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Pabst CR, Kharel K, De J, Bardsley CA, Bertoldi B, Schneider KR. Evaluating the efficacy of peroxyacetic acid in preventing Salmonella cross-contamination on tomatoes in a model flume system. Heliyon 2024; 10:e31521. [PMID: 38813225 PMCID: PMC11133892 DOI: 10.1016/j.heliyon.2024.e31521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 05/14/2024] [Accepted: 05/17/2024] [Indexed: 05/31/2024] Open
Abstract
The use of flume tanks for tomato processing has been identified as a potential source of cross-contamination, which could result in foodborne illness. This study's objective was to assess the efficacy of peroxyacetic acid (PAA) at a concentration of ≤80 mg/L in preventing Salmonella enterica cross-contamination under various organic loads in a benchtop model tomato flume tank. The stability of 80 mg/L PAA at different chemical oxygen demand (COD) levels was also tested. Tomatoes were spot inoculated with a five-serovar rifampin-resistant (rif+) Salmonella cocktail (106 or 108 colony forming unit (CFU)/tomato). Inoculated (n = 3) and uninoculated (n = 9) tomatoes were introduced into the flume system containing 0-80 mg/L PAA and 0 or 300 mg/L COD. After washing for 30, 60, or 120 s, uninoculated tomatoes were sampled and analyzed for cross-contamination. All experiments were conducted in triplicate. Increasing the organic load (measured as COD) affected the stability of PAA in water with significantly faster dissociation when exposed to 300 mg/L COD. The concentration of PAA, inoculum level, COD levels, and time intervals were all significant factors that affected cross-contamination. Cross-contamination occurred at the high inoculum level (108 CFU/tomato) even when 80 mg/L PAA was present in the model flume tank, regardless of the organic load level. When the tomatoes were contaminated at a level of 106 CFU/tomato, concentrations as low as 5 mg/L of PAA were effective in preventing cross-contamination at 0 mg/L COD; however, 100 % tomatoes (9/9) were positive when the organic load increased to 300 mg/L COD. When the PAA concentration was increased to 10 mg/L, it effectively prevented cross-contamination in the tank, regardless of the presence of organic load. These results suggest that using PAA at concentrations below the maximum limit remains effective in limiting bacterial cross-contamination and offers a more environment-friendly option for tomato packinghouse operators.
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Affiliation(s)
- Christopher R. Pabst
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, FL, 32611, USA
| | - Karuna Kharel
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, FL, 32611, USA
| | - Jaysankar De
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, FL, 32611, USA
- Department of Microbiology & Cell Science, University of Florida, Gainesville, FL, 32611, USA
| | - Cameron A. Bardsley
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, FL, 32611, USA
- USDA-ARS Southeastern Fruit and Tree Nut Research Station, Byron, GA, 31008, USA
| | - Bruna Bertoldi
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, FL, 32611, USA
| | - Keith R. Schneider
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, FL, 32611, USA
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Bertoldi B, Bardsley CA, Pabst CR, Baker CA, Gutierrez A, De J, Luo Y, Schneider KR. Influence of Free Chlorine and Contact Time on the Reduction of Salmonella Cross-Contamination of Tomatoes in a Model Flume System. J Food Prot 2022; 85:22-26. [PMID: 34469547 DOI: 10.4315/jfp-21-212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/01/2021] [Indexed: 11/11/2022]
Abstract
ABSTRACT The process of washing tomatoes in dump (flume) tanks has been identified as a potential source of cross-contamination. This study's objective was to assess the potential for Salmonella enterica cross-contamination at various inoculation levels in the presence of free chlorine (HOCl) and organic matter. Uninoculated tomatoes were introduced into a laboratory-based model flume containing tomatoes inoculated with a cocktail of five rifampin-resistant S. enterica serovars at 104, 106, or 108 CFU per tomato in water containing 0 or 25 mg/L HOCl and 0 or 300 mg/L chemical oxygen demand (COD). Uninoculated tomatoes exposed to the inoculated tomatoes were removed from the water after 5, 30, 60, and 120 s and placed in bags containing tryptic soy broth supplemented with rifampin and 0.1% sodium thiosulfate. Following incubation, enrichment cultures were plated on tryptic soy agar supplemented with rifampin and xylose lysine deoxycholate agar to determine the presence of Salmonella. HOCl and pH were measured before and after each trial. The HOCl in water containing 300 mg/L COD significantly declined (P ≤ 0.05) by the end of each 120-s trial, most likely due to the increased demand for the oxidant. Higher inoculum levels and lower HOCl concentrations were significant factors (P ≤ 0.05) that contributed to increased cross-contamination. At 25 mg/L HOCl, no Salmonella was recovered under all conditions from uninoculated tomatoes exposed to tomatoes inoculated at 104 CFU per tomato. When the inoculum was increased to 106 and 108 CFU per tomato, cross-contamination was observed, independent of COD levels. The results from this study indicate that the currently required sanitizer concentration (e.g., 100 or 150 mg/L) for flume water may be higher than necessary and warrants reevaluation. HIGHLIGHTS
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Affiliation(s)
- Bruna Bertoldi
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611
| | - Cameron A Bardsley
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611
| | - Christopher R Pabst
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611
| | - Christopher A Baker
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611
| | - Alan Gutierrez
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611
| | - Jaysankar De
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611
| | - Yaguang Luo
- U.S. Department of Agriculture, Agricultural Research Service, Environmental Microbial and Food Safety Laboratory, Beltsville, Maryland 20705, USA
| | - Keith R Schneider
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611
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