The effect of storage on mycoflora profile was monitored bimonthly in 36 corn (Zea mays L.) samples, dividing the same sample into groups dried to 11 and 14% moisture content (1008 analysis). These groups were further subdivided based on the initial total count (moulds and yeasts) up to 10(4) CFU g(-1) (12 samples, range 1.6 x 10(4) to 9.0 x 10(4), mean 3.8 x 10(4) CFU g(-1)) and up to 10(5) CFU g(-1) (24 samples, range 1.0 x 10(5) to 5.0 x 10(5), mean 2.7 x 10(5) CFU g(-1)). In the corn group dried to 11%, the fumonisin content was analysed at the initial stage (freshly harvested) and at the end of 12-month storage. Fusarium spp. and Penicillium spp. prevailed at the freshly harvested stage (100%), maintaining this profile throughout 12 months, in corn dried to both 11 and 14%. Cladosporium spp., Aspergillus spp. and Phoma spp. were also detected at lower frequencies during the storage. Fusarium spp. and the total fungal colony count during 12-month storage carried out with samples dried to 11 or 14% moisture content were statistically evaluated using ANOVA for randomized complete block design. The correlation between storage time and Fusarium spp. and total fungal colony count data was analysed by Pearson's correlation test. There was no difference in Fusarium spp. and total counts in the 10(4) CFU g(-1) initial total count group throughout the storage time (p < 0.05). There was a negative correlation between fungal population and storage time (p < 0.05) in the 10(5) CFU g(-1) initial total count group. Fumonisins were detected in all freshly harvested corn, at a mean concentration of 9.9 +/- 6.0 micro g g(-1) (range 0.74-22.6 micro g g(-)1). These values did not change in the 12-month stored corn (mean of 9.9 +/- 5.8 micro g g(-1), range 0.81-23.7 micro g g(-1)). These post harvest data indicated the importance of moisture content at the crop harvesting/predrying stage to control fungal growth and further fumonisin production.

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Zearalenone (ZEA) adsorption by a mixture of organic (yeast cell wall) and inorganic (activated charcoal) adsorbents was evaluated by an incomplete Box Behnken (33) statistical design with a quintuplicate at the central point. The variables analysed were different ratios of adsorbents (yeast cell wall and activated charcoal) at 100:0, 87.5:12.5 and 75:25, pH (3.0, 4.5 and 6.0) and ZEA concentrations (300, 750 and 1,200 ng/ml). The adsorbent mixture at 75:25 showed higher efficiency for ZEA adsorption (≯96.1%) than the 87.5:12.5 ratio (81.3 to 93.7%) and with the pure yeast cell wall (78.1 to 55.7%). The significant variables were the ratio of adsorbent mixture and ZEA concentration. The effect of pH was not significant (P=0.05), indicating that the binding between ZEA and the adsorbent would be stable at different pH (3.0, 4.5 and 6.0). The quadratic model obtained by the Box Behnken (33) design can be used for predictive purposes, because it showed a non-significant deviation (P=49.54%) and a good correlation coefficient (R2=0.98), suggesting that the ZEA adsorption would be maximum (100%) when the adsorbent mixture is set at 75:25 and the ZEA concentration at 300 ng/ml. Although the predictive model showed that an increase in adsorption efficiency could occur in a smaller ZEA concentration (300 ng/ml), the mixture at the 75:25 ratio presented high efficiency (≯98%) in adsorption when high ZEA concentrations were used (1,200 ng/ml), indicating that these mixtures would be able to adsorb a wide range of ZEA concentrations. Therefore, this mixture of yeast cell wall and activated charcoal adsorbents at 75:25 might be a candidate for further in vivo testing.

The natural co-occurrence of fumonisins and aflatoxins was investigated in freshly harvested corn kernels (150 samples, 62 hybrids), acquired from the Central-Southern (27 samples, 21 hybrids), Central-Western (86 samples, 51 hybrids) and Northern (37 samples, 18 hybrids) regions of the State of Paraná, Brazil using enzyme-linked immunosorbent assay (ELISA). Fumonisins were detected in 147 (98%) samples at a concentration range of 0.096 to 22.6 microg/g, while aflatoxins were detected in 17 (11.3%). All the aflatoxin-positive samples (range 38.0-460.0 ng/g) came from the Central-Western region and were co-contaminated with fumonisins. Fumonisin contamination was higher in corn from the Northern (9.85 microg/g) and Central-Western regions (5.08 microg/g), when compared with the Central-Southern region (1.14 microg/g). The overall evaluation detected 62% samples with fumonisin levels < or = 5.0 microg/g. Regional differences affected fumonisin levels in the same hybrid, regardless of Fusarium count and moisture content, suggesting interference from climatic conditions, in addition to the local predominance of toxigenic strains of the Fusarium biotype.