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

Wiley Online Library


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 aw 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.

Practical Application

Chili peppers may be treated with sodium hypochlorite (NaOCl) or aqueous chlorine dioxide (ClO2) in combination with hot-air drying to remove Bacillus cereus spores. While NaOCl or ClO2 alone may remove some spores, combined treatment with ClO2 and hot-air drying is more effective in terms of reducing spore numbers. The color of chili samples was not affected by the combined treatment of ClO2 and hot-air drying.

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