Aflatoxins In Peanuts Research Articles

Determination of aflatoxins in peanuts by matrix solid-phase dispersion and liquid chromatography

A new method based on matrix solid-phase dispersion (MSPD) extraction was studied to determine aflatoxin B1, B2, G1 and G2 from peanuts. Optimization of different parameters, such as type of solid supports for matrix dispersion and elution solvents were carried out. The method used 2 g of peanut sample, 2 g of C 18 bonded silica as MSPD sorbent and acetonitrile as eluting solvent. Recoveries of each aflatoxin spiked to peanut samples at 2.5 ng/g (5 ng/g for aflatoxin G2) level were between 78 and 86% with relative standard deviations ranging from 4 to 7%. The limits of quantification ranged from 0.125 to 2.5 ng/g for the four studied aflatoxins using liquid chromatography (LC) with fluorescence detection. In addition, LC coupled to mass spectrometry with an electrospray interface was used for confirmation of aflatoxins present in real samples. Eleven peanut samples from different countries were analyzed by the proposed method and by using an enzyme-linked immunosorbent assay (ELISA). ELISA test is a good screening method for investigation of these mycotoxins in peanut samples.

Biocontrol of aflatoxins in peanuts

Aflatoxins remain the most important mycotoxin problem in the world, and peanuts are a major source of these toxins. Control of aflatoxin levels in peanuts on a commercial scale is possible by colour sorting and aflatoxin assays on shelled peanuts, and this is widely practised in developed countries. However, this procedure is expensive.

Sampling plan for the analysis of aflatoxin in peanuts and corn: an update

Sampling plan for the analysis of aflatoxin in peanuts and corn: an update

Simultaneous Quantitation of Aspergillus flavus/A. parasiticus and Aflatoxins in Peanuts

A method was developed for simultaneous quantitation of Aspergillus flavus/A. parasiticus and aflatoxins in peanuts. Peanut samples were ground with an equal weight of water in a vertical cutter mixer to produce a slurry. Separate subsamples were taken for dilution-plating to determine total colony forming units (CFU)/g of A. flavus/A. parasiticus and for liquid chromatographic analysis to determine aflatoxin concentrations. Dry-grinding peanuts for homogenization of aflatoxins produced high temperatures that killed most of the A. flavus/A. parasiticus propagules. Addition of water to produce a slurry kept the temperature from rising above levels that killed the fungi. A 7 min grind time provided optimal homogenization for both the fungi and aflatoxins, so long as the temperature of the slurry did not exceed 45 degrees C. In the analysis of 60 shelled peanut samples, total aflatoxin concentrations ranged from 0 to 10,000 ng/g and total A. flavus/A. parasiticus ranged from 1.4 x 10(3) to 3.2 x 10(6) CFU/g. Regression analysis showed a significant positive correlation (p < 0.0001) between the quantities of A. flavus/A. parasiticus and aflatoxin (R2 = 0.82).

Sampling plan for the analysis of aflatoxin in peanuts and corn: an update

The aim of this paper was to update the sampling plan for analysis of mycotoxins in grains, formerly published by the author. The proposed alterations were based on the acquired experience on its application and on FAO recommendations. This update restricts the scope of the former plan and establishes a sampling plan for analysis of aflatoxin in peanuts and corn, by means of modified formulas, the minimum number of sacks or points (when in bulk) from which incremental samples should be drawn to make a bulk sample. Fractional exponents (square roots) of the formulas proportionally decrease the number of sacks/points to be sampled as the lot size increases. Operating Characteristic (OC) curves developed for in-shell and shelled peanuts and corn as well as trend curves of the coefficient variation for different sample sizes (weights) are presented.

Sampling wheat for deoxynivalenol.

The variability associated with testing wheat for deoxynivalenol (DON) was measured using a 0.454 kg sample, a Romer mill, 25 g of comminuted subsample and the Romer Fluoroquant analytical method. The total variability was partitioned into sampling, sample preparation, and analytical variability components. Each variance component was found to be a function of the DON concentration and equations were developed to predict each variance component using regression techniques. The effects of sample size, subsample size, and number of aliquots on reducing the variability of the DON test procedure were also determined. Using the test procedure described above, the coefficient of variation (CV) associated with testing wheat at 5 ppm DON was found to be 13.4%. The CVs associated with sampling, sample preparation, and analysis were 6.3, 10.0, and 6.3%, respectively. The sample variations associated with testing wheat are relatively small when compared to CVs associated with testing other commodities for other mycotoxins such as aflatoxin in peanuts. Even with the use of a small sample size (0.454 kg), the sampling variation was not the largest source of error as found in other mycotoxin test procedures.

Conidial movement of nontoxigenic Aspergillus flavus and A. parasiticus in peanut fields following application to soil.

The use of nontoxigenic strains of Aspergillus flavus and A. parasiticus in biological control effectively reduces aflatoxin in peanuts when conidium- producing inoculum is applied to the soil surface. In this study, the movement of conidia in soil was examined following natural rainfall and controlled precipitation from a sprinkler irrigation system. Conidia of nontoxigenic A. flavus and A. parasiticus remained near the soil surface despite repeated rainfall and varying amounts of applied water from irrigation. In addition, rainfall washed the conidia along the peanut furrows for up to 100 meters downstream from the experimental plot boundary. The dispersal gradient was otherwise very steep upstream along the furrows and in directions perpendicular to the peanut rows. The retention of biocontrol conidia in the upper soil layers is likely important in reducing aflatoxin contamination of peanuts and aerial crops such as corn and cottonseed.

Sampling, Sample Preparation, and Analytical Variability Associated with Testing Wheat for Deoxynivalenol

The variability associated with testing wheat for deoxynivalenol (DON) was measured using a 0.454 kg sample, Romer mill, 25 g comminuted subsample, and the Romer Fluoroquant analytical method. The total variability was partitioned into sampling, sample preparation, and analytical variability components. Each variance component was a function of the DON concentration and equations were developed to predict each variance component using regression techniques. The effect of sample size, subsample size, and number of aliquots on reducing the variability of the DON test procedure was also determined. For the test procedure, the coefficient of variation (CV) associated with testing wheat at 5 ppm was 13.4%. The CVs associated with sampling, sample preparation, and analysis were 6.3, 10.0, and 6.3%, respectively. For the sample variation, a 0.454 kg sample was used; for the sample preparation variation, a Romer mill and a 25 g subsample were used; for the analytical variation, the Romer Fluoroquant method was used. The CVs associated with testing wheat are relatively small compared to the CV associated with testing other commodities for other mycotoxins, such as aflatoxin in peanuts. Even when the small sample size of 0.454 kg was used, the sampling variation was not the largest source of error as found in other mycotoxin test procedures.

Occurrence of aflatoxins in peanuts and peanut products consumed in the State of São Paulo/Brazil from 1995 to 1997

One hundred and thirty seven samples of peanuts and peanut containing foods were collected in markets in the State of São Paulo, Brazil, between January 1995 an December 1997. Most of the samples were collected by the Inspection Service of São Paulo Secretary of Health. The foods included raw peanuts, peanut candies ("paçoca" and "pé de moleque"), peanut butter, fried/roasted salted peanuts, "torrone", chocolate coated peanuts and salt-coated peanuts. The samples were analyzed for aflatoxins using a thin-layer chromatographic method. About 45% of the samples were positive for aflatoxins and 27% exceeded the limits of the Brazilian legislation (30.0 µg.kg-1 for aflatoxins B1+G1). The aflatoxins were confirmed by derivatization with trifluoroacetic acid. The 90th percentile was 110.0 in 1995, 60.0 in 1996 and 118.0 µg.kg-1 in 1997. The aflatoxins concentration in the raw peanut samples ranged from 5.0 to 382.0 µg.kg-1 and 27.1% were above the legal limits. Contamination in peanut candies was above the limit in 32.8% of the samples and the aflatoxins levels ranged from 6.0 to 494.0 µg.kg-1. Contamination of salty peanuts was less frequent, around 10% of the samples and the toxin levels were usually below 10 µg.kg-1. The maximum level of contamination, 536.0 µg.kg-1, was found in a sample of peanut with a salty coat ("amendoim japonês"). Results of previous studies in peanuts and peanut products in the city of São Paulo from 1980-1987 had 68.75% of the samples with levels greater than the limit 30.0 µg.kg-1 and the 90th percentile ranged from 42.0 to 333.0 µg.kg-1. In 1994, 36.0% of the samples showed results above the limit and the 90th percentile was 489 µg.kg-1. The results show that aflatoxins contamination in peanuts is decreasing but it is still a serious problem in Brazil, a country where the climate, the agricultural practices and storage conditions favour fungal growth.

Investigations of the Problems of Assessing Aflatoxin Levels in Peanuts

In this study, a number of probability distributions that have been used to model the occurrence of aflatoxin in peanuts are compared. Two distributions, the compound gamma and the negative binomial, are shown to have special appeal in that both can be justified by reasoning from the fundamental biological and stochastic processes that generate the aflatoxin. Since method of moments and maximum likelihood give consistent estimates of parameters in both models, practical considerations suggest using the former. One hundred twenty data sets, each consisting of fifty observations, were not sufficient to provide goodness-of-fit tests to establish either as superior to the other as a model. Both models fit the data well, appreciably better than other models examined. An attractive aspect of the compound gamma and the negative binomial distributions is that, as a consequence of their theoretical underpinnings, both involve parameters that have meaningful interpretations. In the compound gamma, the alpha parameter reflects the shape of the kernel-to-kernel aflatoxin content distribution, the lambda parameter reflects the number (or frequency) of contaminated kernels in the sample, and the beta parameter is a scale parameter. In the negative binomial, the two parameters can be used as measures of mean or location and shape.

Comparison of Three Methods for Determining Aflatoxins in Melon Seeds

The suitability of 3 methods for determining aflatoxins in melon seeds was examined. The first 2 are the Contaminants Branch (CB) method and the Best Foods (BF) method, both official methods for determining aflatoxins in peanuts and peanut products. The third method, the modified CB method-Rapid Modification of the Cottonseed (CB-RCS-Mod) method, devised in this work, was derived by combining steps from the CB method and the Rapid Modification of the Cottonseed method. The CB method was superior to the other 2 methods for quantitation of aflatoxins. It gave better recoveries and cleaner extracts that exhibit less fluorescent interference for thin-layer chromatography (TLC) than the BF method. Also, its solvent efficiency was better than that of the CB-RCS-Mod method. With the CB method, recoveries from spiked samples were 85.0% for aflatoxin B1 and 90.0% for aflatoxin B2. Recoveries of G aflatoxins were more variable, averaging 90.0% for aflatoxin G1 and 72.5% for aflatoxin G2. Total aflatoxin recovery was 86.5% for the CB method. At a low aflatoxin contamination level (8 micrograms B1/kg sample), aflatoxin B1 was detectable by the CB method but not by the BF method. Detection of aflatoxins in BF method sample extracts by TLC was not improved by the use of chloroform-acetone-water (88 + 12 + 1), benzene-ethanol-water, or ether-methanol-water (96 + 3 + 1) in place of the standard chloroform-acetone (88 + 12) developer. Use of ether-methanol-water (96 + 3 + 1) for detecting aflatoxins by TLC in the CB method extracts increased interference compared with the standard chloroform-acetone (88 + 12) developer.

A Note on High Moisture Content Foreign Material Effects on Aflatoxin in Peanuts During Storage

Abstract Samples containing four types of high moisture content foreign material were placed in warehouses to determine how this material may contribute to aflatoxin formation in peanuts during storage. The high moisture material included gherkins, maypops, briarballs, and citrons. Results showed aflatoxin levels exceeding 700 ppb in some shelled peanut samples. Frequency tests showed 9% of all grade samples from farmers stock lots contained high moisture foreign material. When averaged across an entire warehouse, the high moisture foreign material could raise the average aflatoxin level in storage by 30 ppb.

Rapid Screening Method for Resistance to Aflatoxin Production in Peanut1

Abstract A simple, economical, and rapid method to detect aflatoxin in peanut is described in this paper. The extract from 1 g of peanut is added to 1 mL of NH4H2PO4-HgCl2 solution containing 0.005 g agar in a tube. The concentration of aflatoxin can be visually estimated by the tube fluorescence which is directly correlated with the concentration of aflatoxin on a simple linear regression (r = 0.999, P &amp;lt; 0.01). The lowest aflatoxin amount that could be detected was 0.02 μg/g by a spectroflurophotometer and was 0.04 μg/g by visual observation under UV light. There was no significant difference between the amounts of aflatoxin estimated by the tube fluorescence method and by TLC (P &amp;gt; 0.10) in an experiment containing 10 samples. This method should be applicable for fast identification of peanut genotypes of single plants with resistance to aflatoxin production.

The Use of HPLC/Thermospray Ms for the Confirmation of Aflatoxins in Peanuts

Abstract An HPLC/Thermospray MS method is described for the determination of aflatoxins B1, B2, G1 and G2 in peanut extracts. Samples are extracted and prepared for analysis using an SPE method. The final determination utilizes reversed phase HPLC with a thermospray MS detector. The use of the MS allowed for unequivocal identification of aflatoxins in the extracts.

Preharvest aflatoxin in peanuts

Preharvest aflatoxin in peanuts

Inexpensive, rapid screening method for aflatoxins in peanuts and peanut products

AbstractSurveys of major Brazilian foodstuffs demonstrated that peanuts and peanut products continue to be very susceptible to aflatoxin contamination. To prevent, or at least minimise, the problem the aflatoxins need to be monitored by a rapid and inexpensive screening method. The AOAC Romer method has been used and found highly reliable. However, the clean‐up step utilises anhydrous FeCl3 and basic CuCO3 which are expensive and not readily available in Brazil. Thus, the extraction (with a mixture of 270 ml methanol plus 30ml 40 g litre−1 aqueous KCl) and clean‐up (150 ml 100 g litre−1 aqueous CuSO4) steps of the method of Soares and Rodriguez‐Amaya (1985) were combined with the AOAC minicolumn to provide a rapid, inexpensive screening technique. Fifty‐two sample lots of peanuts and peanut products were screened by this and Romer's method, and the results were in complete agreement: 28 samples were negative, four &lt; 20 μg kg−1, 12 in the range 20–50 μg kg−1, three in the range 50–100 μg kg−1 and 5 &gt;100 μg kg−1. The results also agreed well when the extracts obtained by the two methods were submitted to quantitative TLC.

The occurrence of aflatoxins in peanuts imported into Czechoslovakia for human consumption.

Results of 492 analyses for aflatoxin in raw shelled peanuts imported into Czechoslovakia during 1982-1984 are presented. Most samples (55.3%) had aflatoxin content less than the detection limit of the radioimmunochemical screening method (0.8 micrograms/kg). Further analyses showed that 239 out of 410 samples of roasted peanuts contained aflatoxin below the detection limit. Only 1.9% of all peanut samples were found to have contamination level more than 5 micrograms/kg aflatoxin. The highest levels of aflatoxin observed were in a raw peanut sample containing 202.1 micrograms/kg and in a roasted peanut sample containing 32.6 micrograms/kg.

Cost-effectiveness of lowering the aflatoxin tolerance level

The cost-effectiveness of adopting aflatoxin tolerance levels of 15, 10 and 5 ppb for peanuts and peanut products was assessed. Estimates of the annual cost to manufacturers of monitoring and controlling peanut aflatoxin levels at the current 20-ppb action level, and estimates of the projected increase in costs of establishing lower tolerances were elicited from producers by questionnaire. Exposures to peanut products were derived from the HANES 1 survey and from peanut production statistics. The risk of liver cancer at each tolerance level was estimated using both epidemiological and extrapolated experimental data assuming that exposure would be reduced in direct proportion to the decrease in the tolerance. It was found that the 15-ppb tolerance would cost $60,000 per cancer death averted (range $20,000–$1,700,000) and is therefore relatively cost-effective. The marginal costs per life saved for both the 10-ppb and 5-ppb levels were found to be $1.7 million (range $0.6 million–$11.4 million) and $1.6 million (range $0.6 million–$31.1 million), respectively. Conclusions on the optimal regulatory approach should be guided by comparisons of these figures with corresponding cost-effectiveness ratios for alternative regulatory uses of national resources in the interests of public health.

The Destruction of Aflatoxins in Peanuts by Microwave Roasting

The effectiveness of microwave roasting for reducing aflatoxin contamination in peanuts was investigated. Contaminated peanuts were treated in a specially constructed experimental microwave unit in 2kg batches for various times at two different power levels. The results suggest that aflatoxin contamination can be consistently reduced by better than 95% by heating the nuts to a temperature of at least 150°C. The rate of heating appears to have very little or no effect since similar results were obtained for a 5min treatment at a power level of 3.2kW and a 16min treatment at 1.6kW. These treatments also resulted in a satisfactory degree of browning, while protein and fatty acid content were not measurably affected. The operating cost of a microwave processor is estimated to be 1.5¢/kg.

Carcinogens occurring naturally in food.

Carcinogens naturally occurring in food include metabolites of microorganisms which infect plants during harvesting and storage; products of the normal metabolism of plants and products of chemical changes occurring during processing, preservation, preparation or which are picked up from the environment, including contaminated water or soil. Some examples of these types of carcinogens are: fungal metabolites such as aflatoxins in peanuts stored under improper conditions; safrol from the oil of various plants; tannin in tea, grain and grapes; and polycyclic hydrocarbons including benzo (a) pyrene formed by smoking meat and fish. Epidemiological studies indicate that there is a high incidence of gastric cancer in the areas of the world where smoked fish are common in diets. Vitamin A may play a role in preventing the carcinogenic action of polycyclic hydrocarbons.