Inactivation of Bacillus cereus Spores on Red Chili Peppers Using a Combined Treatment of Aqueous Chlorine Dioxide and Hot-Air Drying

The effect of a combined treatment using aqueous chlorine dioxide (ClO₂) and hot-air drying to inactivate Bacillus cereus spores on red chili peppers was evaluated. Ten washed and dried pepper samples, each comprising half of a single pepper (Capsicum annuum L.), were inoculated with B. cereus spore suspension. The inoculated samples were washed with sodium hypochlorite (NaOCl; 50, 100, or 200 μg/mL) or ClO₂ (50, 100, or 200 μg/mL) solution for 1 min and then air-dried (25 ± 1 °C, 47 ± 1% relative humidity), which was followed by drying with hot air at 55 °C for up to 48 h. The spore populations on the samples were enumerated and their a_w and chromaticity values were measured. The spore numbers immediately after treatment with NaOCl and ClO₂ were not significantly different. A more rapid reduction in spore numbers was observed in the samples treated with ClO₂ than those treated with NaOCl during drying. A combined treatment of ClO₂ and hot-air drying significantly reduced the spore populations to below the detection limit (1.7 log CFU/sample). B. cereus spores on chili peppers were successfully inactivated by washing with ClO₂ solution followed by hot-air drying whereas the pepper color was maintained.