GREEN METHODS FOR AFLATOXIN B1 DEGRADATION IN MAIZE

Aflatoxin B1 (AFB1) is the most harmful mycotoxin, primarily produced by Aspergillus flavus and A. parasiticus and can contaminate a wide range of cereal grains, including maize. Several methods have been explored for removing this mycotoxin from cereals. Due to its remarkable chemical stability, oxidative processes have proven effective in degrading AFB1, particularly those that generate free radicals. These processes include physical (e.g. plasma), chemical (e.g. ozone) and biological (e.g. oxidoreductive enzymes) methods. The aim of this study was to evaluate the effectiveness of two alternative decontamination methods, cold plasma and Ery4 laccase enzyme in contaminated maize. Cold plasma: a stream of plasma-treated gas generated by Dielectric Barrier Discharge (DBD) was introduced into a container with contaminated samples artificially contaminated maize (AFB1, 50 μg/kg). The study investigated the effects of cold plasma using O2-fed (air liquid, 99.999%) and N2 synthetic air (air liquid, 99.999%) plasma. Both gas showed break down effectively AFB1 in vitro: O2-fed plasma (77 ± 11%) and N2 synthetic air plasma (79 ± 5%) analysed by HPLC/FLD. The study revealed that the degradation of AFB1 in maize increased with treatment time (20 min > 3 min), suggesting that longer exposure allows for a higher concentration of reactive species such as free radicals, which are considered the primary agents of degradation. Furthermore, this study demonstrated that O2-fed plasma was more effective (23 ± 3 %) than N2 used as a gas feed (15 ± 4 %), indicating that reactive oxygen species are more efficient than reactive nitrogen ones in degrading AFB1 [1]. Ery4 laccase: the recombinant Ery4 laccase (5 U/mL) was tested in combination with acetosyringone (AS) (10 mM) as a mediator on artificially contaminated maize (50 μg/kg) after 3h of treatment. While complete degradation was achieved in vitro under the same experimental conditions, the AFB1 degradation in maize reached 26 ± 8% [2]. The presence of AFB1 degradation products was investigated by LC/HRMS in both methods. We identified several AFB1 degradation products through accurate mass measurements, showing cleavage and hydroxylation of the furan ring. Although further studies are needed to minimize matrix effects and evaluate the technological impact of these decontamination methods, the results of this study are promising and indicate that AFB1 can be reduced on agricultural commodities such as maize. These methods avoid the use of harmful chemicals and high temperatures with a focus on sustainability.