Ozone Applications For Food Processing

There are several points in a food processing plant where ozone can be used effectively. Many processing plants use water as part of the product washing or transporting between process steps. Ozone can effectively replace chlorine disinfectants by dissolving ozone gas in the water and controlling levels by dissolved ozone sensors or standard oxidation-reduction potential (ORP) sensors used to monitor chlorine levels. Ozone can be used to disinfect the water subsequently used in the finished product, as in the beverage industry. The FDA gave GRAS approval for bottled water in 1991 and today is used in over 95% of bottle water. Products that are processed dry can be treated with ozone l.E + 08r l.E+ 07 l.E + 06 l.E + 05 ■ l.E + 04 ■ l.E+ 03 l.E+ 02 l.E+ 01 l.E+ 00'

Chlorine dioxide baseline



Ozone/filtration reaction vessel, degasser

Figure 1. A comparison of ozone with chlorine dioxide shows ozone's disinfection capabilities with various application methods.

gas. For example, the dietary supplement ginger that has been partially dehydrated can be treated in ozone at 8% for 30 min to realize a 4-log reduction in total aerobic plate counts.


Ozone used in flume water for an onion processing line produced a 3.8-log reduction of total aerobic and coliform plate counts over chlorine dioxide. Ozone was used in the flume water between a peeler and a slicer on an onion line that processed an average of 6,000 kg/h. Figure 1 shows the comparison of chlorine dioxide and ozone with various water treatment steps. The first pair of columns represents the total aerobic and coliform plate counts with chlorine dioxide. The next three sets of columns shows ozone alone, ozone with a 100-/;m filter prior to ozone injection, and ozone with the 100-/im filter, a 450-L reaction vessel, and a centrifugal gas separator. The quantity of ozone was adjusted to maintain ozone off-gassing below 0.05 ppm at the open water tanks for personnel safety. The amount of ozone used for each of the three conditions was 550,330, and 500 g/h.

Figure 1 illustrates the effect of the organic load on the consumption of ozone. Comparison of ozone alone with ozone and filtration reduces the ozone required by over 20% for the same disinfection. To achieve the most efficient use of ozone for disinfection, filtration is required to reduce the organic load. Finally, one can also observed the benefit of increasing the contact time of the ozone with the flume water by the last pair of columns in the figure, where the plate counts were at their lowest levels. Similar results were obtained for potato processing lines where, again, ozone was used to replace chlorine dioxide. In the latter case, the organic load was from potato pulp, gratings, proteins, and starch content (as high as 15% by volume) in the process water. In both examples, ozone and filtration treatments lead to the extended reuse of the process water.

Vegetarian Food and Cooking

Vegetarian Food and Cooking

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