ABSTRACT
BACKGROUND: Corn grains are commonly contaminated with mycotoxins and fungi. The purpose of this study was to evaluate the reduction of aflatoxins B1 , B2 , G1 , and G2 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 B1 , B2 , and G2 . For aflatoxin G1 , 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 B1 , B2 , G1 , and G2 in vitro. Sodium bicarbonate showed an ability to inhibit mycelial growth in corn grains. © 2020 Society of Chemical Industry.
Subject(s)
Aflatoxins/chemistry , Aspergillus niger/metabolism , Food Preservation/methods , Zea mays/chemistry , Zea mays/microbiology , Aflatoxins/metabolism , Aspergillus niger/drug effects , Aspergillus niger/radiation effects , Food Preservation/instrumentation , Seeds/chemistry , Seeds/microbiology , Sodium Bicarbonate/pharmacology , Ultrasonics , Ultraviolet RaysABSTRACT
This work focuses on the disinfection actual urban wastewater by the combination of ultrasound (US) irradiation and electrodisinfection with Dimensionally Stable Anodes (DSA). First, the inactivation of Escherichia coli (E. coli) during the sonochemical disinfection was studied at increasing ultrasound power. Results showed that it was not possible to achieve a complete disinfection, even at the highest US power (200 W) dosed by the experimental device used. Next, the electrodisinfection with DSA anodes at different current densities was studied, finding that it was necessary a minimum current density of 11.46 A m(-2) to reach the complete disinfection. Finally, an integrated sonoelectrodisinfection process was studied. Results showed a synergistic effect when coupling US irradiation with DSA electrodisinfection, with a synergy coefficient higher than 200% of the disinfection rate attained for the highest US power applied. In this process, hypochlorite and chloramines were identified as the main reagents for the disinfection process (neither chlorate nor perchlorate were detected), and the presence of trihalomethanes was far below acceptable values. Confirming this synergistic effect with DSA anodes opens the door to novel efficient disinfection processes, limiting the occurrence of hazardous disinfection by-products.
