Decontamination of green onions and baby spinach by vaporized ethyl pyruvate

J Food Prot. 2012 Jun;75(6):1012-22. doi: 10.4315/0362-028X.JFP-12-008.


Foodborne illnesses associated with fresh produce continue to be a major concern as consumer demand for healthier and nonthermally processed food increases. The objective of this study was to evaluate vaporized ethyl pyruvate (EP; CAS 617-35-6) as a safe alternative antimicrobial agent for the decontamination of Escherichia coli O157:H7 on green onions and spinach. Baby spinach leaves and green onions were inoculated with a five-strain cocktail of E. coli O157:H7 (pGFP) by the dipping method. Samples were treated with concentrations of 0, 42, 105, and 420 mg/liter vaporized EP in a 2.6-liter enclosed container. The efficacy of EP vapors for reducing E. coli O157:H7((GFP)) populations on green onions and baby spinach at 4 and 10°C was monitored for 7 and 5 days, respectively. The lowest EP concentration (42 mg/liter) resulted in a 1.7-log reduction of E. coli O157:H7((GFP)) on green onions after 7 days at 4°C and a 1.9-log reduction after 5 days at 10°C (P < 0.05). In baby spinach, the same concentration resulted in 0.9-log and 1.4-log reductions (P < 0.05) of E. coli O157:H7((GFP)) after 7 days at 4°C and 5 days at 10°C, respectively. On green onions, the highest concentration of EP (420 mg/liter) reduced the population of E. coli O157:H7((GFP)) by >4.7 log CFU/g after 7 days at 4°C and 5 days at 10°C. The same concentration was also effective for reducing E. coli O157:H7((GFP)) populations in baby spinach by 4.3 log CFU/g after 7 days at 4°C and by >6.5 log CFU/g after 3 days at 10°C. Although the successful EP treatments minimally affected the sensory attributes of green onions, the treatments resulted in significant changes in the sensory attributes of baby spinach samples stored at 4 and 10°C. These results indicate that EP is an effective antimicrobial that could be used to enhance the safety of fresh produce depending on the sensory characteristics of the product.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Colony Count, Microbial
  • Consumer Product Safety
  • Dose-Response Relationship, Drug
  • Escherichia coli O157 / drug effects*
  • Food Contamination / prevention & control
  • Food Handling / methods*
  • Food Microbiology
  • Humans
  • Onions / microbiology*
  • Pyruvates / pharmacology*
  • Spinacia oleracea / microbiology*
  • Taste
  • Temperature
  • Time Factors


  • Anti-Bacterial Agents
  • Pyruvates
  • ethyl pyruvate