Antimicrobial activity of gaseous chlorine dioxide against Aspergillus flavus on green coffee beans

Abstract

The aim of this study was to use chlorine dioxide (ClO2) gas to inactivate Aspergillus flavus on green coffee beans. Green coffee beans inoculated with A. flavus were exposed to ClO2 gas generated from 0.75, 1, 1.25, or 1.5 mL of ClO2 solution in a sealed container at 25 or 50 degrees C (100% relative humidity [RH]) for up to 10 h. Numbers of A. flavus on beans treated at 25 degrees C decreased by 1.1-2.2 log cfu/bean within 1 h of exposure to ClO2 and decreased to below the detection limit (<= 1.0 log cfu/bean) at all ClO2 concentrations after 10 h. At 50 degrees C, the microbial population reached the detection limit within 0.5 h regardless of the ClO2 solution concentration. Beans exposed to gas for 10 h at 25 degrees C were stored for 14 days under conditions of 43, 75, or 100% RH and 4, 12, or 25 degrees C. At 4 degrees C, visible mold growth was not established regardless of RH. After 12 days, mold was observed only at 25 degrees C. At 100% RH, beans stored under the same conditions without ClO2 gas treatment showed mold formation at 13 and 4 days at 12 and 25 degrees C, respectively.