Effective hepatitis A virus inactivation during low-heat dehydration of contaminated green onions

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 degrees C for 20 h. HAV from artificially contaminated onions (fresh or dehydrated) was eluted by shaking at 145 rpm at 20 degrees C for 20 min with 3% beef extract, pH 8, and followed by 0.2 mu M-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 degrees C or 651 degrees C). Eight dehydration trials resulted in a linear relationship between HAV inactivation and dehydration temperature, with HAV log reduction = 0.1372x(degrees C) -5.5572, r(2) = 0.88. Therefore, the 20 h-heating at 47.8, 55.1, and 62.4 degrees C reduced infectious HAV in onions by 1, 2, and 3 logs respectively, the Z value being 7.3 degrees C. It was concluded that low heat dehydration using 62.5 degrees C or above could effectively inactivate HAV on contaminated onions by >3 logs. Published by Elsevier Ltd.