Reduction of Escherichia coli O157:H7, Listeria monocytogenes, or Salmonella on Whole Yellow Onions (Allium cepa) Exposed to Hot Water

What is it about?

Home and food service methods to reduce microorganisms on the surface of fresh produce are limited. Hot water treatments are an option for some types of produce but data for onions are lacking. The reduction of inoculated pathogenic bacteria on whole onions exposed to hot water was investigated. Pathogens were inoculated on the stem, equator, and root end of the onions. Water temperatures of ≥85°C for ≥60 s resulted in significant reductions of pathogens, with minimal visual damage to the onion flesh. Bacteria inoculated at the root end were the most challenging to eliminate, but the treatment was effective when the root end was completely submerged or when the water bath was covered. A short hot water treatment is a simple and effective way to reduce microorganisms on the surface of whole onions.

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