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B. C. HAMPSON, Food Science and Nutrition Department, California Polytechnic State University, San Luis Obispo, CA 93407

It is imperative that food companies use sanitary water in the washdown and cleanup of their processing facilities. Ozone can sanitize process waters and, by extension, be used for facility environmental sanitation.

The physical and chemical properties of ozone facilitate its use as a food and food process facility sanitizer. Generated on demand, ozone is readily dissolved in cool water, oxidizes organic materials, including biofilm, and effectively kills all forms of microbial life. The Food and Drug Administration believes that ozone, used in combination with Good Manufacturing Practices, is an acceptable alternative to other chemical-based sanitation regimes.

Ozone was dissolved into water to create ozone-enriched water with a concentration between 1.5 and 4.0 ppm. Ambient and dissolved ozone concentrations were monitored during experimentation. Some experiments (e.g., milking equipment) required sanitation with ozonated water in a wash tank, and other experiments involved the use of a commercial spray wash unit capable of delivering a 1.5- to 2.0-ppm ozone-enriched water jet at 10 gal/min. Stainless-steel surfaces (milking equipment, steam kettle, table top, and shroud), floor surfaces (enamel; high and low traffic areas), floor drains, and plastic food shipping containers were evaluated in the study. Surfaces were swabbed before washing with both a sterile sponge (100 cm²) and a sterile swab for subsequent microbiological analyses. The surfaces were sanitized for 1 or 2 min, and an adjacent 100 cm² area re-sampled. Serial dilutions were performed in the lab on the sponge and aerobic plate counts performed. Swabs were used in an ATP-bioluminescence test. Results were expressed in APC colony-forming units or Relative Light Units (RLUs), respectively, per 100 cm². All tests were repeated a minimum of four times.

Microbial reductions ranged from 63.1 to 99.9% for a 1-min spray. No washing was performed on the surfaces prior to ozone exposure.