title: Inactivation of Salmonella enterica and Listeria monocytogenes inoculated on hydroponic tomatoes using chlorine dioxide gas.
abstract: The main objective of this study was to determine survivability of a cocktail of three strains of Salmonella enterica (Montevideo, Javiana, and Baildon) and two strains of Listeria monocytogenes (LCDC 81-861 and F4244) on hydroponic tomatoes after treatment with chlorine dioxide (ClO(2)) gas. An initial concentration of 8-9 log cfu/mL of Salmonella and Listeria cocktails was inoculated individually, in separate experiments, on tomato skin to obtain a population of 7-8 log cfu/cm(2) after drying of the inoculums on the tomato skin. The aim was to achieve a 5 log reduction consistent with the recommendations of the National Advisory Committee on Microbiological Criteria for Foods. The tomato skins were treated with 0.1, 0.3, and 0.5 mg/L ClO(2) gas for 12 min at 22 degrees C and at the relative humidity of 90%. Untreated skin samples were processed under the same conditions. ClO(2)-gas-treated and untreated samples were recovered by an overlay method. The bottom layer contains tryptic soy agar, and the top layer consists of xylose-lysine-desoxycholate agar or modified Oxford antimicrobial supplement agar for Salmonella and Listeria, respectively. More than a 5 log reduction in Salmonella and Listeria was observed on the tomato skin surfaces after treatment with 0.5 mg/L ClO(2) gas for 12 min. Treatment with 0.5 mg/L ClO(2) gas for 12 min also delayed the growth of natural microflora on tomato surfaces and extended the shelf life of tomatoes by 7 days during storage at 22 degrees C, compared with the untreated control. These results revealed that ClO(2) gas is a promising antimicrobial technology for fresh tomato skin surfaces.
authors.affiliation: Department of Food Science, Purdue University, West Lafayette, Indiana 47907-1160, USA.
authors.forename: Arpan
authors.initials: A
authors.lastname: Bhagat
authors.forename: Barakat S M
authors.initials: BS
authors.lastname: Mahmoud
authors.forename: Richard H
authors.initials: RH
authors.lastname: Linton
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000032:analysis; D017606:Chlorine Compounds / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology; D004203:Disinfection / Q000379:methods* / Q000592:standards; D005511:Food Handling; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D005517:Foodborne Diseases / Q000517:prevention & control; D005638:Fruit / Q000737:chemistry / Q000382:microbiology; D005658:Fungi / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification; D018527:Hydroponics; D007700:Kinetics; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000302:isolation & purification; D018551:Solanum lycopersicum / Q000737:chemistry / Q000382:microbiology*; D050296:Microbial Viability / Q000187:drug effects*; D010087:Oxides / Q000494:pharmacology*; D010858:Pigmentation / Q000187:drug effects; D011786:Quality Control; D019779:Salmonella enterica / Q000187:drug effects* / Q000302:isolation & purification; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C025109:chlorine dioxide; D001205:Ascorbic Acid