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R. G. RICE, RICE International Consulting Enterprises, 1331 Patuxent Drive, Ashton, MD 20861

When considering ozone for applications in food and agricultural areas, it is important to understand the physical and chemical properties of this unique material. It is an unstable gas at normal temperatures and pressures, is only partially soluble in water, and is the strongest disinfectant and oxidizing material currently available for contact with foods.

Because of its instability, ozone must be generated and used on-site, since it cannot be pre-manufactured and stored. Because ozone is only partially soluble in water, special gas/liquid contacting and related equipment are required to provide its maximum cost-effectiveness in a safe (for plant personnel) manner.

In water, ozone can be readily decomposed to produce the hydroxyl free radical (HO·), which is a much stronger oxidizing agent than is molecular ozone, allowing certain chemical pollutants to be oxidized to destruction that molecular ozone cannot oxidize efficiently. Yet the hydroxyl free radical has only a microsecond half-life, and thus is not as effective for controlling microorganisms as is molecular ozone.

In testing applications in which ozone comes in contact with foods, it is important to determine (a) the minimum dosage conditions below which ozone is ineffective for its intended use and (b) the maximum dosage conditions above which damage to the specific food occurs. The optimum ozonation conditions vary among different food types.

These and other fundamentals of ozone technology will be discussed.