A review of ozone used in food and beverage processing

Ozone has a long-standing reputation as a reliable disinfectant in the food and beverage industry. In 1982, the use of ozone for disinfecting bottled water was deemed safe in the United States, and was later approved for use in sanitizing bottled water treatment lines. In countries like Australia, France, and Japan, ozone processing for food has been in use for some time. However, it wasn’t until 2001 that the FDA approved the use of ozone for direct contact with food, under the Final Rule 21 CFR Part 173.336. The USDA’s Food Safety Inspection Service also approved ozone for use on meat and poultry products later that same year. This resulted in the installation of many commercial systems that use ozone as an antimicrobial agent for direct contact with food. Ozone is also listed in the National Organic Program’s final rule, and is therefore permitted for use in organic or made with organic food products.

Ozone is a highly reactive form of oxygen, consisting of three oxygen atoms. It is known for its role in the stratosphere, where it helps to protect the Earth from harmful radiation, and for being formed during lightning discharges in the atmosphere. As a potent disinfectant, ozone decomposes into hydroxyl, hydroperoxy, and superoxide radicals. These short-lived free radicals are highly oxidizing and are capable of inactivating pathogens like Salmonella enteritidis, E. coli O157:H7, Listeria monocytogenes, Shigella dysenteriae, and Chlostridium botulinum, as well as various yeasts, fungi, viruses, parasites, and molds.

Ozone is more effective than chlorine as an antimicrobial agent due to its stronger oxidation-reduction potential of 2.07V compared to chlorine’s 1.36V. Additionally, ozone is environmentally friendly and leaves no harmful chemical residues. Ozone is soluble in water, with its solubility being affected by temperature, and decreases with increasing temperature. Although ozone degrades quickly, it has a longer half-life in the gaseous state than in an aqueous solution, and the purity of the water affects the half-life, with impure water causing faster degradation. These properties of ozone are crucial in the design of food processing equipment to effectively generate and treat food with ozone.

Ozone Processing

Ozone is a highly effective antimicrobial agent that can be utilized in the safe treatment, storage, and processing of foods in line with good manufacturing practice standards in the industry. Ozone can be produced through photochemical or corona discharge (plasma) techniques, with the latter being the most commonly used method.

In corona discharge (CD) generation, dry air or oxygen is passed between electrodes coated with a dielectric material, leading to the breakdown of oxygen molecules into charged atoms that form ozone molecules. The quality of the air or oxygen used is crucial to the performance and longevity of the CD ozone generator.

Another method of ozone production is through photochemical reactions utilizing ultraviolet (UV) light. Low-pressure mercury UV lamps emitting 185 nm wavelength can be used to generate ozone through photodissociation of oxygen molecules into ozone molecules.

Ozone produced through either method can be applied to foods or food contact surfaces in the form of gaseous ozone or aqueous ozone solutions to decontaminate. Both types of ozone generators are commercially available and can be purchased from companies such as Ozone Safe Food Technologies, Oxidation Technologies, and DEL Ozone. The Ohio State University also offers a range of ozone generators and product treatment chambers ranging from benchtop to pilot-scale.

For aqueous applications, ozone is transferred into water using Venturi injection or fine bubble diffusion. Venturi injection involves converting water pressure into kinetic energy, while fine bubble diffusers distribute a fine dispersion of ozone gas bubbles into the water column.

The advantage of onsite ozone generation is that it eliminates the need for personnel to handle harmful chemicals for sanitation purposes. Additionally, ozone does not require storage or special handling, unlike other chemical sanitizers.

However, high concentrations of ozone can have a strong odor and pose a health risk, and must be regulated by OSHA for permissible levels of exposure in commercial manufacturing facilities.

Applications of Ozone Processing to Foods

• Direct Food Contact.

Ozone is an effective way to improve safety and extend the shelf life of many types of food. Foods can be treated with ozone in both gaseous and aqueous forms. The sanitation of fresh produce is a particularly promising application of ozone, as it is gentle on the produce and can be used at high levels without affecting taste or appearance. Additionally, ozone reduces the levels of spoilage microorganisms in wash water, which can extend the shelf life of produce and conserve water usage. In seafood processing, ozone has been used for many years and has been shown to not only enhance the safety of seafood, but also to increase its shelf life.

It is important to note that different types of food require different concentrations of ozone. High-fat foods such as meat and chicken need higher ozone concentrations, while low-fat foods like fruits and vegetables can be treated with lower concentrations. When treating meat and chicken, it is crucial to avoid using excess ozone, as it can cause oxidation and negatively impact the flavor of the products.

• Surface Sanitation.

Another area where ozone is widely used is for sanitizing food-contact surfaces. Incorporating ozone-infused water into clean-in-place (CIP) procedures provides food processors with a more efficient and effective way to sanitize their plant surfaces. Ozone-infused water can be used as a sanitizing rinse for food-contact surfaces like cutting tables and for non-food-contact surfaces like floors. It can also be utilized for surface disinfection of aseptic food packaging materials.

• Cold Storage

Ozone can be used in cold storage of food products to maintain their freshness and extend their shelf life. In cold storage, ozone helps to control the growth of bacteria, mold, yeast, and other microorganisms that can spoil the food and cause it to spoil quickly.

This is achieved by using ozone in the air in the cold storage area, where it acts as an oxidizing agent and eliminates the microorganisms. The ozone also helps to remove odors and other contaminants that can affect the quality of the stored food.

Another way ozone can be used in cold storage is by injecting it into the packaging of the food products. This helps to keep the products fresh for longer by preventing the growth of microorganisms within the packaging. The ozone also acts as a sanitizer, killing any bacteria that may be present on the food surface.

It’s important to note that ozone can only be used in cold storage in concentrations that are safe for food products and the environment. The use of ozone in cold storage must be in accordance with industry standards and regulations.

Opportunities for the Future

As consumers become increasingly concerned with the environmental impact of food production, the interest in ozone as a processing technology is expected to grow. A recent study evaluated the potential of ozone in the food industry and found that it has significant potential for use in the processing of fresh produce, seafood, and beverages. In addition, ozone could play a role in reducing pesticide residues, such as organophosphates and organochlorinated compounds, on food products. The versatility of ozone also makes it a promising technology to be used in combination with other food safety measures, improving the safety and shelf life of food and beverages.

Learn more about ozone in food processing and the equipment used HERE