Revista Brasileira de Milho e Sorgo (Aug 2005)
CHEMICAL AND BIOLOGICAL PROTECTION OF HUMID CORN GRAINS AGAINST STORAGE FUNGI AND AFLATOXINS PRODUCTION
Abstract
Grains of corn cultivars HD 9486 with 19,7% moisture were treated, immediately after harvest, with solutions of Eucalyptus citriodora extract (40%), Eucalyptus citriodora essence (20%), acetic acid (5%), uréia (5%), sodium acetate (5%); benomyl (25g a.i. 100kg-1 of grains), thiabendazole (45g) and fludioxonil (3g), sunflower oil, mineral oil and suspension of 106 CFU.ml-1 of Sacharomyces cerevisiae. To the check grains ,water was added obeying the same relationship used in other treatments (0.75% grain weight /product volume). Those grains were stored in a continuous aeration system, constituted of 200 liter metallic drums with steel screen bottoms on ducts of aeration; and in a non-aeration system, constituted of metal bottom drums on wood bases. The experimental design was entirely randomized with 24 treatments (plots with 80 kg of grains) in 3 replications. The efficiency in the control of Aspergillus flavus and Penicillium spp. was evaluated being quantified the percentage of grains visually moldy after 17 days of storage. In the non-aeration system, the fungicides benomyl, thiabendazole and fludioxonil controlled those fungi at levels below the tolerance limit, that is, 3% , while the check presented 49.6% of moldy grains . The moisture averages and the temperature between grains were 15.5% and 35.5 oC, respectively. In the aerated system all treatments presented low level of moldy grains (1.2% in the check), suggesting that in that storage period the temperature and grains moisture were unfavorable to the development of those fungi. At the time, aflatoxins levels (μg.kg-1) were evaluated, being used the ELISA and the thin layer chromatographic methods. In the aerated condition, the corn grains presented the smallest aflatoxins levels and were significantly different (P <0,05) when compared with values found in non-aerated condition. In aerated condition, the largest efficiency in the protection of the corn grains in relation to the aflatoxins biosynthesis (2.1 μg.kg-1 of B1 + B2 + G1+G2) was verified in the treatment with thiabendazole. It is concluded that the continuous aeration and the grains protection with benomyl, thiabendazole and fludioxonil are efficient against the grain moldy caused by Aspergillus flavus and Penicillium spp. and in the reduction of the aflatoxins biosynthesis.
