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From: Food Quality & Safety magazine, February/March 2014

The Natural Power of Ozone

by James Brandt

The Natural Power of Ozone

Whether ozone is assuring a pure and safe product for water bottlers or enhancing quality for seafood processors and distributors, ozone is being recognized as a valuable tool in improving product quality and safety. Ozone’s increased usage for improving food plant sanitation has evolved over the past decade following the FDA’s announcement in 2001 of approval “for the safe use of ozone in gaseous and aqueous phases as an antimicrobial agent on food, including meat and poultry.” Many of our nation’s largest companies are now using ozone to fight Salmonella and Campylobacter in poultry, botrytis in fruit, and Listeria in many foods including seafood.

What is Ozone?

Ozone is a gas composed of three oxygen atoms. The oxygen molecule in the air we breathe consists of two oxygen atoms firmly bound together. When oxygen is subjected to high voltage discharge, some of the oxygen molecules disassociate and the freed oxygen atoms then combine with existing oxygen molecules to form ozone. The third oxygen atom in the ozone molecule is loosely bound to the other two atoms and turns ozone into a very strong oxidizing agent. In many respects, ozone can be considered a more powerful green alternative to chlorine.

Ozone and chlorine differ, however, in many ways. Ozone is much stronger and acts more quickly, meaning the contact time necessary to sanitize is lessened. Chlorine is generally used at concentrations of 100 to 200 parts per million (ppm) while aqueous ozone is used at 2 to 3 ppm and gaseous ozone at 0.05 to 0.1 ppm. Chlorine leaves a detectable chemical residue on the product and is prohibited on imports into many countries. Ozone leaves no chemical residue and permits organic certification. It simply reverts to pure clean oxygen.

Why Ozone?

Ozone has the unique ability to sanitize while leaving no chemical residue. It is an aggressive sanitizing agent that when applied to a product causes no organoleptic alteration and permits organic labeling. This makes it possible to use ozone for continuous cleaning—in other words, to clean and sanitize both product and direct product contact surfaces continually during production.

The full value of ozone is industry specific but there are a number of benefits for all food processors. All processors struggle with product cross contamination and all have chronic bacterial and fungal reservoirs lurking within their plants. By incorporating a continual cleaning solution these concerns are lessened.

Continuous aqueous ozone sprays keep conveyors and other direct contact surfaces sanitized during production. These sprays produce some runoff onto floors and into floor drains, well known reservoirs of contamination, helping them to remain clean. Gaseous ozone can be incorporated into the continuous cleaning protocol by using low levels of ozone in worker occupied areas and higher levels in unoccupied areas such as freezers and storage facilities and during plant shutdowns.

The capacity to be able to slow down the progressive contamination of a plant as processing proceeds is extremely useful. It provides assurance that the product produced at the end of the day matches the quality of the product produced at the beginning of the day. It lessens the likelihood that a contaminated product will contaminate everything behind it.

Cleaning with Ozone

The cleaning power of ozone is visually grasped in several examples. The processing of ripe peaches in the San Joaquin Valley in California spans a relatively short period of eight to 10 weeks. The facilities are not air conditioned and Valley temperatures in July and August are quite warm making the peach residue on conveyors, pitters, and other contact surfaces very conducive to the growth of mold. Add to that the high sugar content of ripe peaches and the stage is set for a substantial problem. Several years ago, a trial of continuous aqueous ozone sprays on the peach conveyors was performed. A side-by-side comparison of one belt with ozone and the other without led to the worldwide adoption of ozone in stone fruit processing.

Another example of ozone’s cleaning ability was proven effective on a very soiled floor drain. After an ozone system was installed in the plant, a very low flow line serving a dissolved ozone sensor was secured with zip ties to an existing drain line. Several months later, the area of the drain receiving the small ozone stream was visibly clean.

The first example shows the ability of ozone to keep a surface clean. The second shows ozone’s ability to clean a dirty surface. Ozone is most effective if used continually. This stems from the fact that at 2 to 3 ppm it can easily be overwhelmed by heavy biological oxygen demand (BOD) loads. Low flow of continuous ozone sprays or low ambient levels of gaseous ozone are the most effective way to maintain clean surfaces and prevent biofilm formation. The ozone sprays are started minutes before production to coat the surfaces with ozonated water keeping them sanitized during the production day. This preemptive approach to cleaning virtually eliminates biofilm formation and, when coupled with interventional cleaning, can lengthen the interval for full plant sanitation.

When properly applied the addition of an ozone continuous cleaning program will enhance plant sanitation. It is not a replacement for an existing good sanitation program but rather a complement to that program. In the process, it can reduce sanitation costs in both labor time and chemicals.

The Natural Power of Ozone
This side-by-side image of ozone versus no ozone in peach processing shows how when ozone is applied, hoses, belts, and other equipment stay cleaner—reducing the down time for sanitation.

Ozone in Seafood Processing

I mentioned earlier that many of the benefits of using ozone are industry specific. These benefits are not just theoretical but can be very quantifiable. Looking at a specific industry such as seafood, we find extensive adoption of ozone technology. Whole fish are initially sprayed with ozonated water on arrival at the plant. After the fish are headed and gutted, the insides of the fish are sprayed with ozonated water as are the knives, conveyors, deboners, fillet machines, and other direct contact surfaces. As the fish travel down the processing line, they pass under spray bars which provide an additional application of aqueous ozone. Augmenting that protocol is the interventional use of ozone on indirect surfaces during break times and shift changes.

What does this accomplish? For starters, it has been shown to lengthen shelf life and improve product safety. It should be noted that the degree of shelf life extension is dependent on the point of initiation of ozone processing. Processors will typically see a two to four day extension while distributors may see a one to two day extension. The result of this is that customer charge backs, a significant cost to seafood distributors, are dramatically reduced—producing significant additions to the bottom line.

Aquaculture operations also benefit from ozone. Onshore facilities use ozone to improve colloid flocculation, nitrite oxidation as well as to put more oxygen (the ozone by-product) into the water. In clear water aquaculture, the goal is to achieve a 95 percent reduction of pathogenic waterborne bacteria in water treatment systems. These benefits all contribute to better survival and faster growth. Hatchery operations are similarly enhanced with the use of ozone.

Ozone’s Role in Food Safety

From a food safety prospective, pathogenic bacteria get and deserve the biggest headlines. All bacteria are inactivated by ozone. But remember, ozone is a topical agent and is only lethal to what it can see. Most of the organisms we are concerned about are aerobic and therefore on exterior surfaces. But one bad actor is not—Listeria monocytogenes is a facultative anaerobe and it grows well in cooler environments as well as internally in protein products. The continuous cleaning capability of ozone provides the best defense against this serious food safety problem. Ready-to-eat (RTE) products are particularly susceptible to Listeria contamination and ozone’s unique organoleptic property of leaving no residue has made it become a effective agent in many areas of RTE sanitation.

 

The degree of shelf life extension is dependent on the point of initiation of ozone processing.

Ozone Systems

Systems vary in size to accommodate large processing plants as well as smaller distributor applications. Ozone systems can be likened to sophisticated HVAC systems in that they are quite reliable but do require some regular maintenance. Usually that maintenance capacity is not available “in house,” which has necessitated OEMs developing nationwide service capabilities. Sometimes that work is subcontracted to local firms such as refrigeration companies, while larger OEMs are vertically integrated and have their own nationwide service organizations. This vertical integration, from the initial application engineering all the way through to real-time monitoring and servicing of an installed system, provides the customer the best assurance of reliable system performance.

Reliability is very important to consider as plants become dependent on ozone. A nonworking ozone system can under some circumstances cause a complete plant shutdown, such as in water bottling facilities. Service and parts need to be readily available. This is best assured by knowing that the ozone system is being monitored 24/7 and comes with an assurance of quick service availability, both now and in the future. Be aware that many parts in an ozone system are specific to that OEM’s system and not readily obtained from other vendors.

Summing Up

As ozone’s use has grown into so many areas of food processing, its future applications seem limited only by the imagination of “outside the box” thinkers. Unfortunately, some of these applications become proprietary and are not readily disseminated. The good news is that there are a multitude of applications for which ozone has become a pivotal agent in improving our nation’s food quality.


Dr. Brandt, a founder and chairman of Ozone International, is a retired surgeon with previous work in microbiological research, subclinical infections, and operating room disinfection. He can be reached at jim@o3international.com.

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