OZONE TREATMENT AS A POSSIBLE STRATEGY FOR REDUCTION OF MYCOTOXINS, PESTICIDES AND MICROBIAL CONTAMINATION IN DURUM WHEAT

Deoxynivalenol (DON) occurs frequently in wheat grains and it is often associated with significant levels of its modified form DON-3-glucoside (DON-3G). Several approaches were tested in the past to prevent the formation of DON in the field or reduce its level in the grains. Ozone (O3) is a powerful disinfectant and oxidant that reacts quite easily with specific compounds including mycotoxins and pesticides. It was demonstrated to degrade these contaminants in aqueous solution and it has the potential to be also effective for decontamination of grains. Ozone in gaseous form as a fumigant gave also promising results against insects and a wide range of microorganisms including bacteria, fungi, viruses, protozoa and fungi spores that may grow and survive on wheat during storage. Moreover, it is classified as GRAS (Generally Recognised As Safe) which makes very attractive its use in food industry. However, ozone is unstable and decays naturally into inactive diatomic oxygen (O2) and it must be continuously added in the mass of the grain to maintain the active concentrations. We have tested the efficacy of gaseous ozone treatments for reduction of mycotoxins, pesticides, heavy metals, bacteria, fungi and yeasts in durum wheat grain naturally contaminated with low levels of these contaminants. A prototype was tested to continuously and homogeneously dispense ozone in 2 kg aliquots of durum wheat. Levels and distribution of contaminants were measured before and after ozone treatments (different concentrations and time of exposure), as well as in all fractions obtained during wheat processing. The optimal conditions of ozone treatments were identified in order to maximize the reduction of contaminants and maintain unaffected chemical and rheological parameters of durum wheat. Therefore, optimal ozonation conditions were applied to 20 kg of durum wheat that were successively processed into semolina and pasta. A significant reduction of the levels of some contaminants was obtained, with minor influence on qualitative parameters of durum wheat. The scale up at industrial level for ozone treatment of wheat grains will be discussed.