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1.
From the storerooms of individual households 150 samples of dried beans and 90 samples of stored maize were collected for mycological analyses. Two of 27 isolates of A. flavus grown on malt extract agar (MEA) were found to produce the mycotoxin cyclopiazonic acid (25–36 μg/g). Three of the A. flavus isolates grown on crushed moist wheat produced aflatoxin B1 (0.72–1.6 μg/g) and 6 of 26 A. ochraceus isolates were OA positive (0.5–10.4 μg/g). None of 25 bean samples were contaminated with CPA, AF or OA, while 4 samples of 30 tested maize samples were OA positive with level of OA 0.4–400 μg/g. Toxins were determined by thin layer chromatography and colorimetric method was used for quantitations of CPA.  相似文献   

2.
High pressure liquid chromatography was used to evaluate the effects of several naturally occurring food components (selenium, vitamins A, E, B6 and C) on the in vitro metabolism of aflatoxin B1 (AFB1). AF1 was incubated with a liver microsomal enzyme metabolizing system with varying concentrations of each nutrient. The following nutrients and levels either inhibited or reduced the metabolism of AFB1: sodium selenite (25 μg/mL), d- α-tocopherol (25, 250 and 2500 μg/mL), pyridoxine hydrochloride (2.5 μg/mL), L-ascorbic acid (25 and 2500 μg/mL) and mixture containing 500 μg/mL of each chemical. Retinol acetate at levels of 2.5 and 25 μg/mL increased the level of AFB1 metabolized.  相似文献   

3.
Seventeen mold strains were isolated from ‘Greek-style’ black olives produced in Morocco. Eight of these isolates were identified as Aspergillus flavus, seven as Aspergillus petrakii, and two as Aspergillus ocharaceus Wilhelm. The A. flavus strains were tested for production of aflatoxins B1, B2, G1, and G2; and A. ochraceus and A. petrakii strains were tested for production of ochratoxin, penicillic acid, patulin, and citrinin. The organisms were tested for mycotoxin production on five different substrates, including rice powder-corn steep agar, autoclaved rice, yeast-extract sucrose broth (YES), potato dextrose agar (PDA), and fresh olive paste. All strains of A. flavus produced aflatoxins on all substrates except olive paste and PDA. In PDA, only two strains produced Aflatoxin B1. Five A. ochraceus group isolates produced penicillic acid on one or more of the substrates, but only two out of the five produced penicillic acid on olive paste. None produced ochratoxin, patulin or citrinin. Quantities of aflatoxin B1 produced in rice ranged from 5 to 14 μg/g of rice, and of penicillic acid 15–32 μg/g of rice. In olive paste, the concentrations of penicillic acid were 11.4 and 30.2 μg/g. Biological toxicity of extracts of mold cultures was confirmed using chicken embryos and a microbiological test. Crude extracts of cultures were also tested for mutagenicity using the Salmonella mutagenicity (Ames) Test, and some gave positive mutagenic responses.  相似文献   

4.
Over a period of three years 420 samples of various smoke-dried meat products, collected from individual households in different region of Croatia were analysed for the presence of aflatoxigenic strains of the Aspergillus flavus group. Strains of A. flavus and A. parasiticus were present in 17,8% of the samples, and aflatoxin-producing ability was tested in 75 strains. In relation to sequential method of aflatoxin detection, 5 of 8 isolates were found in the first step (fluorescence in aflatoxin-producing ability medium - APA) and all of them in the second step (extraction method from syntheses on moist shredded wheat - SW). A. flavus strains produced mainly aflatoxin B1, and had various levels of toxigenicity (1.4–3.12 mg/kg). Some strains of A. parasiticus produced all four aflatoxins B1 B2 G1 G2, while the other ones produced AF B1 + G1 only, with concentrations of aflatoxins from 0.1 to 450 mg/kg.  相似文献   

5.
The effect of village processing techniques on the aflatoxin content of corn and peanut products was investigated. In 30 trials, corn kernels were dehulled (bran removal), soaked for 24 h, washed and dried before grinding into flour and boiling in water to a thick consistency (Nshima). Shelled peanuts were either dry-roasted as whole kernels or ground into peanut meal and cooked. Dehulling, following by 24-h soaking (steeping) and subsequent washing significantly (P<0·05) reduced the aflatoxin B1 content of corn flour from 900 to 150 μg kg−1, and similarly that of aflatoxin G1 from 929 to 114 μg kg−1. Preparation of Nshima did not result into a substantial reduction in aflatoxin content, neither did extension of the cooking duration of 2 h afford any further decontamination. Whereas boiling peanut meal yielded a moderate reduction in the content of aflatoxins B1 and G1, roasting whole peanut kernels greatly reduced (P<0·001) the concentrations of the toxins from that in raw kernels (AFB1= 8600 μg kg−1 and AFG1=6200 μg kg−1) to 1300 and 1200 μg kg−1, respectively. These results indicate that specific processing techniques carried out in Zambian villages are effective in reducing aflatoxin carry-over into edible fractions, while others are not. © 1998 SCI.  相似文献   

6.
96 strains of Aspergillus flavus isolated from samples of stored grain and smoke-dried meat products were examined for ability to produce cyclopiazonic acid and aflatoxins, grown on mycological broth medium and malt extract agar. Five strains produced cyclopiazonic acid in the range of 0.5 — 30 mg/kg and 9 produced aflatoxin B1 (0.1 — 14.8 mg/kg) but none of them produced both cyclopiazonic acid and aflatoxins.  相似文献   

7.
In this study, we investigated the potential of aflatoxin B1 (AFB1) production by five Aspergillus flavus strains previously isolated from sorghum grains on cereals (barley, maize, rice, wheat and sorghum), oilseeds (peanuts and sesame) and pulses (greengram and horsegram). Five strains of A. flavus were inoculated on all food grains and incubated at 25 °C for 7 days; AFB1 was extracted and estimated by enzyme‐linked immunosorbent assay. All A. flavus strains produced AFB1 on all food grains ranging from 245.4 to 15 645.2 μg kg?1. Of the five strains tested, strain Af 003 produced the highest amount of AFB1 on all commodities ranging from 2245.2 to 15 645.2 μg kg?1. Comparatively, the AFB1 accumulation was high on rice grains ranging from 3125.2 to 15 645.2 μg kg?1, followed by peanuts ranging from 2206.2 to 12 466.5 μg kg?1. Less AFB1 accumulation was observed in greengram and sesame seeds ranging from 645.8 to 2245.2 and 245.4 to 2890.6 μg kg?1, respectively. Our results showed that all food grains tested are susceptible to A. flavus growth and subsequent AFB1 production.  相似文献   

8.
During mycofloral analysis of green gram (Vigna radiata (L.) R. Wilczek) seed samples taken from different grocery stores by agar and standard blotter paper methods, 5 fungal species were identified, of which Aspergillus flavus exhibited higher relative frequency (75.20% to 80.60%) and was found to produce aflatoxin B1. On screening of 11 plant essential oils against this mycotoxigenic fungi, Lippia alba essential oil was found to be most effective and showed absolute inhibition of mycelia growth at 0.28 μL/mL. The oil of L. alba was fungistatic and fungicidal at 0.14 and 0.28 μL/mL, respectively. Oil had broad range of fungitoxicity at its MIC value and was absolutely inhibited the AFB1 production level at 2.0 μL/mL. Chemical analysis of this oil revealed geranial (36.9%) and neral (29.3%) as major components followed by myrcene (18.6%). Application of a dose of 80 μL/0.25 L air of Lippia oil in the storage system significantly inhibited the fungal proliferation and aflatoxin production without affecting the seed germination rate. By the virtue of fungicidal, antiaflatoxigenic nature and potent efficacy in storage food system, L. alba oil can be commercialized as botanical fungicide for the protection of green gram seeds during storage.  相似文献   

9.
Maize (Zea mays L) germplasm is needed with resistance to infection by Aspergillus flavus and/or subsequent contamination by aflatoxin B1 (AFB1). A select group of maize populations were evaluated for their resistance to AFB1 contamination at three locations. Four populations (Ibadan B and three others derived from crosses between Corn Belt inbreds and diploid perennial teosinte. Zea diploperennis) were compared with a susceptible hybrid check in a randomised complete block experiment with 10 replicates in Georgia, Missouri and South Carolina for two years. Ears were not inoculated, and naturally occurring concentrations of AFB1 in harvested grain were analysed for population differences. Ibadan B and Mo2 W × Z diploperennis had significantly lower average amounts of AFB1, 19 μg kg?1 and 18 μg kg?1, respectively, than other test entries. Backcrossing to susceptible Corn Belt inbreds produced populations as susceptible as the check when resistance was measured as the concentrations of AFB1 in the grain. The consistency and significance of low AFB1 concentrations for Ibadan B and Mo20W × Z diploperennis suggest that these may be useful sources of resistance.  相似文献   

10.
The Aspergillus flavus population was evaluated in the period 1998–2001 in soil samples from the peanut‐growing region in Argentina. A total of 369 A flavus isolates were examined for sclerotia, aflatoxin and cyclopiazonic acid production. The L phenotype was isolated in a higher percentage than the S phenotype and represented 59% of the total isolates. Statistical analysis showed significant differences between L, S and non‐sclerotial strains with regard to aflatoxin and cyclopiazonic acid production (p < 0.05). The S strains produced higher mycotoxin levels than the L and non‐sclerotial strains. About 10% of the S strains had an unusual pattern of mycotoxin production because they simultaneously produce aflatoxins B and G and CPA. The SBG strains isolated in the present study have all morphological and microscopic characteristics of A flavus. These strains are of concern in food safety, as there is a higher probability of aflatoxin contamination in peanuts. Copyright © 2005 Society of Chemical Industry  相似文献   

11.
A new method for the simultaneous detection of 21 mycotoxins (ochratoxin A, aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, sterigmatocystin, nivalenol, deoxynivalenol, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, diacetoxyscirpenol, neosolaniol, HT-2 toxin, T-2 toxin, fumonisin B1, fumonisin B2, enniatin A, enniatin A1, enniatin B, enniatin B1, and beauvericin) in coffee beverages was internally validated. The method is based on liquid/liquid extraction with a mixture of ethyl acetate/formic acid (95:5 v/v) and detection using triple quadrupole (QqQ) and ion trap (IT) liquid chromatography tandem mass spectrometry. The limits of detection and quantification were 0.02 to 39.64 μg/kg, respectively, and the correlation coefficients were optimal for all mycotoxins (R2  0.992). The recovery values ranged from 72% to 97%. The developed method was demonstrated in six real samples of roasted and instant coffee, caffeinated and decaffeinated coffee, and coffee with sugar added. The analyses indicate the presence of the studied mycotoxins in coffee beverages at μg/kg concentrations. Ochratoxin A, a mycotoxin that is regulated in coffee, was detected in two samples under the maximum limit established by a European legislation (CE1881/2006).  相似文献   

12.
The occurrence of aflatoxin (aflatoxin B1, aflatoxin B2, aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2)) and heavy metal (Pb, Cd, As and Hg) contamination was determined in 40 industrially produced animal feed samples which were collected from the southwest of Iran. The results indicated that 75% of samples were contaminated by four aflatoxins and the level of AFB1 and sum of aflatoxins were higher than the permissible maximum levels in Iran (5 and 20 µg kg?1, respectively) in all feed samples. A positive correlation was found between four types of aflatoxins in all the tested samples (p < 0.01) and the positive correlation between AFG1 and AFG2 was significant (r2 = 0.708). All feed samples had lead concentrations lower than the maximum EU limit, while 5%, 17% and 42.5% of feed samples had As, Cd and Hg concentrations higher than the maximum limits, respectively.  相似文献   

13.
The effects of illumination, near-ultraviolet, incubation temperature pH and some minor elements on the growth rate and production of aflatoxin B1 by A. flavus and ochratoxin A by A. ochraceus were investigated. Aflatoxin B1 and ochratoxin A production was considerably higher in the light than in the dark. The greatest aflatoxin B1 and ochratoxin A production was occurred after 11 days of fermentation with light- and dark-grown cultures at 25 °C. The mycelial dry weight was also greater in the light than in the dark for both A. flavus and A. ochraceus. Exposure of conidia to near-UV irradiation increased mycelial dry weight and mycotoxins by both fungi more than white light. The greatest aflatoxin B1 and ochratoxin A was at 25 °C with UV-grown culture (24 h exposure) producing a mean of 400 and 260 μg/50 ml of medium, respectively. The maximum aflatoxin B1 and ochratoxin A yield was obtained at pH 5.5 and with increasing the initial pH to near neutrality, both mycotoxins yield decreased. Iron, cupper and zinc were observed to stimulate aflatoxin B1 and ochratoxin A production and enhanced the growth rate of both A. flavus and A. ochraceus.  相似文献   

14.
A survey of moulds and mycotoxins was performed on 99 rice samples taken from the Swedish retail market. The main objective was to study the mould and mycotoxin content in basmati rice and rice with a high content of fibre. Samples of jasmine rice as well as long-grain rice were also included. The samples were analysed for their content of ochratoxin A (high-performance liquid chromatography (HPLC)), aflatoxin B1, B2, G1, and G2 (HPLC, RIDA®QUICK), and mould (traditional cultivation methods in combination with morphological analysis). The majority of samples were sampled according to European Commission Regulation 401/2006. Subsamples were pooled and mixed before milling and both mould and mycotoxin analyses were performed on milled rice. The results showed that the majority of basmati rice (71%) and many jasmine rice samples (20%) contained detectable levels of aflatoxin B1 (level of quantification = 0.1 µg aflatoxin kg?1 rice). Two samples of jasmine rice and ten basmati rice samples contained levels over the regulated European maximum limits of 2 µg kg?1 for aflatoxin B1 or 4 µg kg?1 for total aflatoxins. Aspergillus was the most common mould genus isolated, but also Penicillium, Eurotium, Wallemia, Cladosporium, Epicoccum, Alternaria, and Trichotecium were found. The presence of Aspergillus flavus in 21% of the samples indicates that incorrect management of rice during production and storage implies a risk of mould growth and subsequent production of aflatoxin. Rough estimates showed that high rice consumers may have an intake of 2–3 ng aflatoxin kg?1 bodyweight and day?1 from rice alone. This survey shows that aflatoxin is a common contaminant in rice imported to Europe.  相似文献   

15.
The USP microbiological assay with L. leichmannii, ATCC 7830, was used to determine vitamin B12 activity in light rice miso, dark rice miso, barley miso, tempeh and tempeh burger. Unpasteurized misos were found to have the highest B12 content, averaging 0.21 μg/ 100g. Vitamin B12 activity in miso ranged from a high of 0.25 μg/ 100g in barley miso to a low of 0.15 μg/100g in light rice miso. Pasteurized tempeh contained 0.12 μg vitamin B12 per 100g food. Tempeh burger contained 0.06 to 0.11 μg vitamin B12 per 100g food. The variation in vitamin B12 activity found in these products may be due to different conditions used or produced during fermentation. Collaborative studies are needed and assessment of vitamin B12 pseudoform activity before these foods can be considered a source of vitamin B12.  相似文献   

16.
Samples of rotting sweet orange (Citrus sinensis) were obtained from the depots, sales counters and waste baskets. Fungi associated with rotting fruits were isolated and identified. Out of 12 species of fungi isolated, 8 are known to be producers of toxins. The 7 isolates of Aspergillus flavus obtained were screened for aflatoxin production in a nutrient solution, and 4 were found to be aflatoxigenic, producing primarily aflatoxin B1. Aflatoxin B1 production of the toxigenic isolates were further studied on plain juice and juice separately supplemented with 2.0% yeast extract and 2.0% sucrose. The highest yield of aflatoxin B1 was produced on juice supplemented with yeast extract by the 4 toxigenic A. flavus isolates, followed by sucrose supplementation while the lowest amount of aflatoxin B1 was detected on plain juice. Optimum temperature for aflatoxin B1 production by A. flavus isolate (IBA-O1) was 25 °C to 30 °C, for an incubation period of 7–11 days on plain and supplemented juice media.  相似文献   

17.
The extraction procedure for aflatoxin determination in maize is based on a methanol–water (8 + 2 v/v) or an acetone–water (85 + 15 v/v) mixture. Initially, the extraction efficiency of two solvents was evaluated for each aflatoxin. Different results were obtained for highly contaminated maize: significantly higher levels of aflatoxin B1 were obtained by acetone–water, on the contrary higher levels of aflatoxin G2 were achieved by methanol–water. Then, acetone–water mixtures in different proportions (7 + 3, 6 + 4 and 5 + 5 v/v) were tested to improve the extraction of aflatoxin G2. Applying these extraction mixtures, the values both of aflatoxin B1 and of other aflatoxins were generally higher compared to those obtained by acetone–water 85 + 15; moreover, acetone–water (6 + 4) and (7 + 3) showed the best extraction efficiency for all aflatoxins.  相似文献   

18.
Oral supplementation of clay to dairy cattle has been reported to reduce toxicity of aflatoxin (AF) in contaminated feed. The objective of this study was to determine the effects of 3 concentrations of dietary clay supplementation in response to an AF challenge. Ten multiparous rumen-cannulated Holstein cows [body weight (mean ± SD) = 669 ± 20 kg and 146 ± 69 d in milk], were assigned to 1 of 5 treatments in a randomized replicated 5 × 5 Latin square design balanced to measure carryover effects. Periods (21 d) were divided in an adaptation phase (d 1 to 14) and a measurement phase (d 15 to 21). From d 15 to 17, cows received an AF challenge. The challenge consisted of 100 μg of aflatoxin B1 (AFB1)/kg of dietary dry matter intake (DMI). The material was fitted into 10-mL gelatin capsules and administered into the rumen through a rumen-cannula based on the average DMI obtained on d 12 to 14. Treatments were no clay plus an AF challenge (POS); 3 different concentrations of clay (0.5, 1, or 2% of dietary DMI) plus an AF challenge; and a control consisting of no clay and no AF challenge (C). Statistical analysis was performed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Two contrasts, CONT1 (POS vs. C) and CONT2 (POS vs. the average of 0.5, 1, and 2% clay), were compared along with the linear and quadratic treatment effects (POS, 0.5%, 1%, 2%). Cows supplemented with clay had lower AF excretion in milk as aflatoxin M1 (AFM1; 0.5% = 20.83 μg/d, 1% = 22.82 μg/d, and 2% = 16.51 μg/d) and AF transfer from rumen fluid to milk (AFM1; 0.5% = 1.01%, 1% = 0.98%, and 2% = 0.74%) compared with cows in POS (AFM1 = 27.81 μg/d and AF transfer = 1.37%, CONT2). Similarly, concentrations of AFM1 in milk (0.5% = 0.35 μg/kg, 1% = 0.30 μg/kg, 2% = 0.25 μg/kg), AFB1 in feces (0.5% = 1.79 μg/g, 1% = 1.52 μg/kg, 2% = 1.48 μg/kg), and AFB1 in rumen fluid (0.5% = 0.05 μg/kg, 1% = 0.02 μg/kg, 2% = 0.02 μg/kg) were reduced in cows fed clay compared with POS (0.43 μg/kg, 2.78 μg/kg, and 0.10 μg/kg, respectively, CONT2). Cows supplemented with clay tended to have lower 3.5% fat-corrected milk [0.5% = 38.2 kg, 1% = 39.3 kg, 2% = 38.4 kg, standard error of the mean (SEM) = 1.8] than cows in POS (41.3 kg; SEM = 1.8; CONT2). Plasma superoxide dismutase (SOD) concentration tended to be lower for cows fed clay in the diet (0.5% = 2.16 U/mL, 1% = 1.90 U/mL, 2% = 2.3 U/mL; SEM = 0.3) than for cows in POS (2.72 U/mL; CONT2). Additionally, when cows were exposed to AF without clay in the diet, plasma concentrations of aspartate aminotransferase (AST) decreased from 84.23 (C) to 79.17 (POS) and glutamate dehydrogenase (GLDH) decreased from 91.02 (C) to 75.81 (POS). In conclusion, oral supplementation of clay reduced the transfer of AF from the rumen to milk and feces.  相似文献   

19.
In this study, total number of samples analysed were 20 packages of sesame and 20 cans of peanut butter, which were collected from Ankara local markets, Turkey. Extraction and determination of aflatoxins have been made by immunoaffinity column technique and high-performance liquid chromatography (HPLC) method. Mean levels (±SE) of aflatoxins B1, B2, G1 were found to be 15.756±3.129 ng/g, 1.232±0.244 ng/g and 9.689±1.005 ng/g, respectively in peanut butter samples. Regarding the sesame samples, mean level of aflatoxin G1 was found to be 0.754±0.213 ng/g. Our data revealed that while aflatoxin levels found in sesame samples were within the Turkish Food Codex (TFC) values, for peanut butter samples, they were higher than the TFC values.  相似文献   

20.
Summary Three concentrations of lactoperoxidase, 5, 50, and 500 units/ml of reaction mixture, degraded aflatoxin in the presence of 225 M NaCl and 50 M H202 at 28° C. Increasing the amount of lactoperoxidase from 50 to 500 units/ml of reaction mixture resulted in increasing the rate of degradation of aflatoxin B1 from 3.6 to 5.1%/24 h. When comparable amounts of lactoperoxidase were present, aflatoxin G1 was degraded approximately 1.5 times faster than was aflatoxin 131. At a given concentration of lactoperoxidase, aflatoxin degradation was independent of initial aflatoxin concentration. Derivatives that cochromatographed with aflatoxin B2a and derivatives that were water soluble were the major degradation products of aflatoxin B1. Similar derivatives, but in greater proportions, were noted as degradation products that resulted from activity of a blendure of mycelia ofAspergillus parasiticus.
Abbau von aflatoxin durch lactoperoxidase
Zusammenfassung Aflatoxin wurde in Gegenwart von 225 m-NaCI und 50 m-H2O2 bei 28° C durch 5, 50 bzw. 500 Einheiten von Lactoperoxidase/ml Reaktionsgemisch abgebaut. Wenn die Konzentration der Lactoperoxidase von 50 bis auf 500 Einheiten/ml Reaktionsgemisch gesteigert wurde, dann stieg die Geschwindigkeit des Aflatoxinabbaues von 3,6 bis auf 5,1%/24 Std. Lactoperoxidase baute Aflatoxin G1 1,5 mal schneller ab als Aflatoxin B1. Die Konzentration des Aflatoxins zu Beginn spielte keine Rolle beim Abbau durch, die Lactoperoxidase. Die Abbauprodukte von Aflatoxin B 1 waren chromatografisch dem Aflatoxin B2a ähnlich oder waren wasserlöslich. Gleiche Abbauprodukte, aber in größeren Anteilen, erhielt man durch das Mycel vonAspergillus parasiticus.
  相似文献   

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