Physicochemical treatments for the reduction of aflatoxins and Aspergillus niger in corn grains (Zea mays)

BACKGROUND Corn grains are commonly contaminated with mycotoxins and fungi. The purpose of this study was to evaluate the reduction of aflatoxins B-1, B-2, G(1), and G(2) and the inhibition of Aspergillus niger in corn grains using ultrasound, ultraviolet (UV) radiation, electrolyzed water, and sodium bicarbonate. The determination of aflatoxins was performed by high-performance liquid chromatography with fluorescence detection and postcolumn derivatization, and analysis of A. niger was performed by evaluating mycelial growth in potato dextrose agar. The best treatment for reducing aflatoxins and inhibiting mycelial growth was evaluated in corn contaminated with A. niger. RESULTS The results show a significant reduction in aflatoxins in the following order: sodium bicarbonate > ultrasound > UV > electrolyzed water for aflatoxins B-1, B-2, and G(2). For aflatoxin G(1), the order of reduction was sodium bicarbonate > ultrasound > electrolyzed water > UV, with maximum values between 70.50% and 87.03% reached with sodium bicarbonate; for the other treatments, the reduction was between 51.51% and 65.44%. Regarding the fungus, the order of inhibition in the control of mycelial growth was sodium bicarbonate > ultrasound > electrolyzed water > UV in corn grains, and inhibition of mycelial growth was obtained at a sodium bicarbonate concentration of 3.0 g L-1. CONCLUSION Sodium bicarbonate, electrolyzed water, ultrasound, and UV radiation inhibited the growth of A. niger on potato dextrose agar and reduced the contents of aflatoxins B-1, B-2, G(1), and G(2) in vitro. Sodium bicarbonate showed an ability to inhibit mycelial growth in corn grains. (c) 2020 Society of Chemical Industry

Automated summary

In this study, ultrasound, UV radiation, electrolyzed water, and sodium bicarbonate were used to treat corn grains contaminated with aflatoxins and Aspergillus niger. The results showed that sodium bicarbonate was the most effective in reducing aflatoxins and inhibiting mycelial growth of A. niger.