Sustainable Sanitation Technique for Postharvest Quality and Safety of Organic Fruits

A robust infrastructure is integral to the quality, growth and sustainability of the organic agriculture industry, including requirements for product safety. The microbial safety of fresh produce is a common concern, highlighted by recent outbreaks of Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes. This project builds on our previous research investigating the potential of ultraviolet light to sanitize organic fruit. With current BIOAg program funding, we have evaluated the efficacy of ultraviolet-C light to inactivate the Penicillium expansum, an important spoilage microbe, and food borne pathogen E. coli O157:H7on organic fruit surfaces, including cherries, strawberries, red raspberries and apples. We found that the level of microbial inactivation depends on fruit surface morphology and the type of microorganism, with pathogenic bacteria E. coli being more UV-C resistant than blue mold. Our proposed project will continue these important UV-C investigations on organic fruits to include Listeria monocytogenes. This pathogen has been tied to recent outbreaks from fresh produce (e.g., cantaloupe, fresh cut apples, celery, and sprouts), for which there is a zero tolerance by the FDA. Listeria is problematic because of its environmental prevalence. It is difficult to inactivate and grows in refrigerated conditions, making it a high-risk organism. This high priority research fills the gap in the literature and also advances the BioAg program’s mission to promote sustainable practices and enhance the quality and safety of organic produce.


Grant Information

  • Project ID: 124
  • Project Status: Complete


  • Principal Investigator(s): Sablani, S.
  • Investigator(s): Killinger, K., Rasco, B.
  • Grant Amount: $21,628
  • 2013 Progress Report (PDF)



Conference Presentations:

Adhikari, A., Sablani, S. S., Killinger, K., Syamaladevi, R. M., and Gray, P. (2014). Ultraviolet-C light inactivation of Listeria monocytogenes on organic fruits, International Association for Food Protection, Indianapolis, Indiana, August 03-06.

Peer-reviewed publications:

Syamaladevi, R. M., Adhikari, A., Lupien, S. L., Dugan, F., Bhunia, K., Dhingra, A., and Sablani, S. S. (2015) Ultraviolet-C Light Inactivation of Penicillium expansum on Fruit Surfaces, Food Control 50: 297-303

Adhikari, A., Syamaladevi, R. M., Killinger, K., and Sablani, S. S., (2013). Fruit surface morphology influence on Ultraviolet-C Light inactivation Kinetics of E. coli: O157 H7 (In preparation)

Additional Funds Leveraged

Ultraviolet light (UV-C) treatment for improving safety of red raspberries, National Processed Raspberry Council, $13,695 (Sablani, Killinger, and Ganjyal), 2014-2016


Short-Term: Both pathogenic bacteria and spoilage mold can be reduced up to 2-3 log CFU/g using UV-C light. The fruit surface morphology and properties affected efficacy of UV-C light for inactivation of E. coli and Penicillium ExpansumE. coli was found to be more UV-C resistant than P. Expansum.

Intermediate-Term: The information acquired can be used to design UV-C doses for sanitization of organic fruit surface thus increasing the microbial safety and extending the postharvest shelf-life of organic produce.

Long-Term:  The improved microbial safety and extended postharvest life of organic produce will provide economic incentives to Washington organic agriculture industry. The research findings and new methods developed by this project may also lead to more environmentally-sound food handling methods and improved consumer health and safety throughout the nation.