The influence of gaseous ozone and ozonated water on microbial flora and degradation of aflatoxin B1 in dried figs

Abstract

In this study, the effectiveness of gaseous ozone and ozonated water on microbial flora and aflatoxin B1 content of dried figs were investigated. After dried figs were exposed to13.8 mg L−1 ozone gas and 1.7 mg L−1 ozonated water for 7.5, 15 and 30 min, variation of aerobic mesophilic bacteria (AMB), E. coli, coliform, yeast and mold counts were determined. Before and after ozone treatments molds on dried figs were also isolated and identified. In both ozone treatments, AMB was not exactly inactivated whereas E. coli was completely destroyed at 7.5 min. Coliform, and yeast were also destroyed at 7.5 and 15 min in ozonated water, respectively. Ozone applications at 15 min were sufficient for inactivation of all molds. Aspergillus flavus and Aspergillus parasiticus which cause aflatoxin formation were isolated from dried figs. Artificially contaminated with aflatoxin B1 samples were also treated with gaseous ozone and ozonated water for 30, 60 and 180 min, respectively. In both of treatments, degradation of aflatoxin B1 was increased due to increasing of ozonation time. Results indicated that gaseous ozone was more effective than ozonated water for reduction of aflatoxin B1, whereas ozonated water was affected for decreasing microbial counts.