Efficacy of Residual Ozone on Surrogate Microorganisms for Waterborne Pathogens in Bottled Water

Ozone is a powerful disinfectant that is widely used in the bottled water (BW) industry. Primary ozone disinfection of water for bottling occurs in a reaction tank with a specific contact time. Residual ozone in the bottled water may still possess disinfection activity. The purpose of this study was...

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Main Authors: William Ryan Schwaner, Sanjay Kumar, Harshavardhan Thippareddi
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Journal of Food Protection
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Online Access:http://www.sciencedirect.com/science/article/pii/S0362028X25000675
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author William Ryan Schwaner
Sanjay Kumar
Harshavardhan Thippareddi
author_facet William Ryan Schwaner
Sanjay Kumar
Harshavardhan Thippareddi
author_sort William Ryan Schwaner
collection DOAJ
description Ozone is a powerful disinfectant that is widely used in the bottled water (BW) industry. Primary ozone disinfection of water for bottling occurs in a reaction tank with a specific contact time. Residual ozone in the bottled water may still possess disinfection activity. The purpose of this study was to evaluate the efficacy of residual ozone in BW in reducing the populations of surrogate microorganisms for waterborne pathogens (Escherichia coli [BAA-1427], Enterococcus faecalis [ATCC 19433] and Burkholderia cepacia [ATCC 25416]). The effect of water pH and total dissolved solids (TDS) on the disinfection process was also evaluated. A pilot scale ozone delivery system and filler were assembled to allow filling of 0.5 L polyethylene terephthalate (PET) plastic water bottles with ozonated (0.1, 0.2, 0.3, and 0.4 mg/L) water. Ozonated water was inoculated with microorganisms to attain ca. 6.0 log and 4.0 log CFU/mL, and microbial populations were determined after 5, 30, 60, and 180 min at 25 °C. Samples (100 mL) were filtered through Neogen NEO-GRID membrane filters and placed on tryptic soy agar, incubated for 48 h at 37 °C, and enumerated. Ozone dissipation in BW was measured with and without biological load (6.0 log CFU/mL) at 21 and 38°C for 6 h. Greater reductions (P ≤ 0.05) in E. faecalis (4.61 and 3.68 log CFU/mL) and B. cepacia (5.24 and 4.12 log CFU/mL) were observed at 0.4 and 0.1 mg/L ozone in BW, respectively. Longer contact time (>5 min) did not result in greater reduction (P > 0.05) in microbial populations. Faster ozone dissipation (P ≤ 0.05) was observed at 38 °C and the dissipation rate increased with biological load. Except at higher pH (9.0) and TDS (50 and 300 mg/L) concentrations, the residual ozone in BW (≥0.1 mg/L) can provide ≥4.0 log reductions in pathogen surrogates E. coli, E. faecalis, and B. cepacia, providing an additional measure of microbiological safety in BW.
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spelling doaj-art-daaa2e352f7f43cfa00e91de894199ac2025-08-20T03:13:29ZengElsevierJournal of Food Protection0362-028X2025-05-0188610051510.1016/j.jfp.2025.100515Efficacy of Residual Ozone on Surrogate Microorganisms for Waterborne Pathogens in Bottled WaterWilliam Ryan Schwaner0Sanjay Kumar1Harshavardhan Thippareddi2Department of Food Science and Technology, University of Nebraska, Lincoln, NE 68588, United States; Quality Assurance and Food Safety, Niagara Bottling LLC, Diamond Bar, CA 91765, United StatesQuality Assurance and Food Safety, Niagara Bottling LLC, Diamond Bar, CA 91765, United States; Corresponding author.Department of Poultry Science, University of Georgia, Athens, GA 30602, United StatesOzone is a powerful disinfectant that is widely used in the bottled water (BW) industry. Primary ozone disinfection of water for bottling occurs in a reaction tank with a specific contact time. Residual ozone in the bottled water may still possess disinfection activity. The purpose of this study was to evaluate the efficacy of residual ozone in BW in reducing the populations of surrogate microorganisms for waterborne pathogens (Escherichia coli [BAA-1427], Enterococcus faecalis [ATCC 19433] and Burkholderia cepacia [ATCC 25416]). The effect of water pH and total dissolved solids (TDS) on the disinfection process was also evaluated. A pilot scale ozone delivery system and filler were assembled to allow filling of 0.5 L polyethylene terephthalate (PET) plastic water bottles with ozonated (0.1, 0.2, 0.3, and 0.4 mg/L) water. Ozonated water was inoculated with microorganisms to attain ca. 6.0 log and 4.0 log CFU/mL, and microbial populations were determined after 5, 30, 60, and 180 min at 25 °C. Samples (100 mL) were filtered through Neogen NEO-GRID membrane filters and placed on tryptic soy agar, incubated for 48 h at 37 °C, and enumerated. Ozone dissipation in BW was measured with and without biological load (6.0 log CFU/mL) at 21 and 38°C for 6 h. Greater reductions (P ≤ 0.05) in E. faecalis (4.61 and 3.68 log CFU/mL) and B. cepacia (5.24 and 4.12 log CFU/mL) were observed at 0.4 and 0.1 mg/L ozone in BW, respectively. Longer contact time (>5 min) did not result in greater reduction (P > 0.05) in microbial populations. Faster ozone dissipation (P ≤ 0.05) was observed at 38 °C and the dissipation rate increased with biological load. Except at higher pH (9.0) and TDS (50 and 300 mg/L) concentrations, the residual ozone in BW (≥0.1 mg/L) can provide ≥4.0 log reductions in pathogen surrogates E. coli, E. faecalis, and B. cepacia, providing an additional measure of microbiological safety in BW.http://www.sciencedirect.com/science/article/pii/S0362028X25000675Bottled WaterDisinfectionOzoneSurrogate bacteria
spellingShingle William Ryan Schwaner
Sanjay Kumar
Harshavardhan Thippareddi
Efficacy of Residual Ozone on Surrogate Microorganisms for Waterborne Pathogens in Bottled Water
Journal of Food Protection
Bottled Water
Disinfection
Ozone
Surrogate bacteria
title Efficacy of Residual Ozone on Surrogate Microorganisms for Waterborne Pathogens in Bottled Water
title_full Efficacy of Residual Ozone on Surrogate Microorganisms for Waterborne Pathogens in Bottled Water
title_fullStr Efficacy of Residual Ozone on Surrogate Microorganisms for Waterborne Pathogens in Bottled Water
title_full_unstemmed Efficacy of Residual Ozone on Surrogate Microorganisms for Waterborne Pathogens in Bottled Water
title_short Efficacy of Residual Ozone on Surrogate Microorganisms for Waterborne Pathogens in Bottled Water
title_sort efficacy of residual ozone on surrogate microorganisms for waterborne pathogens in bottled water
topic Bottled Water
Disinfection
Ozone
Surrogate bacteria
url http://www.sciencedirect.com/science/article/pii/S0362028X25000675
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AT sanjaykumar efficacyofresidualozoneonsurrogatemicroorganismsforwaterbornepathogensinbottledwater
AT harshavardhanthippareddi efficacyofresidualozoneonsurrogatemicroorganismsforwaterbornepathogensinbottledwater