Determination of ochratoxin A in organic and non-organic cereals and cereal products from Spain and Portugal

The objective of this work was to know the occurrence of OTA in organic and non-organic cereals and cereal products from Spain and Portugal. A method based on extraction with matrix solid phase dispersion (MSPD) using octylsilica (C₈) followed by liquid chromatography coupled with fluorescence detection (LC–FD) was used to determine OTA from the selected samples. Recoveries of OTA from the studied samples spiked at 10 ng/g level ranged from 78% to 89% with a standard deviation of 3.66. The limits of detection and quantification of this method were 0.05 and 0.19 ng/g, respectively. Furthermore, LC–FD after OTA methylation was used to confirm the identity of OTA in all positive samples. This procedure was applied to 83 organic and non-organic samples including rice, wheat, barley, rye, oats and maize from Spain and Portugal. OTA was detected in 22% of the samples, with concentrations ranging from 0.20 to 27.10 ng/g. From the total OTA contaminated samples (n = 18), 72% were organic cereal and 28% were non-organic cereal samples, with mean concentrations of 1.64 and 0.05 ng/g, respectively. The 66% and 34% of contaminated samples were from Spain and Portugal, respectively, with mean concentrations of 0.93 and 0.64 ng/g for each country. Six contaminated samples exceeded the maximum limits (ML) for OTA fixed by European Commission Regulation (5 μg/kg), among them three were from Spain and three from Portugal.     

The method of the simultaneous determination of the citrinin and ochratoxin A content in cereals and cereal products

The simplifyed method of simultaneous determination of the citrinin (CT) and ochratoxin A (OTA) in cereals is described. The extraction of mycotoxins was carried out by small volumes of solvents (water/aceton/hexane) without additional sample clean up and concentration. The extracts were analysed by HPLC using mixture of methanol/ethylacetate/phosphoric acid, pH 2.2 as a mobile phase and fluorescence detection (lamda ex 330 nm, lamda em 495 nm). The reliability and reproducibility of results were improved by usage of internal standard--methyl-derivative of ochratoxin A. Average recovery of CT and OTA was 70%, relative standard deviation 12% and 7%, respectively, limit of detection 0.003 mg/kg.     

Superheated steam processing of cereals and cereal products: A review

The concept of superheated steam (SS) was proposed over a century ago and has been widely studied as a drying method. SS processing of cereals and cereal products has been extensively studied in recent years for its advantages of higher drying rates above the inversion temperature, oxygen-free environment, energy conservation, and environmental protection. This review provides a brief introduction to the history, principles, and classification of SS. The applications of SS processing in the drying, enzymatic inactivation, sterilization, mycotoxin degradation, roasting, and cooking of cereals and cereal products are summarized and discussed. Moreover, the effects of SS processing on the physicochemical properties of cereals and the qualities of cereal foods are reviewed and discussed. The applications of SS for cereal processing and its effects on cereal properties have been extensively studied; however, issues such as the browning of cereal foods, thermal damage of starch, protein denaturation, and nutrition loss have not been comprehensively studied. Therefore, further studies are required to better understand the mechanism of the quality changes caused by SS processing and to expand the fields of application of SS in the cereal processing industry. This review enhances the understanding of SS processing and presents theoretical suggestions for promoting SS processing to improve the safety and quality of cereals and cereal products.     

A review on ochratoxin A occurrence and effects of processing of cereal and cereal derived food products

Ochratoxin A (OTA) continues to grab global attention and concern for the hazard and impact that embody for both human and animals, based on its toxicity and occurrence. Despite OTA has been described in a myriad of foodstuffs, cereal and its derivatives remain the major contributors to OTA exposure. For that reason, a critical review on OTA occurrence reported by recent studies worldwide focusing on unprocessed and processed cereal foodstuffs is made in this work. Special attention is drawn to the major cereal derived products, namely flour, bread, breakfast cereals, baby/infant foods and the inherently involved technological food processing methods and its influence on the redistribution and chemical modification of OTA.     

Fusarium mycotoxins and ochratoxin A in cereals and cereal products: results from the Bavarian Health and Food Safety Authority in 2004

Results from the Bavarian Health and Food Safety Authority on contamination of cereals and cereal products from the Bavarian market with the mycotoxins deoxynivalenol (DON), zearalenone (ZEA), and ochratoxin A (OTA) and of maize meal and semolina with fumonisins (FUM) in the year 2004 are presented. Contamination rates and levels of DON, ZEA, and OTA were low and did not exceed the maximum levels. However, a 92% contamination rate and high levels of FUM in maize meal and semolina were measured. Contamination levels of mycotoxins are discussed and evaluated with respect to possible health implications for consumers.     

Determination of fumigants in cereals and cereal products by capillary gas chromatography

Summary This study describes two methods for the quantitative determination of the residual fumigants ethylene dichloride (EDC), carbon tetrachloride (CCl₄), trichlorethylene (TCE), ethylene dibromide (EDB) and tetrachlorethylene (PCE) in cereals (especially wheat) and other foodstuffs. In the first method, a micro steam distillation- solvent extraction apparatus is used, while the second method is based on a headspace technique. For the quantitative determination of carbon tetrachloride in cereals, the multiple headspace technique is not retained because it is too time-consuming. The analysis of the different fumigants is performed by electron-capture gas chromatography, using a fused silica capillary column, CP sil 8 CB. With the steam distillation-solvent extraction method, recoveries from 95.9% to 100.5% are obtained for the fumigants, added at two different levels. The standard deviation varies between 1.1 % and 6%. Using the simple headspace technique, recoveries from 73.5% to 85.1 % with a standard deviation of between 1.7% and 6.6% have been reached for the fumigants in cereals fortified at two different levels. The absulute detection limits for the five fumigants EDC, CCl₄, TCE, EDB and PCE, in both methods, are 30, 0.25, 1.1, and 0.5 pg, respectively.

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Bestimmung von Begasungsmitteln in Getreide und Getreideprodukten durch Capillar-Gaschromatographie

Zusammenfassung Es wurden zwei Methoden für die quantitative Bestimmung der Restmengen von Begasungsmitteln wie 1,2-Dichlorethan (EDC), Tetrachlorkohlenstoff (CCl₄), Trichlorethylen (TCE), 1,2-Dibromethan (EDB) und Tetrachlorethylen (PCE) im Getreide, insbesondere Weizen, und in Lebensmitteln beschrieben. Das erste Verfahren basiert auf einer Mikrodampfdestillation-Lösungsmittelextraktion, während für das zweite die Kopfraumtechnik verwendet wurde. Da mehrfache Kopfraum-Extraktion bei der Bestimmung des Tetrachlorkohlenstoffes in Getreide zu zeitraubend ist, wurde diese Methode nicht beibehalten. Die Begasungsmittel wurden durch Elektroneneinfang-Gaschromatographie unter Verwendung einer CP sil. 8 CB silica Glaskolonne bestimmt. Mit der Dampfdestillation-Lösungsmittelextraktion wird eine Ausbeute von 95,9 bis 100,5% für fünf Begasungsrestmengen in zwei verschiedene Konzentrationen erreicht. Die Standardabweichung varriiert zwischen 1,1 und 6%. Die einfache Kopfraum-Extraktion gibt für zwei verschiedene Konzentrationen eine Ausbeute von 73,5 bis 85,1% mit einer Standardabweichung von 1,7 bis 6,6%. Die absolute Nachweisgrenze beider Methoden für die fünf Begasungsmittel EDC, CCl₄, TCE, EDB und PCE ist 30, respektive 0,25, 1,1 und 0,5 pg.

     

Determination of fumigants in cereals and cereal products by capillary gas chromatography

This study describes two methods for the quantitative determination of the residual fumigants ethylene dichloride (EDC), carbon tetrachloride (CCl4), trichloroethylene (TCE), ethylene dibromide (EDB) and tetrachloroethylene (PCE) in cereals (especially wheat) and other foodstuffs. In the first method, a micro steam distillation- solvent extraction apparatus is used, while the second method is based on a headspace technique. For the quantitative determination of carbon tetrachloride in cereals, the multiple headspace technique is not retained because it is too time-consuming. The analysis of the different fumigants is performed by electron-capture gas chromatography, using a fused silica capillary column, CP sil 8 CB. With the steam distillation-solvent extraction method, recoveries from 95.9% to 100.5% are obtained for the fumigants, added at two different levels. The standard deviation varies between 1.1% and 6%. Using the simple headspace technique, recoveries from 73.5% to 85.1% with a standard deviation of between 1.7% and 6.6% have been reached for the fumigants in cereals fortified at two different levels. The absolute detection limits for the five fumigants EDC, CCl4, TCE, EDB and PCE, in both methods, are 30, 0.25, 1.1, and 0.5 pg, respectively.     

Sensitive method for the rapid determination of phytate in cereals and cereal products

A rapid method is described for the colorimetric determination of 1.5–15 μg phytate phosphorus in concentrations as low as 3 μg ml^?1 in extracts of cereal grains and cereal products. The phytic acid is precipitated with an acidic iron-III-solution of known iron content. The decrease of iron in the supernatant is a measure for the phyticacid content.     

Simultaneous determination of type A,B and D trichothecenes and their occurrence in cereals and cereal products

A sensitive LC–MS/MS method for the simultaneous determination of type A, B and D trichothecenes in cereals is presented. The limits of detection ranged between 0.1 and 0.7 µg kg^?1 for all analytes. The method was applied to 289 representatively drawn samples of wheat, rye and oat products. Ninety-four percent of the wheat samples (n = 130), 95% of the rye samples (n = 61) and 100% of the oat samples (n = 98) were contaminated with the type A trichothecenes T-2 and HT-2 toxin. Median levels of T-2/HT-2 (sum of the toxins) were 0.91, 0.53 and 8.2 µg kg^?1, respectively. Highest levels were found in wheat bran (24 µg kg^?1), rye kernels (3.1 µg kg^?1) and oat flakes (85 µg kg^?1). All wheat and rye samples and 75% of the oat samples were contaminated with the type B trichothecene deoxynivalenol. Median levels of this toxin were 23, 15 and 0.53 µg kg^?1, respectively. Highest levels were found in wheat bran (1160 µg kg^?1), rye kernels (288 µg kg^?1) and oat flakes (55 µg kg^?1). The type B trichothecene nivalenol was detected in 67% of the wheat samples, in 3% of the rye samples and in 24% of the oat samples with highest levels in wheat bran (96 µg kg^?1), rye kernels (1.8 µg kg^?1) and in oat flakes (17 µg kg^?1), respectively. Levels of other type A and B trichothecenes played a minor role, although the rates of contamination were often high. Neither macrocyclic type D trichothecenes (satratoxin G and H, verrucarin A, roridin A) nor diacetylverrucarol and verrucarol (type A trichothecenes), were detected in any of the samples.     

化学发光免疫分析方法检测粮食谷物中赭曲霉毒素A残留

目的建立粮食谷物中赭曲霉毒素A(ochratoxin A,OTA)残留检测的化学发光免疫分析方法。方法人工改造OTA半抗原、制备包被原和多克隆抗体工作液,优化检测步骤,验证各项评价指标,比较化学发光免疫分析方法和高效液相色谱法(high performance liquid chromatography,HPLC)的实际样本检测结果的一致性,以此来实现化学发光免疫分析方法的建立。结果 50%抑制浓度(IC_(50))为0.278μg/L;OTA的最低检出限为5.0μg/kg,样本添加回收率在65.4%到115.8%之间,批内、批间相对标准偏差15%。同时,通过对实际样本检测,证明化学发光免疫分析方法具有显著的准确度和可靠性。结论基于化学发光免疫分析方法能够实现粮食作物中的OTA残留的快速检测,灵敏度高、成本低、时间短,为食品中霉菌毒素残留的快速检测提供了新的技术参考。     

Occurrence of ochratoxin A and citrinin in Czech cereals and comparison of two HPLC methods for ochratoxin A detection

The aims of the study were to obtain information about the occurrence of ochratoxin A (OTA) and citrinin (CIT) in cereals harvested in the Czech Republic and to compare two analytical procedures for detecting OTA. A total of 34 cereal samples, including two matrix reference materials (R-Biopharm, Germany), were analysed. The results were compared with the limit for raw cereal grains used as a foodstuff according to Commission Regulation No. 1881/2006, which allows a maximum OTA level of 5 µg kg^?1. Compared were two methods based on the high-performance liquid chromatography principle, one using the immunoaffinity columns OchraTest? (VICAM) and the second based on solvent partition (PART), both followed by fluorescence detection. The highest OTA contents were found in two barley samples. According to the method employed, the results for the first sample (malting barley) were VICAM = 31.43 µg kg^?1 and PART = 44.74 µg kg^?1. For the second sample (feeding barley) they were VICAM = 48.63 µg kg^?1 and PART = 34.40 µg kg^?1. Two samples of bread wheat had an OTA content approaching the legal limit (VICAM = 4.71 µg kg^?1 and PART = 6.03 µg kg^?1; VICAM = 4.12 µg kg^?1 and PART = 3.95 µg kg^?1). CIT was analysed using the PART method only, and its highest content (93.64 µg kg^?1) was found for the malting barley sample with high OTA content (44.74 µg kg^?1 as analysed using PART).     

Performance of new clean-up column for the determination of ochratoxin A in cereals and foodstuffs by HPLC-FLD

The performance of the newly developed Mycosep® 229 Ochra and Multisep® 229 Ochra clean-up columns for ochratoxin A (OTA) determination was evaluated. OTA was subsequently analysed using RP-HPLC with fluorescence detection. Recoveries for frequently contaminated commodities, like cereals, red wine, raisins and green coffee, were estimated. The recoveries obtained for the Mycosep 229 Ochra column were in the range from 87.9 ± 12.5% (n = 6) for wheat to 99.4 ± 2.7% (n = 24) for raisins. For Multisep 229 Ochra, recoveries from 76.5 ± 8.0% (n = 6) for barley to 86.4 ± 1.4% (n = 24) for raisins were achieved. Limits of detection for all matrices investigated (maize, wheat, rice, barley, raisins, green coffee beans, red wine) were in the range 0.4-2.4 μg kg^-1. The trueness of the method was tested using a certified reference material.     

Aflatoxins and ochratoxin A and their Aspergillus causal species in Tunisian cereals

ABSTRACT

Occurrence of aflatoxins (AFs) AFB1, AFB2, AFG1, AFG2 and ochra toxin A (OTA) was studied in 65 samples of stored and freshly harvested wheat, barley and maize collected in Tunisia. The mycotoxins were simultaneously extracted and quantified by high performance liquid chromatography. Determination of AF-producing (section Flavi) and OTA-producing Aspergillus species (sections Nigri and Circumdati) was conducted in these samples by species-specific polymerase chain reaction (PCR). Results showed that most of maize samples were contaminated with AFs, data after storage showing lower values than those collected at harvest. All contaminated maize samples contained AFG1 and AFG2, among which 27.78% also had AFB1 and AFB2. This AFs pattern was consistent with the A. parasiticus toxin profile. A. flavus however showed the highest frequency in maize but was also found in barley and wheat where no AFs were detected. In contrast, OTA was neither found in maize nor in barley and only one wheat sample contained OTA. A. niger was the only OTA-producing species detected.     

Sensitive detection of ochratoxin A in wine and cereals using fluorescence-based immunosensing

Ochratoxin A (OTA) is a mycotoxin found in a wide range of food and feedstuffs. Intake of OTA-contaminated food causes health concern due to the harmful effects reported on humans and animals. Much effort is currently devoted to set up and optimise highly sensitive and accurate methods of OTA analysis. This work describes the comparison of fluorescence-based immunosensing strategies for the analysis of OTA. First, an indirect competitive fluoroimmunoassay was designed and optimised. The assay enabled the quantification of the toxin at the levels set by the European legislation. Then, a flow-immunoassay based on kinetic exclusion measurements was developed. It showed the theoretical lowest limit of detection enabled by the affinity of the anti-OTA antibody (IC(80)=12ngL(-1) in the assay solution). Wine and cereal samples were analysed using the optimised flow system. No significant matrix effects were observed after simple pre-treatment of wine and OTA extraction from corn-flakes samples. This simple and highly sensitive automated biosensing-system allows OTA quantification in food and beverages. It is envisaged as a powerful tool for rapid and reliable toxin screening.     

Sampling of cereals and cereal-based foods for the determination of ochratoxin A: an overview

The mycotoxin ochratoxin A (OTA) is known to be heterogeneously distributed both intrinsically (from one individual food item to the next) as well as distributionally (throughout a sample of individual food items) in cereals and cereal-based foods. Therefore, proper sampling and sample comminution are special challenges, but are prerequisites for obtaining sound analytical data. This paper outlines the issue of the sampling process for cereals and cereal-based foods, starting with the planning phase, followed by the sampling step itself and the formation of analytical samples. The sampling of whole grain and retail-level cereal-based foods will be discussed. Furthermore, possibilities to reduce sampling variance are presented.     

Feeding and egg-laying preferences of the sawtoothed grain beetle Oryzaephilus surinamensis: Beyond cereals and cereal products

The insect's response to various living substrates is an important determinant for their life history and demography reflected in their feeding and egg-laying preferences. However, research on polyphagous stored product insects such as the sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), are largely focused on cereal grains neglecting its alternative hosts. Therefore, this study examines the effect of a range of 16 host substrates including dry fruits, nuts, oil and legume seeds on insect development, survival, and adult emergence of the sawtoothed grain beetle, besides of also determining the feeding substrate weight loss. Overall, the feeding substrates exhibited a significant and different effect on O. surinamensis, except egg incubation time and length of the pupal period. The longest larval periods were observed on legumes followed by oilseeds and (dry) fruits. The highest survival and adult emergence were recorded on fruits and nuts, except raisin, but significantly lower than when fed on legume seeds, including soybean. The losses in fruits and nuts were higher, particularly on almonds and cashew. Larva development was inversely correlated to survival and adult emergence, which were positively correlated to substrate loss. Our study indicated that several non-grain commodities such as (dry) fruits and nuts are rather suitable substrates for the population growth of O. surinamensis, an additional concern for in international trade.     

On ochratoxin A and fungal flora in Polish cereals from conventional and ecological farms. Part 2: occurrence of ochratoxin A and fungi in cereals in 1998.

Over 200 samples of Polish cereal grain from the 1998 harvest obtained from conventional and ecological farms were investigated for the presence of ochratoxin A and for contamination by microscopic fungi. The frequency of contamination of rye and barley grains from conventional and ecological farms was similar in most cases; it varied from nearly 5 to 12%, respectively, for both types of farming. However, in samples from ecological farms, higher maximum concentrations of ochratoxin A were observed (35 micro g kg(-1), overall range 1.4-35.3 micro g kg(-1)) for both cereals rye and barley in comparison with rye and barley from conventional farms (maximum levels of 8.8 and 9.7 micro g kg(-1), respectively). However, wheat grain from the conventional farms showed ochratoxin A concentrations in a very wide range from 0.6 to 1024 micro g kg(-1) and the average frequency of contaminated samples was about 48%. In contrast, in wheat samples from ecological farming, the presence of ochratoxin A ranged from 0.8 to 1.6 micro g kg(-1) (mean 1.2 micro g kg(-1)) and the frequency of contamination was 23%. From samples containing detectable amounts of ochratoxin A, fungi producing ochratoxin A under laboratory conditions were isolated. They were classified as belonging to the species Penicillium cyclopium, P. viridicatum, Aspergillus ochraceus group, A. glaucus and A. versicolor. Penicillium strains-species known to be producers of ochratoxin A-were isolated from 71% of the samples; in 28% of samples, only Aspergillus strains (species known to be producers of this mycotoxin) were noted. These results have been compared with those obtained in 1997.     

On ochratoxin A and fungal flora in Polish cereals from conventional and ecological farms - Part 1: occurrence of ochratoxin A and fungi in cereals in 1997.

Over 200 samples of Polish cereal grain from the 1997 harvest obtained from conventional and ecological farms were tested for the presence of ochratoxin A as well as for contamination by microscopic fungi. Ochratoxin A contamination of rye from ecological farms was over six times more frequent than that from conventional cultivation. The ochratoxin A content in wheat and barley samples from ecological farms was also higher. No wheat sample from conventional farms contained the mycotoxin. In the group of ecological farms, there were differences in the percentage of cereal samples containing ochratoxin A. The ochratoxin A levels ranged from 0.2 to 57 microg kg(-1). The mean concentration of ochratoxin A in investigated cereal grain was 5.7 microg kg(-1). From samples containing detectable amounts of ochratoxin A, fungi producing ochratoxin A under laboratory conditions were isolated. They were classified as belonging to the species Penicillium cyclopium, P. viridicatum, P. chrysogenum and also Aspergillus alliaceus, A. versicolor, A. glaucus and A. flavus. Penicillium strains - producers of ochratoxin A - were isolated from 93% of the samples; in 7% of samples, only Aspergillus strains producing this mycotoxin were noted. Rye samples mainly from one farm with an ecological type of cultivation and from one conventional farm were contaminated with both Aspergillus and Penicillium mycotoxigenic strains.     

Trichothecenes, ochratoxin A and zearalenone contamination and Fusarium infection in Finnish cereal samples in 1998

The occurrences and concentrations of trichothecenes, ochratoxin A and zearalenone in Finnish cereal samples are presented in this study. Furthermore, infections by moulds, especially Fusarium contamination of grains in the same samples, are reported. In total 68 cereal samples, including 43 rye, 4 wheat, 15 barley and 6 oats samples, were collected after a cool and very rainy growing season in 1998. A gas chromatograph combined with a mass spectrometric detector was used for determination of seven different trichothecenes. A high performance liquid chromatograph with a fluorescence detector was used for ochratoxin A and zearalenone determination. For the identification of moulds, the grain samples were incubated and the moulds were isolated and identified by microscopy. The analytical methods were validated for mycotoxin analysis and they were found to be adequately reliable and sensitive. Heavy rainfalls in the summer and autumn of 1998 caused abundant Fusarium mould infection in Finnish cereals, particularly in rye. Fusarium avenaceum was the most common Fusarium species found in cereals. However, the mycotoxin concentrations were very low and only deoxynivalenol, nivalenol and HT-2 toxin were detected. Deoxynivalenol was detected in 54 samples in the concentration range 5-111 µg/kg. Nivalenol and HT-2 toxin were detected in three and two samples, respectively, in the concentration range 10-20 µg/kg.