Assessing Purdue Improved Crop Storage (PICS) bags to mitigate fungal growth and aflatoxin contamination

Storing maize in regions of the world without sufficient drying and storage capacity is challenging due to the potential risk of aflatoxin contamination produced by Aspergillus flavus. This study sought to determine if storage of maize in Purdue Improved Crop Storage (PICS) bags prevents mold growth and aflatoxin accumulation. PICS bags are a three-layer, hermitic bag-system that forms a barrier against the influx of oxygen and the escape of carbon dioxide. Maize conditioned at 12, 15, 18, and 21% grain moisture was inoculated with 50 g of maize kernels infected with fluorescent-marked strain of A. flavus. The grain was stored in either PICS or woven bags at 26 °C, and percent oxygen/carbon dioxide levels, fungal growth, aflatoxin, moisture content, and kernel germination were assessed after 1 and 2 months incubation. Maize stored in woven bags was found to equilibrate with the ambient moisture environment over both storage periods, while PICS bags retained their original moisture levels. Aspergillus flavus growth and aflatoxin accumulation were not observed in maize stored in any PICS bags. No aflatoxin B1 was detected in woven bags containing low-moisture maize (12 and 15%), but detectable levels of aflatoxin were observed in high moisture maize (18 and 21%). The percentage of oxygen and carbon dioxide within PICS bags were dependent on initial grain moisture. Higher carbon dioxide levels were observed in the bags stored for 1 month than for 2 months. High initial moisture and carbon dioxide levels correlated with low kernel germination, with the 18 and 21% treatment groups having no seeds germinate. The results of the study demonstrate that storage of maize in PICS bags is a viable management tool for preventing aflatoxin accumulation in storage.     

Mycoflora and aflatoxin contamination in shelled pistachio nuts

A total of 143 pistachio nut samples collected during harvest, storage and processing were examined for mould growth and aflatoxin production. The mould count was in the range of 10³?10⁴ cfu g^?1 and 10⁵?10⁶ cfu g^?1 for the harvest and storage samples, respectively. The growth of Aspergillus flavus was 38-5-39-5% on the surface of the shells and 6–16% on the kernels without aflatoxin production. The contamination level of A flavus varied among samples collected from different regions. Peeling off the soft shell of pistachio nuts by hand reduced the contamination risk of A flavus to kernels. The predominant flora on stored pistachio nuts were Aspergillus, Penicillium, Cladosporium, Rhizopus, while the genera of Ulocladium, Trichothecium, Aureobasidium and Eurotium were less frequent. Thirty-five percent of the A flavus isolates produced aflatoxins on synthetic media.     

Spread of Aspergillus flavus and aflatoxin accumulation in postharvested maize treated with biocontrol products

Maize is a major staple crop and calorie source for many people living in Sub-Saharan Africa. In this region, Aspergillus flavus causes ear rot in maize, contributing to food insecurity due to aflatoxin contamination. The biological control principle of competitive exclusion has been applied in both the United States and Africa to reduce aflatoxin levels in maize grain at harvest by introducing atoxigenic strains that out-compete toxigenic strains. The goal of this study was to determine if the efficacy of preharvest biocontrol treatments carry over into the postharvest drying period, the time between harvest and the point when grain moisture is safe for storage. In Sub-Sahara Africa, this period often is extended by weather and the complexities of postharvest drying practices. Maize grain was collected from fields in Texas and North Carolina that were treated with commercial biocontrol products and untreated control fields. To simulate moisture conditions similar to those experienced by farmers during drying in Sub-Sahara Africa, we adjusted the grain to 20% moisture content and incubated it at 28 °C for 6 days. Although the initial number of kernels infected by fungal species was high in most samples, less than 24% of kernels were infected with Aspergillus flavus and aflatoxin levels were low (<4 ppb). Both toxigenic and atoxigenic strains grew and spread through the grain over the incubation period, and aflatoxin levels increased, even in samples from biocontrol-treated fields. Our molecular analysis suggests that applied biocontrol strains from treated fields may have migrated to untreated fields. These results also indicate that the population of toxigenic A. flavus in the harvested grain will increase and produce aflatoxin during the drying period when moisture is high. Therefore, we conclude that preharvest biocontrol applications will not replace the need for better postharvest practices that reduce the drying time between harvest and storage.     

Aspergillus flavus infection and aflatoxin production in mixtures of high-moisture and dry maize

High-moisture (26·6–27·9% m.c.) and dry (9·8% m.c.) fractions of white and yellow maize were examined for fungal development and aflatoxin production during an 8-week incubation at 25°C. Treatment procedures included blending of either high-moisture white with dry yellow or high-moisture yellow with dry white maize fractions (average moisture in blend, 14%) and inoculation of some test maizes with A. flavus spores. At sampling time white and yellow components of maize blends were manually separated and all of the maize samples were analyzed for levels of moisture, fungal infection and aflatoxin. Moisture levels in maize blends equilibrated rapidly during the initial 2–4 days of incubation; neither dry yellow nor dry white exceeded 13% moisture during the trial period. Only a limited incidence of A. flavus was observed on uninoculated maize. but in samples treated with A. flavus spores a high infection rate developed; from 58 to 98% of the kernels in dry fractions of inoculated blends were infected with A. flavus during the trial. Aflatoxin was detected in high-moisture maize and in both high-moisture and dry fractions of inoculated maize blends. Up to 500 μg aflatoxin B₁/kg of corn was found after the 8-week incubation in a dry fraction of inoculated maize blends.     

Fungal contamination and aflatoxin content of maize,moringa and peanut foods from rural subsistence farms in South Haiti

Mycotoxins are toxic, low molecular weight compounds produced by fungi. Among them, aflatoxins are the most carcinogenic and they mainly impact on rural communities of developing countries. The present study supplies data on mycobiota and aflatoxin contamination in the most common food products consumed in Haiti. The study concerns analyses performed on 49 samples of meals and seeds collected in South Haiti and tested for fungal occurrence and aflatoxin content by HPLC-DAD technique. The results revealed that three main fungal genera affected Haitian food products: Aspergillus spp. (Section Flavi and Nigri), followed by Penicillium spp. and Fusarium spp. Aflatoxin was present in more than half of the samples of maize (Zea mays L.) kernels (55%), maize meal (57%) and moringa (Moringa oleifera Lam.) seeds (64%), and in 25% of peanut (Arachis hypogaea L.) samples. The tested food products were mostly contaminated by aflatoxin B₁ (AFB₁) followed by aflatoxin B₂ (AFB₂), while no aflatoxins type G were detected. The total concentration of aflatoxins in the positive samples was 228 μg/kg on average, i.e., fifty-seven and eleven times higher than the maximum levels allowed in Europe and USA, respectively. Both the presence of aflatoxigenic fungi and aflatoxin contamination in maize kernels seemed to be related to agricultural practices, such as weed control, irrigation and growing cycle length. These findings suggest that the Haitian population is strongly exposed to aflatoxin risk. This risk could be reduced by exploiting simple and accessible farming strategies for minimizing mycotoxin contamination, at least for maize.     

Mould infection and aflatoxin contamination of the peanut kernels harvested from spring and fall crops as affected by artificial inoculation of the seeded kernels with Aspergillus flavus and Aspergillus niger

Spring and fall crops of peanut are grown each year in Taiwan. Mould infection and aflatoxin contamination of crops as affected by artificial inoculation of the seeded kernels with conidia of Aspergillus flavus, A niger and a combination of A flavus and A niger (inocula > 10⁵ CFU kernel⁻¹) were determined. Three cultivars, ie Tainan 9, Tainan 11 and Tainan 12, were consecutively grown for fall 1996, spring 1997, fall 1997 and spring 1998 crops with green vegetable pea for rotation. In crops from uninoculated kernels (control), percentages of germination and harvested plants were higher in spring crops than in fall crops. Inoculation with A niger alone or with A flavus resulted in various levels of seed and seedling mortality and lower yields of peanut pods than yields of the other inoculation treatments. When harvested and sized (US No 1), kernels were subjected to examination for mould colonisation and analysis of aflatoxin content. Fairly low percentages were colonised and aflatoxin contents were low or non-detectable. Colonisation and aflatoxin content were independent of artificial inoculation. Average aflatoxin contents in the kernels harvested from all cultivars and crops ranged from 0 to 6.1 µg kg⁻¹. However, the highest levels of aflatoxin content among samples of the four crops were 4.0, 18.2, 9.6 and 36.7 µg kg⁻¹, respectively. © 1999 Society of Chemical Industry     

Delivery systems for biological control agents to manage aflatoxin contamination of pre-harvest maize

While soil application of a competitive non-toxigenic Aspergillus flavus strains is successful in reducing aflatoxin contamination in certain crops, direct application to aerial reproductive structures could be more effective for maize. A sprayable, clay-based water-dispersible granule formulation was developed to deliver non-toxigenic A. flavus strain K49 directly to maize ears. The efficacy of the K49 water-dispersible granule in mitigating aflatoxin in maize (Zea mays L.) was evaluated. Field studies were conducted to compare K49 colonization and effectiveness in reducing aflatoxin contamination when applied either as a soil inoculant or as a directed spray in plots infested with toxigenic strain F3W4. Fifty percent of non-toxigenic A. flavus was recovered from non-treated controls and from plots soil inoculated with K49 on wheat. In spray treatments with formulated or unformulated K49 conidia, over 90% of A. flavus recovered was non-toxigenic. Soil-applied K49 reduced aflatoxin contamination by 65% and spray applications reduced contamination by 97%. These findings suggest direct spray application of non-toxigenic A. flavus strains may be better than soil inoculation at controlling maize aflatoxin contamination and that a water-dispersible granule is a viable delivery system for maintaining viability and efficacy of the biological control agent, K49.     

Detection of Aspergillus spp. and aflatoxin B1 in rice in India

Twelve hundred rice samples consisting of paddy (675) and milled rice (525) were collected from 20 states across India. These samples were assessed for Aspergillus spp. infection on selective medium and aflatoxin B₁ (AFB1) by indirect competitive ELISA. In this investigation, Aspergillus flavus contamination dominated in all the seed samples. The other major contaminants were Aspergillus niger, Aspergillus ochraceus and Aspergillus parasiticus. Out of 1200 rice samples, 67.8% showed AFB1 ranging from 0.1 to 308.0 μg/kg. All the paddy samples from Chattishgarh, Meghalaya and Tamil Nadu showed AFB1 contamination. Milled rice grains from different states showed below the permissible levels of AFB1 (average 0.5–3.5 μg/kg). Eighty-two percent of samples from open storage that were exposed to rain showed AFB1 contamination followed by one-year-old seed. Out of 1200 samples, 2% showed AFB1 contamination above the permissible limits (>30 μg/kg). This is the first comprehensive report of aflatoxin contamination in rice across 20 states in India.     

Fungi and aflatoxin in a bin of stored white maize

Samples of maize from discolored spots in the surface layer of stored grain in a southeast Missouri bin were examined for variation in microbial profile and for the presence of aflatoxin. Comparisons were made with samples of non-discolored maize from the same bin. Deteriorated test kernels showed a high incidence of Penicillium, Absidia, Mucor, Rhizopus and Fusarium spp., as well as bacteria and yeasts. Aspergillus species were also frequently observed; A. flavus was the most common species in this group. In one sample of discolored maize 80 per cent of the kernels contained A. flavus and the sample had 0·40 ppm aflatoxin B₁. Other fractions exhibited extensive discoloration but no aflatoxin.     

Correlation and classification of single kernel fluorescence hyperspectral data with aflatoxin concentration in corn kernels inoculated with Aspergillus flavus spores

The objective of this study was to examine the relationship between fluorescence emissions of corn kernels inoculated with Aspergillus flavus and aflatoxin contamination levels within the kernels. Aflatoxin contamination in corn has been a long-standing problem plaguing the grain industry with potentially devastating consequences to corn growers. In this study, aflatoxin-contaminated corn kernels were produced through artificial inoculation of corn ears in the field with toxigenic A. flavus spores. The kernel fluorescence emission data were taken with a fluorescence hyperspectral imaging system when corn kernels were excited with ultraviolet light. Raw fluorescence image data were preprocessed and regions of interest in each image were created for all kernels. The regions of interest were used to extract spectral signatures and statistical information. The aflatoxin contamination level of single corn kernels was then chemically measured using affinity column chromatography. A fluorescence peak shift phenomenon was noted among different groups of kernels with different aflatoxin contamination levels. The fluorescence peak shift was found to move more toward the longer wavelength in the blue region for the highly contaminated kernels and toward the shorter wavelengths for the clean kernels. Highly contaminated kernels were also found to have a lower fluorescence peak magnitude compared with the less contaminated kernels. It was also noted that a general negative correlation exists between measured aflatoxin and the fluorescence image bands in the blue and green regions. The correlation coefficients of determination, r ², was 0.72 for the multiple linear regression model. The multivariate analysis of variance found that the fluorescence means of four aflatoxin groups, <1, 1–20, 20–100, and ≥100 ng g^?1 (parts per billion), were significantly different from each other at the 0.01 level of alpha. Classification accuracy under a two-class schema ranged from 0.84 to 0.91 when a threshold of either 20 or 100 ng g^?1 was used. Overall, the results indicate that fluorescence hyperspectral imaging may be applicable in estimating aflatoxin content in individual corn kernels.     

Natural infection of cowpea (Vigna unguiculata (L.) Walp.) by toxigenic fungi and mycotoxin contamination in Benin, West Africa

Natural infection of cowpea by toxigenic fungi and mycotoxin contamination in Benin, West Africa were studied. Cowpea samples were collected at harvest (T₀) and after three months of storage (T₃) from the four agro-ecological zones of the country. A total of 92 representative samples were analysed for the two periods. About 23 fungal species were identified on cowpea seed samples across zones of which Aspergillus flavus, a fungus that produces aflatoxins, was most frequently encountered. Fusarium species shown to produce fumonisins were not recorded from cowpea seeds. Overall incidence of A. flavus infection was found to increase after storage from 7.6% at T₀ to 28.25% at T₃. In spite of this natural infection of cowpea, very low levels of fumonisin and aflatoxin were detected. Only three out of the 92 cowpea samples, all collected at T₀, were found to be fumonisin B₁ positive with a mean level of 0.03 μg/g. Similarly, only six samples out of the 92, all collected at T₃, were aflatoxin B₁ positive with mean levels of 3.58 μg/kg. Fumonisin (B₂ and B₃) and aflatoxin (B₂, G₁ and G₂) were not detected in any of the samples. Contrary to the situation with maize and groundnut where high levels of toxin are often detected in naturally infected samples, the current results indicate that cowpea is less susceptible to mycotoxin contamination. A low susceptibility could be due to the presence in cowpea of substances that inhibit mycotoxin biosynthesis. Further investigations are underway to confirm this hypothesis.     

Co-occurrence of fumonisins with aflatoxins in home-stored maize for human consumption in rural villages of Tanzania

This study determined maize-user practices that influence the presence of fumonisin and aflatoxin contamination of maize in food consumed in the rural areas of Tanzania. Samples of the 2005 maize harvest in Tanzania were collected from 120 households and examined for fumonisins and aflatoxins. Information on whether the maize was sorted to remove defective (visibly damaged or mouldy) maize before storage and whether the damaged and mouldy maize or the non-dehulled maize was used as food was also collected. In addition, the percentage of defective kernels in the samples was determined. Ninety per cent of the households sorted out defective maize, 45% consumed the defective maize and 30% consumed non-dehulled maize. In 52% of the samples fumonisins were determined at levels up to 11,048 µg kg^?1 (median = 363 µg kg^?1) and in 15% exceeded 1000 µg kg^?1; the maximum tolerable limit (MTL) for fumonisins in maize for human consumption in other countries. Aflatoxins were detected in 18% of the samples at levels up to 158 µg kg^?1 (median = 24 µg kg^?1). Twelve per cent of the samples exceeded the Tanzanian limit for total aflatoxins (10 µg kg^?1). Aflatoxins co-occurred with fumonisins in 10% of the samples. The percentage defective kernels (mean = 22%) correlated positively (r = 0.39) with the fumonisin levels. Tanzanians are at a risk of exposure to fumonisins and aflatoxins in maize. There is a need for further research on fumonisin and aflatoxin exposure in Tanzania to develop appropriate control strategies.     

A survey on distribution and toxigenicity of Aspergillus section Flavi in poultry feeds

Thirty-five samples of poultry feeds and corresponding raw materials (maize, soybean and meat meal) from a processing plant were analyzed to evaluate the distribution and toxigenicity of Aspergillus section Flavi isolates. Mycological analysis of the samples indicated the presence of five fungal genera (Aspergillus, Penicillium, Fusarium, Cladosporium, and Eurotium). Aspergillus flavus was the predominant species being present in 48.5% of the analyzed samples. Ninety-one isolates belonging to Aspergillus section Flavi were isolated; ninety were identified as A. flavus and only one as A. parasiticus. Fifty-seven isolates were capable of producing sclerotia, 41 were identified as L-type strains and 16 as type S. Fifty-seven percent of the isolates produced AFB₁ levels ranging from 0.05 μg/kg to 27.7 μg/kg whereas 86.8% produced CPA from 1.5 μg/kg to 137.8 μg/kg. L-strains produced from 0.05 to 14.8 μg/kg of aflatoxin and type S produced levels from 0.05 to 1.65 μg/kg. No significant differences in CPA production among S- and L-strains were observed. Sclerotial isolates produced AFB₁ levels ranging between 0.05 and 27.7 μg/kg and CPA levels from 3.8 to 47.3 μg/kg. More than half of the A. flavus isolates were able to produce AFB and CPA simultaneously. Twenty percent of the 35 samples were contaminated with aflatoxin B₁ whereas 34.3% were contaminated with CPA. The high rate of CPA producing isolates represents a potential risk of contamination with this toxin in poultry feeds.     

Aflatoxin and Cyclopiazonic Acid Production by Aspergillus flavus Isolated from Contaminated Maize

Seven truck-loads of maize were tested for mycotoxin contamination. Aflatoxin was identified in all 7 at concentrations from 3 ng/g-501 ng/g (aflatoxin B₁+ B₂). Cyclopiazonic acid was identified in 4 loads with concentrations from 25-250 ng/g. Deoxynivalenol was found in 4 of 5 loads tested, over a range of 46-676 ng/g. Ninteeen isolates of Aspergillus flavus from the samples were tested for ability to accumulate cyclopiazonic acid and aflatoxin in liquid culture. Fourteen produced cyclopiazonic acid (0.5-135 μg/mL), 12 produced aflatoxin (0.01-0.70 μg/mL, aflatoxin B₁+ B₂), and one aflatoxin-producing isolate did not produce cyclopiazonic acid.     

Household dietary exposure to aflatoxins from maize and maize products in Kenya

Aflatoxicosis has repeatedly affected Kenyans, particularly in the eastern region, due to consumption of contaminated maize. However, save for the cases of acute toxicity, the levels of sub-lethal exposure have not been adequately assessed. It is believed that this type of exposure does exist even during the seasons when acute toxicity does not occur. This study, therefore, was designed to assess the exposure of households to aflatoxins through consumption of maize and maize products. Twenty samples each of maize kernels, muthokoi and maize meal were randomly sampled from households in Kibwezi District of Makueni County in Eastern Kenya and analysed for aflatoxin contamination. The samples were quantitatively analysed for aflatoxin contamination using HPLC. The uncertainty and variability in dietary exposure was quantitatively modelled in Ms Excel using Monte Carlo simulation in @Risk software. Aflatoxins were found in 45% of maize kernels at between 18 and 480 μg kg^–1, 20% of muthokoi at between 12 and 123 μg kg^–1, and 35% of maize meal at between 6 and 30 μg kg^–1. The mean dietary exposure to aflatoxin in maize kernels was 292 ± 1567 ng kg^?1 body weight day^?1, while the mean dietary exposure to aflatoxin in maize meal and muthokoi were 59 ± 62 and 27 ± 154 ng kg^?1 body weight day^?1 respectively. The results showed that the amount and frequency of consumption of the three foods is the more important contributing factor than the mean aflatoxin concentration levels, to the risk of dietary exposure to aflatoxins.     

The fate of aflatoxins during the production of “Ogiri”, a West African fermented melon seed condiment from artificially contaminated seeds

Twenty-six market samples and four laboratory-prepared samples of “ogiri” were screened for aflatoxin contamination. Aflatoxins were not detected in any of the samples. The fermented product (ogiri) was prepared with Aspergillus flavus contaminated melon seeds. Losses of 64.7% aflatoxin B₁ and 82.9% aflatoxin G₁ were observed at the end of the third day of fermentation of the ground melon seeds. The samples were completely detoxified at the fourth day of fermentation. Increase in pH of the mash from 6.2 to 7.2 was observed during fermentation.     

INFLUENCE OF OTHER FUNGI ON AFLATOXIN PRODUCTION BY ASPERGILLUS FLAVUS IN MAIZE KERNELS

Experiments were designed to determine whether certain nontoxigenic fungi commonly isolated from maize kernels can affect aflatoxin B₁ development when inoculated with A. flavus onto individual unsterilized, and autoclaved maize kernels . Trichoderma viride and Aspergillus niger were found to be strongly antagonist inhibiting the growth of A. flavus by 87 and 66% respectively, whereas Aspergillus versicolor, Fusarium moniliforme, Paecilomyces variotii and Emericella quadrillineata inhibited the growth of A. flavus by less than 51%. Less aflatoxin B₁ was detected when A. flavus was paired with A. niger or T. viride than with the other test fungi. When A. niger or T. viride was introduced onto the kernels 72 h before inoculation with A. flavus, no aflatoxin B₁ was detected in unsterilized kernels and the levels of aflatoxin B₁ were greatly reduced from 700 ppb to 160 and 140 ppb in autoclaved kernels, respectively. When inoculation of A. flavus followed 72 h of incubation of either A. niger and T. viride, no aflatoxin B₁ was detected. However, when both A. niger and T. viride were introduced 72 h after inoculation with A. flavus, the levels of aflatoxin B₁ were reduced to 385 and 560 ppb, respectively in unsterilized and autoclaved maize kernels . Trichoderma viride and Aspergillus niger may be useful in biological control of aflatoxin contamination of maize kernels .; Accepted for Publication June 11, 1997     

Influence of the cropping pattern on aflatoxin contamination in preharvest Kharif (monsoon) maize crop (Zea mays)

Aflatoxin contamination in three varieties of maize (Zea mays L), viz Diara composite, M₉ and Suwan composite, under various cultivation rates and planting densities was examined during the 1987 and 1989 Kharif (monsoon) crops. Cultivation rates comprising single line weeding (SLW) with one spading, SLW with two spadings and SLW with three spadings did not have significant effects on aflatoxin production in the preharvest standing crop. Of the three planting populations, the toxin level was highest under 56000 plants ha^?1 followed by 83000 plants ha^?1, and 67000 plants ha^?1 in Aspergillus flavus inoculated plots (I₁) and uninoculated plots (I₀), respectively. The variety M₉ was most susceptible to A flavus infection and supported higher aflatoxin production under I₁ condition. Aflatoxin concentration was lowest in Diara composite. Correlation analysis showed a positive and highly significant relation between A flavus incidence and aflatoxin contamination (r = +0.73, P < 0.01).     

Influence of storage environment on maize grain: CO2 production,dry matter losses and aflatoxins contamination

Poor storage of cereals, such as maize can lead to both nutritional losses and mycotoxin contamination. The aim of this study was to examine the respiration of maize either naturally contaminated or inoculated with Aspergillus flavus to examine whether this might be an early and sensitive indicator of aflatoxin (AF) contamination and relative storability risk. We thus examined the relationship between different interacting storage environmental conditions (0.80–0.99 water activity (a_w) and 15–35°C) in naturally contaminated and irradiated maize grain + A. flavus on relative respiration rates (R), dry matter losses (DMLs) and aflatoxin B1 and B2 (AFB1-B2) contamination. Temporal respiration and total CO₂ production were analysed by GC-TCD, and results used to calculate the DMLs due to colonisation. AFs contamination was quantified at the end of the storage period by HPLC MS/MS. The highest respiration rates occurred at 0.95 a_w and 30–35°C representing between 0.5% and 18% DMLs. Optimum AFs contamination was at the same a_w at 30°C. Highest AFs contamination occurred in maize colonised only by A. flavus. A significant positive correlation between % DMLs and AFB1 contamination was obtained (r = 0.866, p < 0.001) in the irradiated maize treatments inoculated with A. flavus. In naturally contaminated maize + A. flavus inoculum loss of only 0.56% DML resulted in AFB1 contamination levels exceeding the EU legislative limits for food. This suggests that there is a very low threshold tolerance during storage of maize to minimise AFB1 contamination. This data can be used to develop models that can be effectively used in enhancing management for storage of maize to minimise risks of mycotoxin contamination.     

Effect of synthetic antioxidants on stored maize grain mycoflora in situ

BACKGROUND: The influence of a mixture of butylated hydroxyanisole (BHA) and propyl paraben (PP) (each at a concentration of 20 mmol L^?1) on mycoflora and Aspergillus section Flavi populations in stored maize grain was evaluated. A survey of 120 maize samples was carried out from June to November 2005. RESULTS: The predominant populations in non‐treated (control) maize between the first and sixth sampling periods were Aspergillus section Flavi and Penicillium. Aspergillus flavus was the fungus most frequently isolated from both control and antioxidant‐treated kernels. All samples of control and antioxidant‐treated maize kernels were negative for aflatoxins during the 6 month storage period. Aspergillus flavus and A. parasiticus strains showed a variable ability to produce aflatoxins. The contribution of the strains to silo community toxigenicity was higher for A. flavus L (large) and S (small) strains in the fourth sampling period. CONCLUSION: Antioxidant treatment negatively affected natural maize mycoflora and Aspergillus section Flavi populations between the second and sixth months of storage. Copyright © 2007 Society of Chemical Industry