Spray Washing of Tomatoes with Chlorine Dioxide To Minimize Salmonella on Inoculated Fruit Surfaces and Cross-Contamination from Revolving Brushes

摘要

Chlorine dioxide (ClO_2) is an antimicrobial agent available for commercial produce washing. This study examined the efficacy of ClO_2 at 5 parts per million (ppm) during spray washing of tomatoes (5.0 ml/s per fruit) for preventing Salmonella enterica transfer from inoculated roller brushes to fruit and wash runoff. Furthermore, the sanitizing effects of ClO_2 during spray washing at low and high flow rates (5.0 and 9.3 ml/s per fruit, respectively) on tomato surfaces (nonstem scar areas) with either newly introduced (wet) or overnight air-dried Salmonella inocula were investigated. Salmonella transfer from contaminated brushes to fruit surfaces was reduced 2.1 ± 0.6 or 4.7 ± 0.2 log cycles after spray washing with water for 40 s or with the ClO_2 solution for 10 s, respectively. Cross-contamination of Salmonella from brushes to wash runoff during fruit washing for 60 s decreased 5.9 ± 0.3 log cycles when ClO_2 was used. Fruit washing using contaminated brushes and low flow-rate washing with either water or ClO_2 solution for 10 s reduced newly introduced Salmonella on fruit surfaces by 1.7 ± 0.6 or 5.1 ± 0.3 log cycles, respectively. For fruit surfaces with air-dried inocula, washing with water and using uncontaminated brushes for 10 to 40 s reduced Salmonella by 3.2 ± 0.3 to 3.4 ± 0.4 log cycles; and the reduction was significantly improved by using ClO_2, high flow rate, or a longer washing time. Washing with ClO_2 at tested flow rates for 10 to 60 s resulted in a 4.4 ± 0.6 to 5.2 ± 0.1 log reduction of air-dried Salmonella on fruit surfaces.