中, 取得了理想的效果。     

Surveillance of nitrite level in cubilose: Evaluation of removal method and proposed origin of contamination

The discovery of nitrite contamination aroused public concern on the safety of cubilose consumption. Here, forty-eight batches of cubilose were randomly purchased from Hong Kong market. The median nitrite content of different types of cubilose was as follows: Red cubilose (600 ppm) > Yellow cubilose (510 ppm) ;> White cubilose (100 ppm). Under a developed standardized processing method, up to 98% of nitrite was removed from cubilose; nitrite was not detected in the stewed cubilose. To search for the source of nitrite, droppings from swiftlets and water samples were collected from production sites of cubilose in Malaysia and Indonesia, and which contained a high amount of nitrate. On the other hand, the protein extract of cubilose was subjected to proteomics analysis. A microbial nitrate reductase was identified by mass spectroscopy, which converted nitrate to nitrite in cubilose. A specific inhibitor of nitrate reductase successfully abolished the nitrate reduction activity found in cubilose, which subsequently reduced the nitrite in cubilose. This phenomenon was successfully proven by the field study. Thus, the nitrite on cubilose could be a result of the contaminating nitrate reductase.     

Multiple reaction monitoring of GC/MS/MS analysis of terpanes and its application to petroleum exploration

A highly sensitive and accurate multiplex gas chromatography–mass spectrometry–mass spectrometry (GC/MS/MS) technique and GC/MS technique are tested for terpanes in a hydrocarbon source rock sample. The terpanes, including tricyclic, tetracyclic, and pentacyclic, were quantified monitoring and identified with the transition m/z (262+14n)→191, 330→191, and (370+14n)→191 by multiple reaction monitoring of GC/MS/MS technique using collision energies of 5–30 eV. Results show that collision energies have great influence on tricyclic and pentacyclic terpanes' ratios. After comparing the analysis results by GC/MS, the collision energy for detecting terpanes using the MRM-MS/MS method is optimized at 23 eV.     

表面活性剂及其在石油污染土壤修复中的应用研究进展

石油的泄漏事故在油田勘探、开采和石油储存、运输、使用过程中时有发生,造成严重的石油污染。石油污染物中除了石油烃外,还含有多环芳烃,重金属等污染物,可对生态环境和人体健康造成危害。目前,处理石油污染土壤的方法主要有焚烧、热解吸、溶剂萃取、生物处理、热化学清洗等方法。由于石油烃类属于疏水有机物,黏附于土壤颗粒上,很难进行分离和降解,而表面活性剂能够促进疏水有机物的解吸和溶解,是一种有效、经济、有潜力的方法,并得到广泛的研究,本文重点介绍了表面活性剂的种类、在石油污染土壤修复中的应用和土壤吸附对表面活性剂效果的影响,提出了表面活性剂在石油污染土壤修复中的研究趋势和发展方向。     

频率域叠前波动方程反演及其应用

基于波动方程的叠前反演是地球物理反演的重要发展方向,它利用全波场信息反演的弹性参数对预测地下储层的含油气性有重要的参考价值。本文推导了频率空间域全波形反演公式,并将波动方程写成矩阵形式,反演过程中采用波场回传技术和可控共轭梯度算法来更新模型参数。推覆体模型试算结果表明,该方法适用于速度横向变化剧烈地质体,经过几十次迭代可以收敛到真实速度模型。在我国西部某气田实际资料应用表明,反演出的弹性参数与井数据吻合较好,能够为流体识别和储层含油气性预测提供可靠的地球物理参数。     

Zoeppritz方程的近似及其应用

本文提出以幂级数形式表示Zoeppritz方程近似公式。此式把纵波表示为射线参数p的偶次幂级数,把横波表示为射线参数p的奇次幂级数,它包含了目前广泛用于地震勘探的Aki和Richards公式,及Shuey公式。与前人的近似公式相比,本文提出的近似式具有形式简单、物理意义明确和岩性关系清晰等优点。此式有两个最显著的特征:第一个特征是易于识别和分离纵波和横波;第二个特征是幂级数项的系数A_n^R和A_n^T仅是介质的密度ρ、纵波速度α和横波速度β的函数,而幂级数的底则是入射角i的函数,幂级数的常数项A_n^R和A_n^T恰好是垂直入射时的反射系数和透射系数。所以利用曲线拟合方法很容易实现全部地震岩性参数的反演,并可提取零偏移距剖面。此外,利用此近似式可以得到一些以往已知的反射和透射规律,并能揭示一些新的反射和透射特征,还可以从常规的CDP道集记录中提取28种新的AVO特征剖面。     

断陷湖盆沉积作用的基本方程及其应用

湖盆沉积作用受气候、构造、沉积物供给条件、海平面升降变化等因素控制，将水深变化(水深加深为正值，水深变浅为负值)与盆地基底的沉降幅度(上升为负值，下降为正值)、绝对湖平面垂直变化(上升为正值，下降为负值)和沉积物厚度的关系浓缩为一个简单的沉积作用基本方程，其中各参数取某时间段内的变化值。结合对该基本方程及其各参数含义的讨论，综合解释湖盆层序界面的形成机制和湖退、湖进作用的原理。气候变化、构造抬升、断陷盆地中差异沉降运动等因素是控制层序界面形成的三大成因机制；根据湖退现象的作用机制，湖盆中也存在正常湖迟和强制湖退两种类型，沉积物过量充填引起湖盆发生正常湖退作用，相对湖平面下降导致湖盆发生强制性湖迟作用。图4参16     

煤层转换波的数值模拟及应用

从弹性波动方程出发，在交错网格空间中采用高阶有限差分技术导出了应力一速度弹性波动方程正演的差分格式，研究了其吸收边界条件与数值频散关系，建立了煤田多波勘探的数学模型。在此基础上通过对特定模型的数值模拟，研究了纵波震源激发条件下弹性波在地下的传播规律与煤层多波记录的波场特征。数值模拟结果表明，当地表不存在低速层时，煤田多波记录的X分量与Z分量上均有纵波与横波存在，因此在资料处理中必须首先进行波场分离工作。在一定的厚度范围内，煤层转换波的能量还与煤层厚度有关。故在进行野外资料采集观测系统设计时，要综合考虑转换波和纵波的观测范围。     

波动方程双参数反演方法及其应用

本文给出了用叠后资料反演一维波动方程双参数的理论和方法。通过模型的正,反演试算及抗噪试验,证实了该方法与算法的可靠性与可行性,并通过松辽盆地方３井实际资料的反演,得到了密度,波速两个独立的剖面。     

Antibacterial activity of Borago officinalis and Brassica juncea aqueous extracts evaluated in vitro and in situ using different food model systems

The present study was undertaken to characterize the antibacterial activity of the aqueous extracts (AEs) obtained from the leaves of Borago officinalis L. and Brassica juncea L. The antagonistic activity was evaluated against several bacteria (42 strains of Listeria monocytogenes, 35 strains of Staphylococcus aureus, 38 strains of Enterobacter spp. and 18 strains of Salmonella enterica) commonly associated with foodborne diseases by paper disc diffusion method. The susceptibility to the plant extracts was strain specific. Thirty-five strains (7 L. monocytogenes, 11 S. aureus, 1 S. Enteritidis, 1 S. Veneziana, 7 Enterobacter hormaechei, 5 Enterobacter cloacae, 1 Enterobacter sakazakii and 2 Enterobacter amnigenus) were sensitive to both AEs. The activity of B. juncea AE towards the Gram-positive strains was generally higher than that observed for B. officinalis (45 and 22 strains inhibited by B. juncea and B. officinalis, respectively), while an opposite trend was registered against the Gram-negative strains (22 and 35 strains inhibited by B. juncea and B. officinalis, respectively). The highest inhibition was displayed by B. juncea AE against E. sakazakii 23A. B. officinalis AE showed the same minimum inhibitory concentration (MIC) (10 mg/mL) for the majority of the most sensitive strains, while the MIC of B. juncea AE was different for each bacterial species and the lowest concentration was registered to inhibit enterobacteria (3.1 mg/mL). After 1-year storage in different thermal conditions (room temperature, 4 °C and −20 °C), both AEs lost their inhibitory power. The extracts did not show cellular toxicity when tested against sheep erythrocytes. Hence, B. officinalis and B. juncea AEs were effective as natural antibacterial substances. AEs were tested in situ in three food model systems (meat, fish and vegetable) at two concentrations, but only when added at a concentration 10-fold higher than that showing definite efficacy in vitro (100 and 31 mg/mL for B. officinalis and B. juncea, respectively), they inhibited the growth of the sensitive strains, even though the cells were still viable after 24 h. The influence of AEs on the volatile organic compounds (VOCs) composition of the food models was analysed by gas chromatography/mass spectrometry. The different levels of alcohols, aldehydes, esters, hydrocarbons, ketones and phenol registered, showed a consistent effect of B. officinalis and B. juncea AEs on the VOCs of the food models. However, the sniffing assay found only B. juncea AE impacting consistently the final aroma of the food models.     

新三水导电模型及其在低孔低渗储层评价中的应用

 本文通过在饱和度方程中引入与岩石性质有关的岩性系数a,发展了原三水模型,更加突出了三水模型在解决低孔低渗储层中的优势。新三水模型在比较全面地概括岩石几种不同导电机理的同时,也考虑了岩石性质的影响。将此模型应用于腰英台油田的低孔低渗储层和砂泥岩地层中,取得了较好的效果.