Extend the shelf-life of produce while protecting worker health and safety.
Ozone gas plays an important role in the food storage industry. On-site ozone generating systems deliver low-dose concentrations of gaseous ozone into storage rooms, helping to extend the shelf life and control the ripening and decay of produce without using harmful chemicals. Ozone kills airborne and surface microorganisms, shuts down the sporulation process, and consumes ethylene produced by ripening, leaving no residue and maintaining taste, texture and smell. Growers, packers, and processors can extend product life while minimizing loss.
Fixed ozone monitors are mission critical in cool storage rooms. Too little O3 and the benefits are lost, too much and the produce can be damaged. Portable ozone monitors can be useful for spot checks and verifying fixed monitors. A monitor should always be placed close to the generator as a precaution, in case the generator needs to be shut down because of a leak.
Why Ozone Processing of foods?
On June 26, 2001, the U.S. FDA approved ozone, a gas that is a strong oxidizing agent capable of acting as a disinfectant and antimicrobial agent, for direct contact with food. Uses include the treatment of bottled water, soft drinks, process water for reuse, cooling tower water, water for washing of food processing and handling equipment. Applied in the gas phase, ozone also has found applications in odor and mold control and the storage and packaging of harvested agricultural products and processed foods. Monitoring is important for:
Preventing oxidative damage to food products
Protecting worker health & safety
Ozone for Treating Water
Food processing plant water can come from various sources including, from a municipality, river or lake. If the water has not been treated, then ozone can be of great assistance. Ozone can serve as a disinfectant as the treated water enters the food processing plant.
Ozone for Process Water Recycle & Reuse
The process water to be recycled and reused should be treated with one or more of the following treatment steps: flocculating agents (necessary to assist removal of organic contaminants and colloidal materials), sedimentation, dissolved air flotation (DAF), or filtration. A significant advantage of ozone is that it saturates the water being treated with oxygen, giving the ozone-treated water a higher optical transmittance.
Ozone for Waste Water Treatment & Disposal
Waste waters from food processing plants usually contain high levels of organic contaminants. These usually are easily biodegradable via biological waste water treatment.. Ozone is an effective, affordable method of reducing contaminant levels and aiding filtration, without using chlorine (which can lead to chlorinated organics passing into the environment.)
Ozone for Washing Foods – Whole or Cut
For this application, water must be very clean and free of organisms. Because of the oxidative properties of ozone, many organic contaminants of food wash waters are destroyed, allowing the wash water to be used for a longer period of time before disposal. Ozonated wash water for fresh cut salad mixes can later be sent for recycling. Meanwhile, ozone-washed salad mixes can be washed with chlorinated water. It is possible to reduce water use, chlorine use and plant waste water effluent volume simultaneously, resulting in significant cost savings.
Ozone for Storage of Raw Food Products
Raw food products are often stored in an atmosphere containing gaseous ozone. In these cases, it is important to know the concentrations of ozone necessary to protect the food product(s) from damage.
Foods normally are cleaned, then packaged. When packaging in air-tight sealed plastic bags, ozone treatment can be followed by carbon dioxide and/or nitrogen. Ozone disinfects surface microorganisms, then the inert gases flush away any remaining oxygen that may allow growth of detrimental organisms.
Ozone for Treating Process Room Air
If workers are not present in a food processing room (rare circumstances – such as a storage room), ozone can be applied effective to levels that exceed federal government regulations. When workers are present, room air should be treated with levels of ozone that are below federal regulations, which may be too low to accomplish their air-treatment objective. In these cases, contaminated air can be removed from the room, treated with appropriate quantities of ozone, excess ozone destroyed, and the cleaned air then returned to the processing room. Another approach is to mount ozone-generating UV lamps in the processing room ceiling. Since ozone gas is slightly heavier than air, it will fall from the ceiling UV bulbs to the floor of the processing room. Depending on the degree of odours present (ex. a garlic processing room) the odorants normally rise upwards, where they can encounter the descending ozone gas and be destroyed. At two meters above floor level, there may be no ozone at all (as measured by a wall-mounted ozone monitor pre-set at just below the appropriate OSHA level).
Another approach is to install an ozone generator in ceiling corners and have each generator fitted with a timer. During times of human occupancy, the ozone generators are turned off. When the plant closes for the night, the timers automatically turn on, and then off again an hour or so prior to human occupancy. Gaseous ozone usually dissipates within an hour. To be sure there is no ozone above federal levels when workers return; a fan can be turned on a few minutes before workers return to exhaust the last traces of ozone from the processing room. This approach is not practical for heavy odours, or odours that develop quickly during processing. This treatment also can greatly reduce the level of airborne mould in process room air.
Ozone can also be used in large rooms used to preserve stone fruit or apples harvested in summer/fall (so they can be sold during winter/spring, after summer stocks are gone and prices are higher.) In these storage rooms, negative pressures are used, along with nitrogen gas flooding, cold temperatures (35 °F) plus a slight residual of ozone for mold and mildew control.
For Plant Wash Down & Cleaning
Many ozone equipment suppliers offer specially designed portable “ozone-wash carts”, producing a pressurized water stream that contains a few parts per million of ozone dissolved in water.
This application can also be used for the washing of workers’ boots and waterproof aprons when leaving the processing room for the day or during break periods of shift changes.
Ozonated water does not adversely affect products left in conveyors and on cutting tables. These same products sprayed with chlorine- and/or peroxide-containing sanitizers would need to be discarded.
As much as 30 percent of all produce shipments are in some way adversely affected by microbial contamination before reaching the consumer. This statistic does not account for potential loss from over-ripening, as well as the fact that organic food is even more at risk because of the absence of traditional chemicals such as fungicides. The use of ozone technology, coupled with load protection monitoring, can reduce the risk of losses, enhance food safety, and ensure higher-quality arrivals by maintaining post-harvest freshness throughout long distance voyages.
Ozone is used to kill decay and disease-causing molds, yeasts, bacteria, and viruses in the air, and on surfaces, as well as to consume and regulate ethylene levels. Certified organic and approved by the USDA and the FDA, ozone acts as a powerful, residue-free disinfectant that immediately reverts back to oxygen, leaving the product’s taste, texture, and smell characteristics in their natural state. For shipping fresh produce around the globe, ozone can extend freshness, minimize decay, and reduce pathogens without the use of chemicals. Sophisticated sensing, communications, monitoring, alerting, and reporting of all of the critical variables such as T, RH, O2, CO2, O3, time, location & power can ensure the safe, fresh arrival of food and help to continuously improve the efficiency in which safe, fresh food gets delivered to the market.
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