Ozone treatment for aflatoxin reduction in soybean

Improper handling of soybeans (Glycine max L.) can lead to contamination by aflatoxins produced by Aspergillus flavus (A. flavus). This study investigated the ozonation technique in decontaminating aflatoxin, as well as the physical and microbiological quality of soybeans. Soybeans were contaminated with A. flavus and placed in an incubator for 20 days at 30°C with a relative humidity of 95% to stimulate aflatoxin production. Ozone exposure was conducted using the corona discharge technique at 125 volts and 10 ppm for 30 and 60 minutes. Exposure to ozone for 60 minutes efficiently eliminated 97% of AFB1, 96% of AFB2, and 97% of total AFB. The population of A. flavus decreased from 5.2 Log CFU/g to 3.2 Log CFU/g. Additionally, ozonation reduced the initial and inoculated soybean’s water activity (aw) values from 0.72 to 0.67 and 0.89 to 0.87, respectively. The study demonstrated that A. flavus underwent morphological damage, characterized by conidia’s destruction and conidiophores’ shrinking. Furthermore, ozonation suppressed the morphological growth of A. flavus in both treatment conditions. The study revealed that ozonation successfully eliminates aflatoxins, decreases the presence of A. flavus, reduces aw values, and hinders the growth and alters the morphology of A. flavus on soybean, as evidenced by the suboptimal development of sterigmata and conidia.