Avaliação da aflatoxina em sementes de amendoim armazenadas e do óleo de nim (Azadirachta indica) no crescimento micelial do fungo Aspergillus flavus.

Abstract

The aflatoxin is a toxin commonly found in peanuts, produced by mycotoxigenic fungi, where appear mainly Aspergillus flavus and Aspergillus parasiticus. The attack of these fungi may cause different alterations in seeds and grains, being the most important the decrease in the germinative power in seeds, the alterations in the natural color of the grains, in the organoleptical qualities, in the nutrition facts and in the industrial uses of peanuts and its by products, besides of producing toxic substances. The search for low-cost products that can control these micro-organisms with efficiency has been constant, but many effects are observed when these fungi are exposed to products made from neem (Azadirachta indica), such as the morphological and toxicogenic alterations. Having in mind the problems caused by these micro-organisms, the present work aimed the determination of the storage conditions, kind of packages and storage periods, aiming to reduce significantly the aflatoxin rate in peanut seeds and evaluate the action of neem oil (Azadirachta indica), in the mycelial development of the Aspergillus flavus fungus. To reach the objectives, two experiments were installed. The frist one with entirely casual delineation with four repetitions, followed by a factorial scheme of 2 x 2 x 2 x 4, represented by storage enviroments (A1 – dried chamber; A2 – enviromental conditions), package (EM1 – multi-ply bag; EM2 – woven polyethylene bag), processing (AM1 – peanut without peel; AM2 – peanut with peel) and storage period (P1 – after 45 days; P2 – after 90 days; P3 – after 135 days; P4 – after 180 days). The second experiment was distributed in factorial scheme of 3x5 represented by: different isolated of Aspergillus flavus fungus (IM – isolated of Mogeiro; IP – isolated of Patos; ICG – isolated of Campina Grande) and variation of the neem oil concentrations in the culture medium (C0 – testimony; C1 – 3,125 %; C2 – 6,25 %; C3 – 12,5 %; C4 – 25 %) with four repetitions. From the results found, we concluded that the enviroment conditions, packages, processing and storage period have influenced in the phisiological qualitiy of the seed and have not favored the aflatoxin appearance; and the concentration of 25 % of neem oil inhibited significantly the mycelial growth rate of the Aspergillus flavus fungus.