Salmonella is also known to be more resistant to heat at lower pH levels in egg white.
Pasteurization methods for liquid egg white were developed at a time when eggs were usually stored before being broken for liquid egg products and thus the pH of the egg whites was typically approximately 9.0 at the time of processing , whereas currently eggs may be used on the same day of lay when the pH of the white is much less alkaline, normally 7.8 .
investigated the effectiveness of two commercial liquid egg white pasteurization processes and concluded that the preheat portion of both methods did not contribute to Salmonella reduction.
They also observed a greater reduction of Salmonella when egg white pH was 9.0 rather than at 8.2. developed a method of treating liquid egg products using a low temperature treatment. Packaged liquid egg products were held at 55 C for 24 h; when the products were tested no residual Salmonella was detected.
The authors did note that when this treatment was applied to already pasteurized product the Salmonella was not inactivated because it had become thermally resistant in response to the pasteurization.