Inactivation of low pathogenicity notifiable avian influenza virus and lentogenic Newcastle disease virus following pasteurization in liquid egg products

Authors: Chmielewski, Revis; Beck, Joan; Juneja, Vijay; Swayne, David

Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2013
Publication Date: 1/10/2013
Citation: Chmielewski, R.A., Beck, J.R., Juneja, V.K., Swayne, D.E. 2013. Inactivation of low pathogenicity notifiable avian influenza virus and lentogenic Newcastle disease virus following pasteurization in liquid egg products. LWT - Food Science and Technology. 52(1):27-30.

Interpretive Summary: The United States produces and exports a large amount of egg products. Although the U.S. is normally free of avian influenza (AI) and Newcastle Disease viruses (NDV), concern about contamination of egg product with these viruses has in the past resulted in restrictions on trade. Because these egg products are normally pasteurized, this study was performed to see if standard pasteurization times and temperatures would be effective at inactivating viruses in sugared, fortified, salted and plain egg product at various times and temperatures of heat processing. The USDA pasteurization standard for various egg products are based on a reduction of 5 log10 cells of Salmonella. The standard pasteurization processes were used to inactivate low pathogenicity notifiable avian influenza and lentogenic Newcastle Disease viruses and to determine if these pasteurization processes would adequately inactivate 5 log10 viruses/ml in the four egg products. The information suggests that the pasteurization process inactivated greater than 5 log10 virus/ml in the egg products. However, the pasteurization process provides better inactivation in sugared, fortified and salted egg products, compared to plain egg products, thus providing an even greater margin of safety for inactivating AI and NDV.

Technical Abstract: Sixty seven million cases of shell eggs produced per year in the U.S. are processed as liquid egg product. The U.S. also exports a large amount of egg products. Although the U.S. is normally free of avian influenza, concern about contamination of egg product with these viruses has in the past resulted in restrictions on trade. Because these liquid egg products are normally pasteurized, this study was performed to see if normal pasteurization times and temperatures would be effective at inactivating 5 log 10 Tissue culture infectious dose50/ml of low pathogenicity notifiable avian influenza (LPNAI) and lentogenic Newcastle disease (lNDV) virus in these four egg products. Survival curves were generated to determine thermal resistance (D and zD values) of LPNAI virus A/chicken/New York/13142/94 (H7N2) and lNDV AMPV/ck/US/B1/1948 artificially inoculated into sugared, fortified, salted and plain egg products at 6.3 log10 virus/ml then heat treated at various times and temperatures. The thermal inactivation rates were then used to calculate the lethality of the pasteurization process (F). The thermal inactivation rates of LPNAI for the four egg products at 56 to 63.3 degrees Celsius ranged from 0.62 to 0.13 minutes and the change in thermal resistance of the virus (zD) ranged from 1.2 degree Celsius to less than 0.1 degree Celsius. In sugared egg yolk, the reduction of the virus in the pasteurization process at 63.3 degree Celsius for 3.5 minutes was more than three times the pasteurization requirement. In fortified egg product the viral reduction was five times the pasteurization requirement. In salted egg yolk the viral reduction was twice the pasteurization requirement, and 1.2 times in plain egg yolk (38 % solid). The thermal inactivation rate of lNDV in the four egg products at 55 to 63.3 degree Celsius was from 1.6 min to 0.1 min while the change in thermal resistance of the virus (zD) were 1.6 degree Celsius to less than 0.1 degree Celsius. In sugared egg yolk, the viral reduction due to the pasteurization process at 63.3 degree Celsius for 3.5 min was more than seven times the pasteurization requirement. In fortified egg product it was more than twice the pasteurization requirement. In salted yolk and plain egg yolk the virus reductions were 1.4 and 3.5 times the pasteurization requirement, respectively. The virus reduction data in the lethality process (F) demonstrate that LPAI/NY/94 and lNDV/B1/48 would not survive the pasteurization processes in the four egg products. Usage of this data in developing egg pasteurization standards for AI and NDV infected countries should allow safe trade in liquid egg products.