Effectiveness of Individual or Combined Sanitizer Treatments for Inactivating Salmonella spp. on Smooth Surface, Stem Scar, and Wounds of Tomatoes

Abstract

ABSTRACT: Unwaxed, green tomatoes (‘Florida 47’ cultivar) were contaminated with Salmonella and then treated with aqueous solutions of sodium hypochlorite (HOCl; 200 ppm), acidified sodium chlorite (ASC; 1200 ppm), peroxyacetic acid (PAA; 87 ppm), or chlorine dioxide gas (ClO2; total 100 mg). Additionally, a combined treatment of immersion in HOCl, followed by immersion in ASC and then exposure to ClO2 gas was investigated. Tomatoes were spot inoculated with a 5-strain Salmonella cocktail on smooth surfaces, stem scar tissue, or puncture wounds. A 3 replicate set of each of the sample groups was stored at 20 °C and 95% relative humidity (RH) and retested after 5 d. Greater than 4.0-log unit reductions of Salmonella spp. inoculated on the smooth surface of the tomatoes were seen for all aqueous sanitizer treatments, with Salmonella populations below the detection limit after 5 d of storage. All aqueous treatment groups showed > 1.0-log unit reductions in Salmonella at the stem scar and >2.0-log unit reduction at puncture wounds. The ClO2 gas treatment reduced Salmonella to undetectable levels at the stem scar, but had no apparent effect on populations inoculated in puncture wounds. The combined treatment resulted in a 3.0-log unit reduction of inoculated Salmonella at puncture wounds. In all cases except for treatment with chlorine, surviving Salmonella populations did not increase after the 5 d of storage. Results of this study suggest the combined treatment was most effective for minimizing the risk of Salmonella contaminated on tomatoes.