|CHAI, HUI-ERH - National Taiwan University|
|Hwang, Cheng An|
|SHEEN, LEE-YAN - National Taiwan University|
Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2021
Publication Date: 9/14/2021
Citation: Chai, H., Hwang, C., Huang, L., Wu, V.C., Sheen, L. 2021. Efficacy of gaseous chlorine dioxide for decontamination of Salmonella, Shiga toxin-producing Escherichia coli, and Listeria monocytogenes on almonds and peppercorns. Food Control. https://doi.org/10.1016/j.foodcont.2021.108556.
Interpretive Summary: Almonds and peppercorns have been implicated in outbreaks of foodborne illnesses caused by bacterial pathogens (Salmonella, pathogenic Escherichia coli, and Listeria monocytogenes). This study evaluated the use of gaseous chlorine dioxide (ClO2) for decontamination of bacterial pathogens on raw almonds and black peppercorns. Results showed that the increase of cumulative ClO2 expousre from 983 to10,408 and to 8,039 ppm-h, respectively, increased the reductions of pathogens on almonds and peppercorns. The cumulative ClO2 exposures to achieve a 4.0-log reduction of the pathogens on almonds and peppercorns were10,408 and 3,112 ppm-h, respectively. The ClO2 treatment method could be used in pilot-scale or larger decontamin ation application for almonds and peppercorns.
Technical Abstract: Almonds and peppercorns have been implicated in outbreaks of foodborne illnesses caused by bacterial pathogens. The objective of this study was to evaluate the efficacy of gaseous chlorine dioxide (ClO2) for pilot-scale decontamination of bacterial pathogens on raw almonds and black peppercorns. Almonds and peppercorns were inoculated by dipping in cell suspensions of Salmonella, Shiga toxin-producing Escherichia coli (STEC), or Listeria monocytogenes and then drying overnight at room temperature to achieve an inoculum level of 6-7 log CFU/g. The samples were treated by exposure to ClO2 gas generated by mixing two ClO2-generating dry powders of NaClO2 and FeCl3 for 5 h or intermittently controlled dosing of HCl solutions to NaClO2 powder for 15 h at 20±2°C and 70±5% RH. The concentrations of ClO2 (ppm) during the treatment duration (h) were recorded to obtain the cumulative ClO2 exposure (ppm-h). The populations of the pathogens on almonds and peppercorns before and after ClO2 treatment were enumerated to determine the inactivation caused by the cumulative ClO2 exposure. Results showed that increasing the cumulative exposure from 983 to 10,408 ppm-h increased the reduction of Salmonella, STEC, and L. monocytogenes from 1.1 to 4.1, 1.6 to 4.1, and 1.4 to 4.1 log CFU/g, respectively, on almonds. For peppercorns, increasing the cumulative exposure from 983 to 8,039 ppm-h led to increased reductions of Salmonella, STEC, and L. monocytogenes from 3.0 to 6.0, 3.7 to 7.2, and 3.2 to 7.3 log CFU/g, respectively. Gaseous ClO2 decontamination treatment was more effective for peppercorns than almonds. A 4.0-log reduction of the pathogens would need an exposure of 10,408 ppm-h for almonds and 3,112 ppm-h for peppercorns. However, ClO2 exposures =3,700 ppm-h for almonds and =4,175 ppm-h for peppercorns would bleach the color of the treated samples. Treatment parameters obtained from this study could be used in pilot-scale or larger decontamination applications for almonds and peppercorns.