Aflatoxins and ochratoxin A in Brazilian paprika

Seventy paprika samples collected in the city of São Paulo, Brazil, from January to April 2006 were analysed for aflatoxins and ochratoxin A (OTA) using an immunoaffinity column clean-up and HPLC-FLD. For aflatoxins, the limit of quantification (LOQ) were 0.23, 0.23, 0.45 and 0.45 μg/kg for AFB₁, AFB₂, AFG₁ and AFG₂, respectively. For OTA the LOQ was 0.80 μg/kg. Aflatoxins were found in 82.9% of samples and AFB₁ was detected in 61.4% at levels ranging from 0.5 to 7.3 μg/kg with mean concentration of 3.4 μg/kg. OTA was found in 85.7% at levels ranging from 0.24 to 97.2 μg/kg with mean concentration of 7.0 μg/kg.     

Aflatoxins and ochratoxin A in dried chestnuts and chestnut flour produced in Italy

The occurrence of aflatoxins and ochratoxin A in chestnut products made in Italy was surveyed. Thirty-seven samples of chestnut flour and fourteen of dried chestnuts were collected from retail outlets located in northern Italy. After extraction and purification through an immunoaffinity column, aflatoxins and ochratoxin A were analysed using both HPLC-FLD and HPLC-MS/MS. The mycotoxin contamination found in this survey was widespread and remarkable. As regards aflatoxins, the incidence of aflatoxin B₁ was 62.2 and 21.4% in chestnut flour and dried chestnuts, respectively; in the same products, the percentage of samples exceeding the value of 2.0 μg kg⁻¹ for aflatoxin B₁ (maximum limit fixed by EC Regulation 165/2010 in dried fruits) was 24.3% and 7.1%. A widespread and high incidence of AFG₁ was also found (40.5%). The maximum values for aflatoxin B₁ and total aflatoxins were 67.88 and 188.78 μg kg⁻¹, respectively (chestnut flour sample). Ochratoxin A occurred in all samples, showing very high values (mean 12.38 and 13.63 μg kg⁻¹ for chestnut flour and dried chestnuts, respectively); the percentages of samples exceeding the limit of 10 μg kg⁻¹ (EU limits for dried vine fruit) were 64.9 and 42.8% for chestnut flour and dried chestnuts, respectively. The maximum value was 65.84 μg kg⁻¹ (dried chestnut sample).     

Incidence of aflatoxins, ochratoxin A and zearalenone in tunisian foods

A total of 209 samples of different groups of foods widely consumed by the Tunisian population were collected during 2004–2005 years. Samples were analyzed for contamination with aflatoxins, ochratoxin A and zearalenone, using competitive enzyme-linked immunosorbent assay (ELISA). The predominant mycotoxin was ochratoxin A with a mean level of 3.5 ± 5.3 ng g⁻¹ in 59.8% of studied samples. Furthermore, Aflatoxins were detected in all analyzed commodities with a contamination frequency of 50.5%. In addition, aflatoxin B1 was found in 37% of the samples. The zearalenone was detected around 15% with a mean level of 10.4 ± 11.8 ng g⁻¹. Species, dried fruits and sorghum were the most contaminated samples by aflatoxin and ochratoxin mycotoxins, whereas Rice was the least contaminated commodity. The most frequent mycotoxins co-occurrence included aflatoxins and ochratoxin A, which have been detected in 33.8% of analyzed samples. Furthermore, the simultaneous contamination by aflatoxins, ochratoxin A and zearalenone was observed in 7.2% of studied samples.     

Study of Saccharomyces cerevisiae W13 as a functional starter for the removal of ochratoxin A

In this paper, a wild strain of Saccharomyces cerevisiae (W13) was studied for its OTA-removal ability, growth pattern and alcoholic fermentation profile at two different temperatures (25 and 30 °C) and two different sugar levels (200 and 250 g l⁻¹), with or without supplementation of medium with diammonium phosphate (DAP). A commercial strain (Lallemand EC1118) and a collection isolate (DBVPG 6500) of S. cerevisiae were also studied. All the strains were able to conclude fermentation, with S. cerevisiae W13 producing higher ethanol and glycerol contents; moreover, the wild strain was able to remove OTA (reduction of 6–57.21%), with the highest removing effect observed at 30 °C with 250 g l⁻¹ sugar and after 3 days.In addition, S. cerevisiae W13 was studied for its technological and qualitative traits, as it showed a high tolerance to single and combined stress conditions, β-d-glucosidase, pectolytic and xylanase activities, a low level of hydrogen sulphide production, a low-to-medium parietal interaction with phenolic compounds and no biogenic amines formation.The findings of this work have an applicative value for the potentiality of using S. cerevisiae W13 as functional starter for the production of wines with improved qualitative and food safety characteristics.     

Effect of sulfur dioxide and ethanol concentration on fungal profile and ochratoxin a production by Aspergillus carbonarius during wine making

Fungal profiles and ochratoxin A (OTA) accumulation during wine making were investigated using five different wine grape cultivars, Cabernet Sauvignon, Pinot Noir, Merlot, Syrah and Petit Verdot and the intrinsic influences caused by sulfur dioxide, ethanol and combine effect of ethanol and reducing sugar were analyzed using Cabernet Sauvignon and inoculation of Aspergillus carbonarius. Aspergillus spp. and Penicillium spp. were found as the major fungi in all winemaking processes and were highly correlated with OTA accumulation in wine. Most fungi died and OTA production decreased after 48 h of alcoholic fermentation, being consistent with the period when ethanol accumulation increased. The addition of SO₂ significantly inhibited the growth and OTA production of A. carbonarius with complete inhibition at 500 mg/L. When the ethanol concentration in the must increased to the range of 2–4%, growth and OTA production of A. carbonarius were significantly inhibited. Reducing sugar concentration had no significant effect on the growth and OTA production of A. carbonarius within the levels changing during the winemaking. Therefore, the increase of ethanol concentration played an important role in causing the decrease of fungal contamination and OTA accumulation during winemaking.     

A simple and rapid biosensor for ochratoxin A based on a structure-switching signaling aptamer

A fast and reliable sensing platform has been developed for the detection of mycotoxin ochratoxin A (OTA) based on a target-induced structure-switching signaling aptamer. In the absence of target, a fluorescein-labeled OTA aptamer hybridizes to a complementary DNA strand containing a quencher moiety, bringing the fluorophore and the quencher into close proximity for highly efficient fluorescence quenching. Upon OTA addition, a conformational change in the aptamer releases the quencher-containing DNA strand, generating a strong concentration-dependent fluorescent signal. Using this technique, the entire detection and analysis process of OTA can be completed within 1 min. Under optimized assay conditions, a wide linear detection range (from 1 to 100 ng/mL) was achieved with a detection limit down to 0.8 ng/mL. Additionally, the proposed assay system exhibited high selectivity for OTA against other mycotoxins (aflatoxin B₁ and zearalenone) and limited interference from the structural analog ochratoxin B. The biosensor was also applied to a non-contaminated corn material spiked with a dilution series of OTA, obtaining recoveries from 83% to 106%. Utilization of the proposed biosensor for quantitative determination of mycotoxins in food samples may provide significant improvements in quality control of food safety through a simple, rapid, and sensitive testing system for agricultural products monitoring.     

Effect of different roasting levels and particle sizes on ochratoxin A concentration in coffee beans

Contamination of roasted coffee with ochratoxin A (OTA) is directly related to the processing quality throughout the coffee production chain, from the farming to the roasting processes. The aim of this study was to evaluate the effects of roasting and particle size on the residual concentration of ochratoxin A in roasted and ground coffee. Coffee beans were artificially contaminated with Aspergillus ochraceus. The beans were roasted to three levels (light, medium and dark) and ground into three types (fine, medium and coarse) after an incubation period. OTA quantification was performed using high-performance liquid chromatography. The combination of dark roast and coarse particle size had the lowest concentration of OTA, 3.06 μg/kg with a 97.17% reduction. The results of this study show that roasting and particle size, rather than roasting alone, are critical for the residual concentration of OTA in roasted and ground coffee beans.     

Occurrence of ochratoxin A in cereal-derived food products commonly consumed in Turkey

Ochratoxin A (OTA) is a mycotoxin that can be found in several food commodities including cereals, wine, coffee, cacao, spices or dried fruits, resulting in chronic human exposure. The aim of our study was to investigate the presence of OTA in widely consumed cereal-derived products commercialized in Turkey. A total of 142 samples were collected from different supermarkets and traditional bazaars in Istanbul during 2008-2010 years. The analytical methods used in our study involved the liquid/liquid extraction of OTA, immunoaffinity clean-up and high performance liquid chromatography determination with fluorescence detection. The frequencies of OTA contamination were 21.62%, 19.05% and 55.95% and the mean concentrations of positive samples were 0.32 μg/kg, 0.14 μg/kg, 0.41 μg/kg for breakfast cereals, cereal-based baby foods and tarhana samples, respectively. Our findings show that contamination levels of OTA in all cereal-derived products were lower than the permitted level by European Commission Regulation.     

A comparative study of DNA extraction methods to be used in real-time PCR based quantification of ochratoxin A-producing molds in food products

Quantification of ochratoxin A (OTA)-producing molds in foods by real-time quantitative PCR (qPCR) may be affected by the DNA extraction method used. In the present work, 6 different methods for extraction of DNA from ochratoxigenic molds in foods were tested. Several combinations of mechanical and thermal lysis of conidia with commercialized DNA extraction kits and enzymatic treatments or resins were evaluated. DNA recovery and quality of extracted DNA was measured by testing the extracted DNA with a conventional PCR and an SYBR Green qPCR amplifying the β-tubulin gene and the non-ribosomal peptide synthetase gene, otanpsPN. Inhibition of conventional and qPCR was not observed when the DNA-extraction method includes an initial thermal disruption of conidia before use of commercialized extraction kit or resin, enzymatic treatment and/or lysis buffer. Of the six methods tested, the one combining thermal lysis of conidia followed by a short enzymatic treatment and incubation with Chelex-100 resin and final extraction with the EZNA kit was selected, since the extracted DNA showed good amplification by conventional PCR for β-tubulin gene and the highest DNA recoveries when tested by qPCR. The method was subsequently validated in different food products such as ripened foods, nuts, and grapes inoculated with Penicillium and Aspergillus species. With this Chelex100-enzymatic-EZNA method good DNA recoveries ranging from 69 to 99% were obtained for all food matrices and fungal species tested. This fast method is a promising tool to be used as routine analysis in HACCP systems in the food industry for quantifying OTA-producing molds by qPCR.     

Co-occurrence of aflatoxins and ochratoxin A in cereal flours commercialised in Turkey

In this study, we aim to determine co-occurrence of aflatoxins (AFs) and ochratoxin A (OTA) in cereal flours commercialised in Corum, Turkey. One hundred cereal flours were checked for target fungal metabolites between the years 2011 and 2013. The samples were analysed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD) after immunoaffinity column (IAC) clean-up procedure. The method was successfully validated in accordance to European Union guidelines acceptance criteria for specificity, linearity, sensitivity, trueness and repeatability. All the results are well below the maximum limits specified in the EU legislation. AFs were detected neither wheat flour nor rice flour samples, while 66.7% of maize flours contained AFs with maximum concentration of 1.12 μg kg⁻¹. OTA was present in 26.7% of wheat flour, 41.7% of maize flour and 18.8% of rice flour samples, with mean levels of 0.247, 0.218 and 0.154 μg kg⁻¹, respectively. The co-occurence of AFs and OTA was found in 9 maize flour samples.     

The development of an activated carbon from cherry stones and its use in the removal of ochratoxin A from red wine

The ability of activated carbon (AC) prepared from cherry stones (CS) by activation with H₃PO₄, ZnCl₂ or KOH to remove ochratoxin A (OTA) from two Italian red wines has been studied. AC was characterized in terms of texture and surface chemistry. OTA was analyzed by reversed-phase high-performance liquid chromatrography, using a fluorescence detector. The content of OTA in the starting wines is 7.38 and 2.36 μg/L. The adsorption of OTA is high only for one AC, which was prepared by KOH activation at 900 °C, using the 3:1 KOH:CS impregnation ratio. It possesses a large apparent surface area (S_BET = 1620 m²/g) and a high volume of large size macropores (1.84 cm³/g). It also contains narrow mesopores and intermediate size and wide micropores. Its content of acidic oxygen surface groups is low, whereas the content of basic groups is high (2.62 meq/g). The treatment of the wines with such an AC results in a decrease of the initial OTA content of more than 50%. However, the changes produced in the total polyphenolic index, color intensity, and hue are small (i.e. ～8%, ～5.5% and ～1.2%, respectively).     

新型阻聚剂EC3144A在乙烯生产中的应用

简要介绍了裂解气压缩机的结垢机理和新型阻聚剂ＥＣ３１４４Ａ的阻聚机理,并使用Ｎ因子对ＥＣ３１４４Ａ在大庆乙烯装置裂解气压缩机上的应用情况进行了和分析。结果表明,ＥＣ３１４４Ａ的应用具有明显的阻聚效果和良好的经济效益。     

双酚A合成中副产物的裂解反应工艺研究

对双酚A合成工艺中副产物的裂解反应过程进行研究,确定了催化剂种类及用量,考察了各种因素对裂解反应的影响,获得了较佳工艺条件;并对裂解反应器形式进行了对比实验研究,结果表明,采用内衬复合金属丝网的降膜反应器比传统的釜式裂解反应器具有明显的优势。     

Incidence of microorganisms from fresh orange juice processed by squeezing machines

This study was carried out to evaluate the microbiological quality of orange juice obtained from squeezing machines in foodservice establishments. The samples included fresh squeezed orange juice and juice which is maintained in metal jugs until consumption. According to the European Commission Regulation (No. 2073/2005 and No. 1441/2007) and Spanish microbiological criteria (No. 3484/2000), 12% and 43% of the total examined lots exceed the adopted limits of mesophilic aerobic counts and Enterobacteriaceae, respectively. Possibly, this contamination is caused by incorrect handling of oranges and juices and also by inadequate cleaning and sanitization of squeezing machine and metal jugs. Furthermore, 0.5 and 1% of all the examined lots were positive for the presence of Salmonella spp. and Staphylococcus aureus, respectively. However all lots were negative for Escherichia coli and Listeria monocytogenes. These results emphasize the need for applying and maintaining good hygienic practices in the restaurants.     

美国PMC公司管加工机床的技术特点

从设计原理，结构和性能等方面分析了美国ＰＭＣ公司制造的这车丝机，接箍车丝机，切管机和接箍切断机等主要石油专用管材加工机床的技术特点，在概托其先进性的同时，也指出其存在的不足之处。     

Development of a sensitive competitive indirect ELISA method for determination of ochratoxin A levels in cereals originating from Nanjing,China

A monoclonal antibody against ochratoxin A (OTA) was produced and a simple, rapid and reliable competitive indirect ELISA (ci-ELISA) for detection of OTA was developed. The 50% inhibitory concentration (IC₅₀) was 1.70 ng/mL, with a detectable range of 0.55–6.75 ng/mL, and a limit of determination (LOD) at 0.15 ng/mL. The cross-reactivity of the antibody against ochratoxin B was 17%, and <10% against deoxynivalenol, fumonisin B₁ or aflatoxin B₁. A survey of 65 cereal samples was carried out in Nanjing, the capital of Jiangsu Province, China. The frequencies of OTA contamination were 36.36%, 26.08% and 15.00%, and the mean concentrations of positive samples were 4.248 ng/g, 7.360 ng/g and 3.382 ng/g for wheat, corn and rice, respectively. The results of this study suggest that the ci-ELISA developed can be used to determine OTA in agricultural commodities such as cereals, and a survey might be needed to investigate OTA contamination in food and feed to prevent their harmful health effects.     

分支水平井排水采油中排水量的确定方法

为了控制强底水薄层油藏中水平井的含水率,常常采用分支井排水方法。研究发现该方法要取得明显的控水效果就需要确定合理的排水量,由于目前没有相关的理论公式,为此进行了研究。首先假设地层为均质,考虑油水两相,油水渗流满足达西定律,忽略流体的压缩性;假设底水为无限大水体,采油井位于油水界面上部,排水井位于油水界面下部,建立渗流微分方程。根据瞬时点源解和叠加原理,分别求解出采油井和排水井的产量公式,从而进一步反求得到采油井和排水井生产时所需的压差,根据压差与油水界面的平衡关系推导出排水量与排水井距离油水界面的位置之间的函数关系,从而得到最优的排水量求解公式。该公式表明,顶部分支井的产油量、油水流度比以及油水界面的位置是影响最优排水量的主要因素。     

Effects of the processing steps on chlorpyrifos levels during honey production

The effects of different steps in honey production on chlorpyrifos levels were investigated. Chlorpyrifos residues were quantified by gas chromatography with flame photometric detection (GC-FPD) after each stage including preheating, filtration, vacuum concentration and pasteurization. The total loss of chlorpyrifos in honey was about 70% during the processing. Among these four stages, filtration and vacuum concentration had the significant effects on chlorpyrifos level, and the mean losses were 21.3 and 60.9, respectively.