Ozone vs. Chlorine in the Food Processing Industry

Food Safety

Aqueous Ozone in Food Processing

Ozone food applications are widely used in food processing as a complementary or main disinfection system. They generate great outcomes for businesses. On fresh strawberry and shredded lettuce, the food quality was tested by varying applied ozone concentrations, contact times, pH and temperatures to assess ozone as a potential food sanitizer. The product quality was assessed by comparing the changes in texture, firmness, browning and decolourization, oxygen consumption and carbon dioxide respiration after the post-treatment storage from 0 to 21 days. 

The effectiveness of ozonation on natural microflora including mesophiles, psychotropics, yeasts and moulds, was also evaluated for the improvement in produce shelf-life. As compared to chlorine treatments, ozone treatments slightly increased the lettuce browning but substantially retarded its respiration rates and firmness deterioration even after 21 days of storage. For strawberry, no significant difference in food quality was observed between ozone and chlorine treatments. Finally, ozone treatments at the doses below 10 mg/L were found not effective in killing natural microflora grown on the product surfaces.

ozone food


There are concerns about food quality and microbial safety for fresh agriculture, especially minimally processed products which have minimal cleaning and sanitization before being consumed. Produce quality can be decreased due to mechanical damage from its handling and processing from the time it is grown until it is purchased by the end-user.

Testing / Method

A test was performed using chlorine and ozone on both lettuce and strawberries to determine their effectiveness in maintaining their quality and natural biological characteristics. By increasing the quality and extending the natural characteristics a better product is available for the market.

Conclusion / Results

Ozone slowed the respiration rates of lettuce, which can result in extended shelf-life. Both chlorine and ozone did not impact the respiration rate of strawberries, demonstrating that results are produce-specific. Ozone was more effective than chlorine in extending the firmness of strawberries and lettuce. Ozone was not shown to be effective in preventing browning of lettuce compared to chlorine and with strawberries, there was no change in colour.

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Authors: Wei, Kuangji, Zhou, Hongde, Zhou, Ting and Gong, University of Guelph, Guelph, Ontario, Canada

Published: Ozone: Science & Engineering, 29:2, 113 – 120