Since its discovery in the early 1800s, ozone has been proven to be an efficacious sanitizer, disinfectant, and antimicrobial oxidizing agent. The disinfecting capability of 1 ppm (mg/L) of ozone dissolved in water (aqueous ozone) is equivalent to many times (10 to 4,000 times) the concentration of free available chlorine. Ozone has been proven to be effective at oxidizing microorganisms such as viruses and bacteria because its method of oxidation prevents them from developing a tolerance to ozone. In bacteria, ozone rips electrons away from the disaccharides and amino acids that comprise the cell wall. This causes lysis or bursting of the wall, effectively destroying the organism. In viruses, ozone oxidizes DNA and RNA which are ineffectively protected by a thin protein coat.
Ozone is a resonant molecule comprised of three oxygen atoms. The third atom is weakly bonded and electron deficient, causing the molecule to be unstable which consequently makes the ozone molecule an effective sanitizer, disinfectant, and oxidizer. Because of ozone’s instability as a gas, it cannot be stored and must, therefore, be generated onsite near its point of use. It is produced via an ozone generator which utilizes a dry, oxygen-enriched feed gas and electricity. As the feed gas passes through the generator, the electrical energy causes some of the oxygen (O2) molecules to split, resulting in two singlet oxygen atoms (O1). These singlet atoms (O1) unite with other oxygen molecules (O2) to produce ozone (O3).
When ozone gas is dissolved in water, its half-life can range from seconds to hours, depending upon the pH, temperature, level, and type of contaminants in the water. Ozone oxidation of dissolved organic contaminants typically results in the formation of oxygen, carbon dioxide, and smaller, more biodegradable molecular fragments.
Ozone vs. Traditional Sanitizers
Ozone’s antimicrobial efficacy, as measured in electron volts, is superior to commercial sanitation products commonly used in today’s modern food facilities. No other sanitation or disinfection chemical is stronger or more efficacious than ozone in terms of its oxidative power.
Ozone has been widely studied over the past century for its disinfection efficacy and its superior strength to commonly used chlorine-based chemicals.
Values of Specific Coefficients of Lethality for the Main Disinfectants (L/mg/min)
CT values (mg=min/L) for 99% Inactivation of Microorganisms with Disinfectants at 5°C.
Log reduction time (LRT): time (in seconds) required to reduce bacterial populations by log 1 at 21-23°C
Ozone has been documented to be significantly more effective than all the commonly-used sanitation chemicals available for commercial and industrial sanitation. It is unsurpassed for its antimicrobial efficacy and is superior in terms of microbial log reduction. Also, given proper safety, material selection, and environmental controls, it demonstrates no negative impacts on the facilities, products, or employees. Ozone treatment is a uniquely safe and sustainable non-thermal sanitation process.
For application control, gaseous ozone is dissolved in water to create “ozone-enriched water” which is commonly referred to as aqueous ozone. Aqueous ozone can be utilized at several points of the process, depending on the commodity. The most common uses in the food industry are direct contact with the food product and/or surface sanitation and CIP/SIP. Since ozone is an approved food additive, it has the unique capability of providing sanitation to food and equipment simultaneously (i.e. food product on a conveyor belt). Ozone creates no organoleptic changes in food products (through direct or indirect contact), as traditional chemicals can and do. Ozone helps to remove residual pesticides and microorganisms such as E. coli, Listeria monocytogenes, Salmonella choleraesuis, Campylobacter jejuni, and Bacillus subtilis, etc. from food products.
Ozone-enriched water can sanitize both food contact and non-food contact surfaces, as well as any other wettable area with sanitation needs. The use of ozone can reduce levels of fat, oil, and grease on surfaces, as well as break down bacterial biofilm build-up, molds, and mildew (particularly in areas of high sugar products). With continued use, ozone will sanitize floor drains and rid the drains and plumbing of biofilm and other microorganisms that can migrate back into the processing area (especially Listeria monocytogenes) with the benefit of adding dissolved oxygen to the wastewater and no adverse effects on wastewater treatment systems.
With increased interest in adopting more sustainable practices, increasing consumer demand for more organic and healthy food options, as well as much stricter food safety rules (i.e. FSMA, HAACP, and HARPC), the use of ozone has accelerated the move away from multi-chemical based sanitation treatments. Other events, including water availability and cost, food recalls, foodborne illnesses, wastewater concerns, and the need to reduce operating costs, have advanced the use of ozone-based technology either as a replacement for or in addition to traditional chemical-based and thermal-based sanitation treatments. Ozone is an FDA, USDA, and USDA Organic approved antimicrobial food additive. It is an EPA approved antimicrobial oxidizer for potable water, surface sanitation, and CIP/SIP.
Below is a summary of the current regulatory information on ozone use in the food industry by agency. Additional documentation further describing the regulations in detail can be found at the end of this document (Regulatory Documentation).
- FDA – Regulates and allows ozone contact with foods (F&V, seafood, shell eggs, bottled water)
- USDA/FSIS – Regulates and allows ozone contact with meat, poultry, and egg products
- USDA National Organic Program (NOP) – Allows ozone for organic food contact
- EPA/FIFRA – Regulates ozone generators under their device program (sanitation and potable water)
- OSHA – Regulates ozone (for worker exposure) in workplace air
21 § CFR 129.80 (3/15/1977; amended 4/4/2012)
Bottled water plant sanitizing of contact surfaces and any other critical area
0.1 PPM ozone-enriched water solution for at least five minutes (Ct value of 0.5 mg-min/L)
21 CFR §173.368 (6/26/2001)
FDA Secondary Direct Food Additives Permitted in Food for Human Consumption
Ozone may be safely used in the treatment, storage, and processing of foods, including meat and poultry
Ozone is used as an antimicrobial agent in accordance with current industry standards of good manufacturing practice
21 § CFR 178.1010 (b) (1, 3, 9, 30, 38) (3/16/1977)
“Category Three Certification”: <15 cfu per cm for Yeast, Mold, Bacteria; No rinse
§178.1010 (b): “The solutions consist of one of the following, to which may be added components generally recognized as safe (GRAS) and components which are permitted by prior sanction or approval.”
- (1) 200 PPM chlorine
- (3) 25 PPM iodine (iodophore)
- (9) 200 PPM quaternary ammonia compound
- (30) 400-600 PPM peroxide
- (38) 128-156 PPM peroxyacetic acid
Ozone is (GRAS) and listed under prior sanction (USEPA/FIFRA) Standard Dose 1-3 PPM Ozone
November 27, 2001, the American Meat Institute filed a letter with USDA/FSIS requesting interpretation of the scope of the FDA rule allowing the use of ozone as an antimicrobial agent USDA/FSIS determined that, “The use of ozone on raw and ready-to-eat meat and poultry products just prior to packaging is acceptable,” and that there are “no labeling issues in regard to treated product.”
USDA/FSIS Directive 7120.1 (12/17/02) (Revised 3/3/16)
“The attachment below identifies the substances that have been accepted since January 2000 by FSIS as safe and suitable for use in the production of meat and poultry products.”
(Attachment 1) Antimicrobial – Ozone
- All Meat and Poultry Products
- In accordance with current industry standards of good manufacturing practice
- Reference 21 CFR § 173.368
USDA National Organic Program (NOP) Allowed Substances
Ozone is listed in the NOP Final Rule (§ 205.605 (b) (20) pg. 437 – Nonagricultural (non-organic) substances allowed as ingredients in or on processed products labeled as “organic” or “made with organic (specified ingredients or food group(s))”
(b) Synthetics allowed: (20) ozone
Food Safety and Inspection Service New Technology Information Table Last Updates January 25, 2017
Listed technology: Ozone
FSIS Compliance Guideline: Controlling Listeria monocytogenes in Post-lethality Exposed Ready-to-Eat Meat and Poultry Products – January 2014
Post-lethality Treatments and Antimicrobial Agents
Buege, D.R., Ingham, S.C. and J.A. Losinski (University of Wisconsin-Madison), “Evaluation of Del Ozone’s Delzone® Sanitation System as a Post-Lethality Treatment to Control Listeria monocytogenes Contamination on Ready-To-Eat Meat Products”, Confidential Report to Del Ozone, April 16, 2004.
Use of Antimicrobial Ingredients including Bacteriophages, Lactates, Acetates, Diacetates, and Ozone
Ozone is an antimicrobial gas usually applied in an aqueous solution to products, food contact surfaces as a continuous spray (e.g., belts, moving tables), and nonfood contact environmental surfaces. Currently, the use of ozone is permitted by FDA and FSIS (21 CFR 173.368, FSIS Directive 7120.1) for use with all meat and poultry products, including RTE meat and poultry products.
Buege et al., (2004) showed 1.0 to 2.4 log reductions (average 1.5) of Lm when 0.6 ppm ozone for 30 seconds was applied to ham, salami, meatloaf, natural casing wieners, and skinless wieners.
FSIS USDA Training – Process Category Introduction 3/25/2015 Inspection
Poultry Slaughter – Antimicrobial Interventions
Raw Product – Intact Processing Category
Common Controls – Biological
In addition to the controls that may have already been used during the slaughter process, establishments commonly utilize additional antimicrobial interventions for pathogens of concern.
On August 21, 2014, FSIS published the Modernization of Poultry Slaughter Inspection final rule. FSIS Notice 50-14 addresses how IPP are to verify compliance with approved online and offline reprocessing antimicrobial intervention systems. Establishments that slaughter poultry other than ratites are allowed to use these approved systems to clean carcasses accidentally contaminated with digestive tract contents (9 CFR 381.91). A list of approved systems is included as an attachment to this notice.
Ozone may be used in contact with food as a gas or liquid as an antimicrobial in meat and poultry products, including ground meats.
EPA/FIFRA Office of Pesticide Programs (OPP) Disinfectant Technical Science Section (DIS/TSS)
EPA regulates ozone as a pesticide-producing device.
Ozone generators must be registered by the EPA under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).
Each Ozone Generator Manufacturer has a unique EPA registered establishment number as a pesticide-producing device.
For no-rinse surface sanitation compliance, the USEPA/FIFRA Office of Pesticide Programs (OPP) Disinfectant Technical Science Section (DIS/TSS) requires:
- Antimicrobial efficacy data determined by AOAC International methods
- Toxicological profiles
- Environmental impact information
- Specific label information and directions for use
Ozone Generators are recognized by the EPA as antimicrobial producing devices per EPA documentation published in 1976, with an EPA Establishment Number necessary for compliance.
OSHA has two ozone standards to protect plant workers from exposure to harmful levels of ozone in facility air:
- Permissible Exposure Level (PEL) – 0.1 PPM ozone (by volume). Time-weighted average over an 8-hour work day, 5-days per week
- Short-Term Exposure Level (STEL) – 0.3 PPM ozone (by volume) for no longer than 15-minutes, not to be exceeded more than four times per day.
These OSHA standards have been adopted worldwide wherever ozone is used commercially.
Adherence to these allowable ozone exposures ensures that workers will never be exposed to toxic levels of gaseous ozone during working hours.