Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 7, 2009
Publication Date: September 4, 2009
Citation: Thomas, C., Swayne, D.E. 2009. Thermal inactivation of H5N2 high pathogenicity avian influenza virus in dried egg white with 7.5% moisture. Journal of Food Protection. 72(9):1997-2000. Interpretive Summary: High pathogenicity avian influenza viruses (HPAIV) spread throughout the bodies of infected chickens, causing serious and often fatal disease. Infected hens can pass the virus into eggs that they lay, and virus present in the feces can contaminate the egg shell surface. Because HPAIV can be spread by the movement of infected birds or their products (such as eggs) during trade and marketing activity, treatments that destroy the viruses before the products are exported can prevent the spread of HPAIV to new locations. One study showed that HPAIV was not easily destroyed in dried egg white during pasteurization, but the moisture content of the dried egg white made for the study was probably much lower than the 6.0-8.5% found in dried egg white products sold to consumers, and this could have allowed the HPAIV to survive longer during heat treatment. This new study shows that pasteurization methods already used by industry to destroy other disease-causing microorganisms will also inactivate HPAIV in dried egg white with 7.5% moisture, even when large amounts of HPAIV are present.
Technical Abstract: High pathogenicity avian influenza viruses (HPAIV) cause severe systemic disease with high mortality in chickens. Isolation of HPAIV from the internal contents of chicken eggs has been reported, and this is cause for concern because HPAIV can be spread by movement of poultry products during marketing and trade activity. This study presents thermal inactivation data for the HPAIV strain A/chicken/PA/1370/83 (H5N2) (PA/83) in dried egg white with a moisture content (7.5%) similar to that found in commercially available spray-dried egg white products. The 95% upper confidence limits for D-values calculated from linear regression of the survival curves at 54.4ºC, 60.0ºC, 65.5ºC, and 71.1ºC were 475.4, 192.2, 141.0, and 50.1 minutes, respectively. The line equation y=[( 0.05494)(ºC)]+5.5693 (RMSE = 0.0711) was obtained by linear regression of experimental D-values versus temperature. Conservative predictions based on the thermal inactivation data suggest that standard industry pasteurization protocols would be very effective for HPAIV inactivation in dried egg white. For example, these calculations predict that after approximately 2.6 days at 54.4ºC there is a 1:100 probability of 1 EID50/g PA/83 HPAIV remaining when the starting titer is 5 log EID50/g.