Use of Ozone and Infrared Heating as a Pre-treatment for Drying Fruit

Tech ID: 32350 / UC Case 2020-556-0


Sequential ozone and infrared pre-treatments prior to hot air drying of fruit inactivates enzymes responsible for fruit browning, and concurrently reduces microbial contamination risk and air drying time.

Full Description

Both ozone usage and infrared (IR) heating have current applications as food drying and preservation techniques. However, each of these has trade-offs among food safety, the quality of the dried product, rehydration characteristics, and energy efficiency. For example, extended ozone exposure results in reduced enzyme activity of treated fruit - which helps preserve the fruit, but also affects physical and flavor profiles. Sulfur dioxide has also been used widely to reduce the microbial risk of treated fruit - but can leave undesirable residues on the finished fruit product that have raised human health concerns.

Researchers at the University of California, Davis have developed a technology to dry and preserve fruit that combines sequential ozone and infrared (IR) heating treatments with subsequent hot air drying. This technology reduces both microbial risk and total drying time significantly. It delivers several, desired, consumer preferences, increasing the dried products’ marketability. The drying technique saves energy while simultaneously improving the appearance of the final product, better preserving the light coloring associated with many fresh fruits. This technology achieves similar efficacy to current fruit preservation and drying processes. However, it minimizes the presence of unattractive physical end-product characteristics and eliminates undesirable residues that can result from current industrial-scale practices.


  • Fruit drying applications at industrial scale


  • Delivers microbial reduction better than that of ozone-only, sulfur dioxide, or IR-only treatments 
  • Maintains better-dried fruit quality and appearance 
  • More energy efficient than air drying alone 
  • Produces lighter color finished (dried) products 
  • Dried product can be rehydrated easily with limited loss of original fresh fruit characteristics Product meets “clean labeling” criteria

Patent Status

Patent Pending


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  • Khir, Ragab
  • Pan, Zhongli

Other Information


Food safety, Food Preservation, Fruit Drying, Ozone, Infrared Heating, IR, Microbial Reduction, Sulfur Dioxide Replacement

Categorized As

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