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Ozone (O3) is a reactive oxygen species; a powerful oxidizing agent
Ozone is produced when oxygen molecules are dissociated by an energy source into oxygen atoms and subsequently collide with oxygen molecules to form ozone gas. Ozone gas is much less stable than oxygen gas. Ozone has to be generated on-site because of its unstable character. It decays to oxygen following the reaction 2 O3 → 3 O2. Because ozone decomposes spontaneously into oxygen, the accumulation of organic waste in the environment is minimized. Most people can detect about 0.01 ppm of ozone in air where it has a very specific sharp odour. Hydrogen peroxide and hydroxyl are formed when ozone decomposes in water. This water has a great oxidizing capacity. Hydrogen perioxide and hydroxyl can penetrate the cell walls of bacteria, leading to disruption of the cell. The antimicrobiological effects are caused because ozone interferes with cellular respiration by direct reactions of free radical-mediated destruction. Therefore, ozone is capable of inactivation of bacteria, yeasts, protozoa and viruses. Studies show that treatment times for inactivation of bacteria vary from 0.1 to 20 min (where for the latter an inactivation of log 4.5 is achieved.
Ozone can be utilized to inactivate bacteria, yeasts, moulds, protozoa and viruses. Application areas for ozone can be:
- Disinfection of air in storage space and therefore longer shelf-life
- Disinfection of water (waste water, drinking water, cooling water, fish breed ponds)
- Break down of ethylene (C2H4 CO2 + H2)
- Break down of enzymes in wash water
- Washing and disinfection of fruits and vegetables in ozonized water less dissipation
- Re-use of wash water
- Reduction of odour problems
- Ozone therapy
- Extend shelf life of meat, fish etc.
Ozone can be used in areas like health care, food industry and water treatment plants
Ozone might have the potential to extent the storage life of fruits and vegetables. The effect on shelf-life and quality of the product depends however on the kind of fruit or vegetable. A study of Keutgen and Pawelzik 2007 shows that exposure to ozone decreases the level of vitamin C, increases lipid peroxidation and lowers sweetness in strawberries. The advantage however is that no residue is left on the product. The advantages and disadvantages per product therefore have to be investigated.
Pros and cons
- No residue left on product
- No residue in waste water
- Ozone is produced on location so no storage place needed
- Dosage of ozone is simple
- No other product needed to disinfect fruit and vegetables
- Washing water can be used multiple times because contamination is low
- Ozone itself can be harmful even in low concentrations (0.008 mg L-1). It can influence lung function and irritate the respiratory system.
- Treatment times are relatively high
- Ozone quickly loses its activity due to oxidation with other organic compounds.
- Ozone is corrosive to process equipment and irritating and possibly toxic.
Ozone is a chemical technique. Although its a novel technology, there are companies selling ozone equipment.
The costs depend on the application area. The application area of ozone is very wide and therefore no cost indication can be provided.