Purpose: This study determined the effectiveness of a slow-releasing ClO2 gas generated from self-contained sachets to reduce Salmonella contamination on spices and to see if this treatment would be applicable on a small-scale. The combined effect of ClO2 gas treatment and storage time on Salmonella levels on spices was evaluated.
Methods: Three different spices (black peppercorns, sesame seeds, and cumin seeds) were inoculated with a cocktail of five different nalidixic acid resistant Salmonella strains by soaking and mixing the spices in the cocktail for 30 min. The inoculated spices were then dried in a biosafety hood for 24 h. Spices were treated with 0, 100, 200, or 500 mg ClO2/kg spice using a self-contained, slow-release ClO2 media in a rotating tumbler for 12 h. Immediately after treatment, and at days 1, 10, and 30 post-treatment, samples were plated to enumerate surviving Salmonella.
Results: When compared to the control treatment, each concentration of ClO2 was effective in reducing Salmonella contamination for all three spices tested. Out of the three different concentrations of ClO2 tested, 500 mg/kg decreased Salmonella levels by > 2.0 logs at day 0. Salmonella levels stayed relatively consistent across the first 10 days of post-treatment storage, but levels decreased by at least an additional 0.5 logs by day 30.
Significance: Chlorine dioxide gas provides a quality, non-heat alternative treatment, especially for smaller-scale operations to reduce Salmonella contamination in spices. The versatility of being able to use the treatment at many points in the supply chain also makes it desirable.