Ozone Applications in Food Processing and Professional Kitchens
Ozone, a gas that is a triatomic form of oxygen, has been used for years in applications such as the treatment of municipal water and bottled water. In fact, it has been used as a disinfectant in drinking water since 1893, as a food preservative for the cold storage of meats since 1909, and was found to prevent the growth of yeast and mold during the storage of fruits in 1939.
Ozone has enjoyed a long history of use and is known as a broad-spectrum biocide against viruses, bacteria, biofilms, fungi and protozoa— none of which can build up a resistive tolerance to ozone, because ozone disinfects by oxidation processes. Ozone does not act as a systemic poison to microorganisms, but rather, destroys them by oxidation. Consequently, it is impossible for a microorganism to build up any resistance to oxidation.
In post Covid world ozone technology is going to be an effective point of intervention in the food and beverage industry.
Ozone gas is generally created on-site by a generator via an electrical charge or from oxygen using the same process. The gas is pumped into water, and the ozonated water is used as a rinse, mist, spray or bath. The ozone survives for only a matter of minutes before decomposing into ordinary oxygen.
As an environmentally friendly disinfectant, ozone now is an alternative to chlorine and other chemical sanitizers in many segments of the food industry. Ozone-enriched water kills microbes as effectively as chlorine and is 50 percent more powerful and to act 3,000 times faster than chlorine at 100 times the strength., and since it is generated on-site its use eliminates the need for personnel to handle, mix and dispose of harsh chemicals for sanitation. Further, since ozone readily reverts to oxygen, an end-product that leaves no residue on contact surfaces.
Ozone-enriched water can be sprayed directly on floors, drains, walls, wet table equipment, tanks (externally and internally), and clean rooms via mobile or centralized systems with hand-held or drop-down, low-pressure sprayers. Over time, the use of ozonated water for sanitation in food plants removes and/or prevents biofilm. In addition, resulting runoff water is extremely clean and, over time, will improve overall plant sanitation by reducing overall microbial load.
In response to a Food Additive Petition submitted during August 2000, the U.S. Food and Drug Administration (FDA) formally approved the use of ozone as an Antimicrobial Agent for the Treatment, Storage and Processing of Foods in Gas and Aqueous Phases. The approval was published on June 26, 2001. On Dec. 21, 2001, the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA/FSIS) approved the use of ozone in contact with meats and poultry, from raw product up to fresh cooked and products just prior to packaging. In addition to direct contact disinfection of foods, ozone also can be applied to food processing equipment and non-food contact surfaces as part of a food company’s sanitation efforts.
Food Industry Applications And Evaluation Of OZONE
Ozone may be used safely in the treatment, storage and processing of foods, including meat and poultry in accordance with the following prescribed conditions: The additive is used as an antimicrobial agent in the gaseous or aqueous phase in accordance with current industry standards of good manufacturing practice. By “good manufacturing practice” in relation to ozone treatment, the FDA means the exposure of foods to sufficient ozone (concentrations and times of exposure) sufficient to accomplish its intended purpose(s). In general, but certainly when using ozone, this is not a case of “if a lit- tie bit of ozone provides ‘X’ amount of benefit, then a lot more ozone will provide a lot more benefit.”
With respect to the use of ozone in the direct contact disinfection of food, there have been many studies conducted that show benefits ranging from microbial load reduction to increased shelf life of many different types of food products. For example, Strickland Produce Co. utilizes an ozone and filtration system for processing its fresh- cut salads, and has reported that the system provides the company with a greater assurance of food safety, improves shelf life, and substantially reduces the plant’s water usage. Results from the North Coast Seafood Co. ozone system for fish processing indicate about a 50% increase in the shelf life of white fish. Similarly, two air treatment units that combine ozone and ultraviolet (UV) bulbs installed by Kraft Foods for the control of mold in the vestibule of the packaging room, have yielded better than an 80% reduction in mold.
In 1999, in one of the very first studies on the use of ozone as a sanitizer for food processing equipment, Hampson showed that microbial load could be reduced by spraying ozonated water on the surfaces. The location of this early test was the fruit and vegetable pilot plant at the California Polytechnic State University (San Luis Obispo, CA) Food Science and Nutrition Department. The ozone system used in the study was able to deliver an applied ozone dose of 2.0 ppm through a 10 gpm hand-held spray wand, typically delivering a residual (measurable) dose of around 1.5 ppm ozone-in- water solution. Environmental ozone monitoring was performed using an ambient monitor, and concentrations in solution were verified using a dissolved ozone monitor.
Various surfaces in the facility were sprayed with the ozonated water in a back-and-forth fashion for one minute. The test surfaces included a polished, stainless-steel mixing kettle and tabletop, a stainless steel shroud, a central floor drain, a plastic shipping container, and two locations on the non-slip epoxy-coated concrete floor of the facility. Test areas were not cleaned prior to sanitation, so only the effect of the ozone spray wash was measured. Testing was repeated four times, and the microbial load of a 100 cm2 area was measured before and after ozone application, using both aerobic plate count and bioluminescence (Table 1).
The results indicate that ozone applied as a spray wash is effective in reducing microbial load in the processing environment. The drain presented problems during the test because the ozonated water applied to the drain washed throughout the long central drain ditch, making results inconclusive. A second test on the drain for two minutes of exposure did provide a reduction in microbial load.
One advantage of ozone is its ability to readily oxidize microbes in solution such that once a surface is spray-washed, the microorganisms physically lifted from the surface will be killed as they find their way to a drain. The Hampson study data represents one series of tests over a two-week period, with evaluations performed approximately every third day.
With continued or daily use, this initial focus study of the application of ozone technology to surface sanitation showed that it was reasonable to expect that the microbial load would be significantly eliminated at all locations exposed to the ozone. In 2002, new data resulting from a stringent certification process is showing that the efficacy of ozone technology as it is applied to sanitation purposes has dramatically improved.
Recently, results from the first study benchmarking ozonated water against EPA standards for sanitation validate ozone’s efficacy as a sanitizer for surfaces, including processing equipment that come into contact with food. Antimicrobial efficacy and safety testing of two mobile ozone surface sanitation systems (DEL Ozone, San Luis Obispo, CA) was conducted by the Toxicology Group, LLC, a division of NSF International, according to EPA-formulated test and performance requirements.
The evaluators benchmarked these ozone sanitation systems against test and performance standards for both broad-spectrum and hospital/medical environment efficacy claims, and carried out witness testing on the antimicrobial performance of ozone as measured by the AOAC International Official Method 961.02, Germicidal Spray Products as Disinfectants Test, and by the AOAC International Official Method 960.09,* Germicidal and Detergent Sanitizing Action of Disinfectants.
Conclusion
Formal regulatory approval by the FDA (and by the USDA/FSIS) for the use of ozone as an antimicrobial agent in direct contact with foods clears away the regulatory hurdle that has impeded application of ozone to foods in the U.S., and will reassure food processing firms wishing to improve the qualities of their products by approaches involving ozone.
In addition, because ozone requires no storage or special handling or mixing considerations, it may be viewed as advantageous over other chemical sanitizers used in the food industry for sanitation purposes. Some may consider the fact that ozone leaves no sanitizing residual a disadvantage, but if a residual is desired, there are many other sanitizers available to accomplish that. Ozone can be considered a complimentary sanitizing regime to help maintain the overall cleanliness and sanitation of any food processing facility.
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