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Gongora K, Vankerschaver J, Sampers I, Van Haute S. The influence of pH on the efficacy of oxidation-reduction potential (ORP) to predict chlorine disinfection of surrogate bacteria, Escherichia coli O157:H7 and Listeria monocytogenes in oxidant demand free conditions and fresh produce wash water. Food Microbiol 2024; 121:104516. [PMID: 38637078 DOI: 10.1016/j.fm.2024.104516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 03/06/2024] [Accepted: 03/07/2024] [Indexed: 04/20/2024]
Abstract
Oxidation-reduction potential (ORP) is commonly used as a rapid measurement of the antimicrobial potential of free chlorine during industrial fresh produce washing. The current study tested the hypothesis that ORP can act as a "single variable" measurement of bacterial (vegetative and endospores) inactivation effectiveness with free chlorine irrespective of the water pH value. This situation has on occasion been assumed but never confirmed nor disproven. Chlorine-dosed pH 6.5 and 8.5 phosphate buffer solutions were inoculated with Escherichia coli (E. coli), Listeria innocua (L. innocua), or Bacillus subtilis (B. subtilis) endospores. ORP, free chlorine (FC), and log reduction were monitored after 5 s (for E. coli and L. innocua) and up to 30 min (for B. subtilis spores) of disinfection. Logistic and exponential models were developed to describe how bacteria reduction varied as a function of ORP at different pH levels. Validation tests were performed in phosphate buffered pH 6.5 and 8.5 cabbage wash water periodically dosed with FC, cabbage extract and a cocktail of Escherichia coli O157:H7 (E. coli O157:H7) and Listeria monocytogenes (L. monocytogenes). The built logistic and exponential models confirmed that at equal ORP values, the inactivation of the surrogate strains was not consistent across pH 6.5 and pH 8.5, with higher reductions at higher pH. This is the opposite of the well-known free chlorine-controlled bacterial inactivation, where the antibacterial effect is higher at lower pH. The validation test results indicated that in the cabbage wash water, the relationship between disinfection efficiency and ORP was consistent with the oxidant demand free systems. The study suggests that ORP cannot serve as a reliable single variable measurement to predict bacterial disinfection in buffered systems. When using ORP to monitor and control the antibacterial effectiveness of the chlorinated wash water, it is crucial to take into account (and control) the pH.
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Affiliation(s)
- Kimberly Gongora
- Laboratory of Food Microbiology and Biotechnology, Department of Food Technology, Safety and Health, Ghent University, 9000, Ghent, Belgium; Center for Food Biotechnology and Microbiology, Ghent University Global Campus, Incheon, 21985, South Korea
| | - Joris Vankerschaver
- Center for Biosystems and Biotech Data Science, Ghent University Global Campus, Incheon, 21985, South Korea; Department of Applied Mathematics, Computer Science and Statistics, Ghent University, 9000, Ghent, Belgium
| | - Imca Sampers
- Laboratory of Food Microbiology and Biotechnology, Department of Food Technology, Safety and Health, Ghent University, 9000, Ghent, Belgium; Research Unit VEG-i-TEC, Department of Food Technology, Safety and Health, Ghent University, Campus Kortrijk, Sint-Martens-Latemlaan 2B, 8500, Kortrijk, Belgium
| | - Sam Van Haute
- Laboratory of Food Microbiology and Biotechnology, Department of Food Technology, Safety and Health, Ghent University, 9000, Ghent, Belgium; Center for Food Biotechnology and Microbiology, Ghent University Global Campus, Incheon, 21985, South Korea.
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Li C, Sun W, Liu S, Pan C, Wang D, Feng Y, Cen J, Chen S. Efficient aluminum removal and microorganism inhibition in ready-to-eat jellyfish by slightly acidic electrolyzed water. FOOD BIOSCI 2023. [DOI: 10.1016/j.fbio.2023.102599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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Xu J, Xu Y, Guan X, Yang G, Wang S. Effects of sequential treatments using radio frequency energy and ultraviolet light on inactivation of Bacillus cereus spores and quality attributes of buckwheat. Int J Food Microbiol 2023; 385:109997. [DOI: 10.1016/j.ijfoodmicro.2022.109997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/29/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022]
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Zhang C, Yang G, Shen P, Shi Y, Yang Y, Liu Y, Xia X, Wang S. Inactivation mechanism of slightly acidic electrolyzed water on Bacillus cereus spores. Food Microbiol 2022; 103:103951. [DOI: 10.1016/j.fm.2021.103951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 09/11/2021] [Accepted: 11/19/2021] [Indexed: 01/18/2023]
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