Survey for co-occurrence of ochratoxin A and aflatoxin B1 in dried figs in Turkey by using a single laboratory-validated alkaline extraction method for ochratoxin A

A survey was carried out to determine the co-occurrence of ochratoxin A and aflatoxin B1 in dried figs from Turkey. Samples from two seasons of crops (2003 and 2004) intended for export to the European Union and the 2004 crop obtained from the domestic Turkish market were analyzed. Affinity column cleanup methods were employed for determining separately ochratoxin A and aflatoxin B1, but for ochratoxin A an alkaline extraction procedure was employed (in contrast to the conventionally employed acidic extraction), which gave consistently higher toxin recovery. In-house validation of the ochratoxin A method gave a limit of detection of 0.15 ng/g and a limit of quantification of 0.5 ng/g with a repeatability of 5.8% in the range 5 to 10 ng/g (with a mean recovery of 94% for spiked samples). Positive results for ochratoxin A were confirmed by liquid chromatography-mass spectrometry. For the 2003 export figs (58 samples), 7 samples contained only aflatoxin B1, 2 samples contained only ochratoxin A, and 2 samples contained both toxins (with maximum concentrations of 35.1 ng/g for aflatoxin B1 and 13.0 ng/g for ochratoxin A). Similarly for the 2004 export figs (41 samples), 16 samples contained only aflatoxin B1, 4 samples contained only ochratoxin A, and 2 samples contained both toxins (with maximum concentrations of 20.6 ng/g for aflatoxin B1 and 26.3 ng/g for ochratoxin A). Of 20 retail samples of dried figs from Turkey, only one sample contained ochratoxin A (2.0 ng/g) and none were contaminated with aflatoxin B1. This survey revealed a 14 to 15% incidence of occurrence of ochratoxin A for 2 years, which is higher than previously reported.     

胶体金免疫层析法检测酱油中黄曲霉毒素B1

采用胶体金免疫层析法检测酱油中的黄曲霉毒素B1。加标的酱油样品经提取后,以胶体金免疫层析法对其进行黄曲霉毒素B1测定,并与酶联免疫吸附法进行比较。结果表明,当酱油中黄曲霉毒素含量超过国家限量标准(5μg/kg),胶体金免疫层析法检测结果为阳性,说明该方法能够满足酱油样品中黄曲霉毒素B1监控的要求。     

高特异性黄曲霉毒素B_1单克隆抗体的制备及特性研究

本研究将黄曲霉毒素B1转化为半缩醛B2a,在硼氢化钠（NaBH4）还原作用下与载体蛋白偶联制备完全抗原。将制备的完全抗原免疫Balb/c小鼠,经4次免疫后取其脾脏与小鼠骨髓瘤细胞Sp2/0细胞融合,采用半固体培养基筛选后鉴定,获得杂交瘤细胞株3A12,抗体的灵敏度可达6.1±0.025ng/mL,抗体与其它黄曲霉毒素B2、G1及G2的交叉反应率依次为7.8%、20.2%及0.6%,与黄曲霉毒素M1交叉反应率小于0.1%。本研究为研发花生等农产品黄曲霉毒素B1特异性免疫分析技术及产品奠定了重要基础。     

Determination of aflatoxin B1 in dried figs by visual screening, thin-layer chromatography and ELISA

Aflatoxin B1-contaminated fruits were sorted out from 250 kg dried figs (five Turkish and three Greek batches) by bright-greenish-yellow fluorescence under UV light. The aflatoxins of the fluorescent figs were extracted by simple soaking in methanol. Aflatoxin B1 was determined by thin-layer chromatography. Parallel to this, an extraction for the determination of aflatoxin B1 was developed by a competitive ELISA and the two methods were compared with each other. In a highly contaminated batch of Turkish figs, statistically there was one fig among 350 which had a high aflatoxin content (greater than 100 ng/g fig) and one fig amongst 140 fruits with an aflatoxin B1 content of greater than 10 ng B1/g fig.     

Occurrence of aflatoxin in commodities imported into Qatar, 1997-2000.

The occurrence of aflatoxin in commodities imported into Qatar was investigated from 1999 to 2000. During the 4 years, 351 samples of susceptible commodities were analysed. Aflatoxin was detected in 71 (20%) samples in the range 0.1-20 microg kg(-1) and in 50 (14%) samples above the permitted level of 20 microg kg(-1). The highest incidence and levels of aflatoxin contamination were recorded in pistachio without shell followed by pistachio with shell. Aflatoxin levels >20 microg kg(-1) in the pistachio samples varied from 8.7 to 33%. The highest level of total aflatoxin found in pistachio without shell was 289 microg kg(-1). A few samples of corn and corn products (three of 54 analysed), peanut and peanut products (nine of 42 analysed) and other nuts like almond, walnut and cashew (one of 40 analysed) were found contaminated with low levels (0.1-20 microg kg(-1)) of aflatoxins. Only one sample of custard powder and one sample of roasted peanut were found with aflatoxin >20 microg kg(-1)     

Aflatoxin M1 occurrence in dairy products marketed in Italy

In 1984, 313 samples of imported liquid milk and 159 samples of imported cheese were checked for aflatoxin M1; 225 of the milk samples came from FR Germany and 88 from France, while 82 of the cheese samples came from France, 34 from FR Germany and 43 from the Netherlands. The number of positive samples was small both for German (13.8%) and for French (12.5%) milks, and the contamination levels were very low (maximum 23 ng/l). As regards the cheeses, aflatoxin M1 was detected in 19.5, 26.5 and 53.5% of the French, German and Dutch samples respectively, but only 2 French samples exceeded 250 ng/kg, the limit set by Swiss law. In 1985, two surveys were carried out on 276 milk samples mostly obtained from individual farms and on 416 cheese samples taken from all parts of the country. As regards the milk samples, 70 (25.3%) contained aflatoxin M1, but generally at very low levels; in fact only 7 (2.5%) of the samples exceeded 50 ng/l. Aflatoxin M1 was found in 130 (31.3%) of the cheese samples, but here again only 9 (2.2%) exceeded 250 ng/kg. There was no significant difference in aflatoxin M1 levels between Italian, German and French cheese samples but these were significantly lower (P less than 0.01) than in Dutch samples.     

Co-occurrence of aflatoxin B1, fumonisin B1, ochratoxin A and zearalenone in cereals and peanuts from C?te d'Ivoire.

This survey examined 30 samples of rice (n = 10), maize (n = 10) and peanuts (n = 10) from C?te d'Ivoire for aflatoxin B1, fumonisin B1 and zearalenone using immunoassays, and ochratoxin A using a validated HPLC method with fluorescence detection. In C?te d'Ivoire, as in other countries, several mycotoxins are present in the same commodities. These mycotoxins are from different structural families: aflatoxin B1, fumonisin B1, zearalenone and ochratoxin A, normally produced by fungal species from Aspergillus, Penicillium and Fusarium genera. Some samples contained four mycotoxins (86%). Four peanuts samples did not show ochratoxin A (14%), whereas they contained aflatoxin B1 concentrations above the EU regulatory limits. Concentrations of ochratoxin A, zearalenone and fumonisin B1 were low and may not cause problems per se; however, fears remain that the tolerable daily intake may be exceeded due to eating habits and synergistic effects could be important with the combination of several mycotoxins. Investigations in this direction are underway, together with isolation and characterization of the fungal species involved.     

高效液相色谱-柱后光化学衍生法测定油茶中黄曲霉毒素B1的方法研究

目的建立高效液相色谱-柱后光化学衍生法测定油茶中黄曲霉毒素B_1含量的方法。方法市售油茶样品粉碎,经80%甲醇-水溶液涡旋提取、离心,吸取上清液稀释,专用免疫亲和柱净化后,采用高效液相色谱荧光检测器串联光化学衍生器测定黄曲霉毒素B_1。同时,对样品提取条件的选择、样品净化过程、流动性比例选择等进行优化实验研究。结果黄曲霉毒素B_1在0.5～20 ng/mL范围内线性关系良好,相关系数r=0.9996,在5、10、20μg/kg添加水平下的回收率为84.0%～91.6%,相对标准偏差0.1%～1.7%。结论该方法简单、快速、准确、重现性好,适用于油茶中黄曲霉毒素B_1的定量分析。     

Aflatoxin M1 in yoghurts in Portugal

Aflatoxin M1 (AFM1) may occur in milk and milk products, resulting from the ingestion of aflatoxin B1 in feedstuffs by dairy cow. Ninety-six samples of commercial yoghurts (48 natural yoghurts and 48 yoghurt with pieces of strawberries) that are produced in Portugal were analyzed for the presence of AFM1 by immunoaffinity column extraction and high-performance liquid chromatography (HPLC). The limit of detection was 10 ng/kg. The recoveries of AFM1 from the samples spiked at levels of 10.0, 50.0, 100.0 and 150.0 ng/kg were 88.0%, 91.0%, 93.0% and 99.0%, respectively. AFM1 was detected in 18 (18.8%) of yogurt samples ranging from 19 to 98 ng/kg, and 78 samples (81.2%) did not reveal the presence of the toxin. Of the 48 natural yoghurts tested, only two (4.2%) were contaminated with 43 and 45 ng/kg of AFM1. Of the 48 yoghurts with pieces of strawberries tested, 16 samples (33.3%) contained levels ranging from 19 to 98 ng/kg; six samples (12.5%) were contaminated with low levels ranging from 19 to 35 ng/kg; four samples (8.3%) were contaminated with levels ranging from 36 to 50 ng/kg, two samples (4.2%) with levels of 51 and 65 ng/kg and four samples (8.3%) presented high contamination levels, from 90 to 98 ng/kg. This paper reports the data of the first survey on the presence of AFM1 in yoghurt in Portugal.     

Methods for determination of aflatoxin M1 in milk and milk products--a review of performance characteristics

Among numerous methods that have been published for determination of aflatoxin M1 in milk and milk products, the following have been selected for review of performance characteristics: methods for which interlaboratory testing has been carried out, methods proposed in support of national (Swiss) regulations following inclusion in check sample series, and methods that report detection limits for milk of less than or equal to 5 ng/l (less than or equal to 0.005 microgram/l) or less than or equal to 10 ng/kg (less than or equal to 0.01 microgram/kg) for cheese. It is practical to determine aflatoxin M1 in milk with good accuracy and precision down to low ng/l concentrations using thin-layer chromatography, high-performance liquid chromatography or enzyme-linked immunosorbent assay for quantitation. However, measurement at such low levels has not been tested by a true collaborative study. Confirmation of identity of aflatoxin M1 at low ng/l levels has also been reported. Recent evidence suggests that consideration should be given to inclusion of aflatoxin M4 in methods for aflatoxin M1.     

Survey of aflatoxin contamination of dried figs grown in Turkey in 1986

A total of 284 dried fig samples, collected from fields during drying, and from warehouse and processing units in the Aegean region of Turkey in 1986, were examined for aflatoxin contamination. Aflatoxin B1, B2, and G1 were detected in 4, 2, and 2% of the samples, respectively, which were of the lower grade of figs taken from the drying stage. The average alfatoxin levels in positive samples were estimated to be 112.3 (B1), 50.6 (B2), and 61.4 ng/g (G1). The samples collected from storage (64 samples) and processing units (14 samples) contained no aflatoxins. The results of this survey show that aflatoxin contamination of Turkish dried figs in 1986 was highly correlated with the poorer grade of fig.     

A survey of the incidence and level of aflatoxin contamination in a range of imported spice preparations on the Irish retail market

The aflatoxin contents of 130 commercial spice preparations, including pepper, chilli, curry powder, cayenne, paprika, cinnamon, coriander, turmeric and cumin, were determined using high performance liquid chromatography (HPLC). Samples were obtained from various retail outlets in Ireland, including supermarkets, shops and market stalls. Aflatoxin B1 gave the highest incidence of contamination in spice preparations and was found in 20 of the 130 samples. The highest concentration of aflatoxin, 27.5 μg/kg, was detected in a sample of chilli powder; next highest was in a sample of cayenne pepper which contained 18.5 μg/kg. Five samples (3.8%), consisting of chilli, cayenne pepper and turmeric pepper, were above the regulatory limits of the European Union. Aflatoxin contamination was not detected in cumin or cinnamon samples at a level of quantitation (LOQ) <0.2, <0.1, <0.5, <0.3 μg/kg for B1, B2, G1 and G2, respectively.     

Detection and quantitation of aflatoxin B1 in orange juice by SOS-Chromotest

A new method for the detection and quantitation of aflatoxin B1 in liquids is described. The method is based on the SOS Chromotest, in which damage caused by aflatoxin B1 to the DNA of suitably engineered E. coli induces beta-galactosidase. Aflatoxin B1 developing in orange juice inoculated with spores of Aspergillus parasiticus is detectable equally well by TLC as by the SOS-Chromotest.     

Co-occurrence of aflatoxins B 1 , B 2 , G 1 , G 2 , zearalenone and fumonisin B 1 in Brazilian corn

Two hundred and fourteen unprocessed corn samples (1997-98 harvest), collected at wholesale markets in different regions in Brazil, were surveyed for the occurrence of mycotoxins. The samples were analysed for aflatoxins B 1 , B 2 , G 1 , G 2 , zearalenone and fumoni1sin B 1 using in-house validated methods. The occurrence of aflatoxin B 1 , zearalenone and fumonisin B 1 was found in 38.3, 30.4 and 99.1% of the samples, respectively. Aflatoxin B 1 , zearalenone and fumonisin B 1 contamination levels varied from 0.2 to 129, 36.8 to 719, and 200 to 6100 μg/kg, respectively. The cooccurrence of the two carcinogenic mycotoxins aflatoxin B 1 and fumonisin B 1 was observed in 100% of the aflatoxin-contaminated samples (82 samples). Cooccurrences of aflatoxin B 1 : zearalenone: fumonisin B 1 and aflatoxin B 1 : aflatoxin B 2 : fumonisin B 1 were found in 18 and 43 samples, respectively.     

Occurrence of aflatoxins (B1, B2, G1, G2) in herbal tea consumed in Turkey

Aflatoxin contents in 12 types of herbal teas were determined by high performance liquid chromatography (HPLC) with fluorescence detector using immunoaffinity column clean-up. Forty eight samples were collected from four local herbal shops in Manisa, Turkey. Of the 48 samples analyzed, 43 were aflatoxin positive. The highest concentration of aflatoxin (34.18 µg/kg) was determined in a sample of camomile tea. The occurrence of AFB1, B2, G1 and G2 was found in samples at levels of 54, 29, 71 and 46 %, respectively. Aflatoxin B1, B2, G1 and G2 contamination levels varied from 0 to 14.2, 0 to 12.4, 0 to 13.5 and 0 to 28.7 µg/kg, respectively. Aflatoxin was not detected in five samples consisting of linseed, lime and fennel tea.     

Aspergillus flavus and aflatoxin production in acid-treated maize

Isobutyric acid (IBA) and propionic-acetic acid (PA) were applied to comparable 52.8 m³ lots of freshly harvested yellow dent maize containing 27% moisture. After 6 months storage, 30% Aspergillus flavus infection and low levels of aflatoxin were detected in adjacent bins of IBA-treated and PA-treated maize. Extensive samples were taken after 7 months from moldy spots in each bin and evaluated for aflatoxin, zearalenone, ochratoxin and microorganisms. Aspergillus flavus (10⁶ propagules/g) was detected in 40% of the PA samples, but no aflatoxin was found. Also, counts of Aspergillus fumigatus, Absidia and Penicillia were high. In addition to the molds found on PA maize, Aspergillus niger was identified on IBA-treated maize. Aspergillus flavus (10⁴–10⁷ propagules/g) was present in 79% of the IBA samples; aflatoxin (from 2 to 857 ng/g) was detected in 57%. Aflatoxin contamination varied between locations within a moldy area. Among 20 individual kernels picked at random from each location, aflatoxin contamination ranged from 150 to 21.800 ng/g in positive kernels. Evidently, bulk quantities of maize must be appraised on the basis of individual kernels because toxin-free kernels often are adjacent to highly contaminated kernels.     

Stability of aflatoxin M in milk.

This three-part study was designed to determine aflatoxin M recovery from pasteurized and/or stored cow's milk. (a) Aflatoxin M was added to samples of raw Holstein milk at a concentration of 2.0 mug/liter. Half of each sample then was pasteurized at 63 C for 30 min, and both raw and pasteurized portions were stored at 4 C up to 17 days. (b) Samples of raw milk, pasteurized (77 C, 16 s) skim milk, dry cottage cheese curd, and cottage cheese whey were taken from a commercial operation in an area in which natural contamination had been encountered. (c) Milk from a cow dosed with aflatoxin B1 was stored frozen (-18 C) in bulk and in assay-size sample containers for 120 days. Aflatoxin M was recovered completely after either storage or pasteurization in (a) and (b). In (c), a recovery deficiency was detectable after 68 days of storage, which increased to 45% of the original value by 120 days. These observations differ from those of others in that loss of aflatoxin M was significant after pasteurization or storage of raw milk, totaling 87% loss after 120 days of frozen storage. Aflatoxin M partitioning between curd and whey in the preparation of cottage cheese agrees with more recent studies, but differs from previous reports. Three possible explanations for the differences are offered.     

A sensitive analytical method for six aflatoxins in rainbow trout muscle and liver

A highly sensitive analysis method for six aflatoxins (aflatoxin B?, B?, G?, G?, M? and aflatoxicol) in rainbow trout muscle and liver was developed. Aflatoxins (AFs) were extracted with acetonitrile-water (9 : 1), purified on an immunoaffinity column, and subjected to HPLC with fluorescence detection after post-column photochemical derivatization. The recoveries of AFs at 0.05 μg/kg spiking levels were 71.4-82.4% in muscle and 80.1-93.0% in liver, and the repeatability relative standard deviations (RSDr) were 0.87-4.6% in muscle and 2.0-6.2% in liver. Limits of quantitation (LOQs) and limits of detection(LODs)of AFs were estimated to be 0.004-0.029 μg/kg, and 0.002-0.012 μg/kg, respectively.     

Assessment of dietary exposure to ochratoxin A in the UK using a duplicate diet approach and analysis of urine and plasma samples

The approach to assess exposure to ochratoxin A from the diet by the analysis of human plasma and urine samples has been developed. Composite duplicate diet samples from 50 individuals and corresponding plasma and urine samples were obtained over 30 days. Samples were analysed using sensitive methods capable of measuring ochratoxin A at 0.001ng g -1 in food, 0.1ng ml -1 in plasma and 0.01ng ml -1 in urine. Analysis of the foods indicated ochratoxin A levels contributing to an average intake in the range 0.26-3.54ng kg -1 bw day -1 over the 30 days. Ochratoxin A was found in all plasma samples and in 46 urine samples. The correlation between the plasma ochratoxin A levels and ochratoxin A consumption was not significant (95% confidence limit). However, a significant correlation was found between ochratoxin A consumption and the urine ochratoxin A concentration expressed as the total amount excreted. This new work offers the possibility of using ochratoxin A in urine as a simple and reliable biomarker to estimate exposure to this mycotoxin.     

Surface binding of aflatoxin B1 by Saccharomyces cerevisiae strains with potential decontaminating abilities in indigenous fermented foods

Saccharomyces cerevisiae constitutes one of the most important microorganisms involved in food fermentations throughout the world. Aflatoxin B(1) binding abilities of S. cerevisiae strains isolated from indigenous fermented foods from Ghana, West Africa were tested in vitro. Results show that aflatoxin binding was strain specific with 7 strains binding 10-20%, 8 strains binding 20-40% and 3 strains binding more than 40% of the added aflatoxin B(1) when grown and incubated under standard conditions. Binding by two of the strains was further characterized. Highest binding capacity was seen with cells collected at the exponential growth phase with the strains A18 and 26.1.11 binding 53.0 and 48.8% of the total toxin respectively and the binding reduced towards the stationary phase. Aflatoxin B(1) binding increased steadily when the cells were incubated with 1 to 20 microg/ml of aflatoxin B(1). Binding was not affected by the cells grown at temperatures ranging from 20 to 37 degrees C, but was significantly reduced at 15 degrees C. Binding seems to be a physical phenomenon with cells treated at 52, 55 and 60 degrees C for 5 and 10 min or 120 degrees C for 20 min binding significantly higher quantities (more than 2-fold in 120 degrees C treated cells) of aflatoxin B(1) than their viable counterpart. Similarly, when the cells were treated with 2 M HCl for 1 h, up to 2-fold increase in binding was observed. The results obtained show that some strains of S. cerevisiae, viable or non-viable, are effective aflatoxin binders and these properties should be considered in the selection of starter cultures for relevant indigenous fermented foods where high aflatoxin level is a potential health risk.