Resumo

Fungi are often found on the field and during food storage, when exposed to optimal environment conditions such as high temperature and humidity, and some species can produce mycotoxins in food. Strategies of chemical decontamination in food, as ozone O₃ gas application, may have several advantages, as it decomposes rapidly to molecular oxygen without leaving residues and is considered as Generally recognized as safe-GRAS for use in food processing. The aim of this work was to explore the (a) in vitro-antifungal effects of O₃ gas on different fungi strains: Fusarium graminearum, Fusarium verticillioides, Penicillium citrinum, Aspergillus parasiticus and Aspergillus flavus, regarding colony growth/conidia germination/hyphae alterations (morphology, mortality and reactive oxygen species (ROS) production) by applying light, scanning electron and fluorescence microscopy. Moreover, the effects of O₃ gas were evaluated on (b) in vivo-wheat grains for F.graminearum and deoxynivalenol (DON) decontamination. Wheat grains were artificially contaminated (spiked) with F.graminearum (1x10⁴ spores/mL) in silos pilots (25x10 cm height/diameter) of storage for O₃ gas exposition. The fungi colonies total count were performed after the treatments. On the other hand, the DON artificially contamination were performed (Control: 4238 mg/kg) for to evaluate the degradation with O₃ gas exposition in the same silos. The DON extraction were performed with immunoaffinity column for LC/UV (liquid chromatography/ultraviolet) method. O₃ gas were obtained (40 and 60 µmol/mol) at different times of exposure (15,30,60,120 and 180 min - test carried out dependent).O₃ gas efficiently inhibited the fungi colonies growth, especially F.graminearum (Treated: no growth; Control: 38 mm) and P.citrinum species (Treated: no growth; Control: 23 mm). At the concentration applied of 60 µmol/mol for 120 min, O₃ gas exposure was able to inhibit conidia germination, especially F.graminearum (Treated: 3%; Control: 99% of germination), caused hyphae morphological alterations and led to hyphae death and ROS production in all fungi genera/species tested. Its action can be related to cell metabolism alterations, leading to apoptosis and oxidative stress, which can contribute to fungi growth inhibition. In wheat grains artificially contaminated, the concentration of 60 µmol/mol for 180 min of exposure was able to efficiently inhibit total growth of F.graminearum spores. Moreover, that concentration exposure for 60 min was efficient to DON total degradation. Data suggest that O₃ gas application can be further studied as an effective fungicide on agriculture (storage) and food safety (packaging or raw materials treatment).