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Explore this issueFebruary/March 2014
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.
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.