title: Effective hepatitis A virus inactivation during low-heat dehydration of contaminated green onions.
abstract: Preserving fruits and vegetables by dehydration is common; however, information is limited concerning viral survival on the produce during the process. This work demonstrated the effects of low heat dehydration on inactivating hepatitis A virus (HAV) on contaminated green onions. Inoculated and uninoculated onion samples were dehydrated at target temperatures of 45-65 °C for 20 h. HAV from artificially contaminated onions (fresh or dehydrated) was eluted by shaking at 145 rpm at 20 °C for 20 min with 3% beef extract, pH 8, and followed by 0.2 μM-membrane filtration before plaque assay and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. Dilutions of the filtrates were made for obtaining countable plaques on FRhK-4 cell monolayers in 6-well plates, and also for eliminating inhibitors in qRT-PCR. Average water activity of the onions after 20 h-dehydration was 0.227, regardless of temperature used (47.9 °C or 65.1 °C). Eight dehydration trials resulted in a linear relationship between HAV inactivation and dehydration temperature, with HAV log reduction = 0.1372x(°C) - 5.5572, r(2) = 0.88. Therefore, the 20 h-heating at 47.8, 55.1, and 62.4 °C reduced infectious HAV in onions by 1, 2, and 3 logs respectively, the Z value being 7.3 °C. It was concluded that low heat dehydration using 62.5 °C or above could effectively inactivate HAV on contaminated onions by >3 logs.
authors.affiliation: US Food and Drug Administration, National Center for Food Safety and Technology, 6502 S Archer Road, Summit-Argo, IL 60501, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Laird
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Karl F
authors.initials: KF
authors.lastname: Reineke
authors.forename: Y Carol
authors.initials: YC
authors.lastname: Shieh
mesh_terms: D003681:Dehydration; D005506:Food Contamination / Q000032:analysis*; D005519:Food Preservation / Q000379:methods*; D030041:Hepatitis A virus / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D006358:Hot Temperature; D019697:Onions / Q000821:virology*; D038301:Virus Inactivation