Submitted to: Food and Bioprocess Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 12, 2008
Publication Date: March 7, 2008
Citation: Geveke, D.J. 2008. UV inactivation of e. coli in liquid egg white. Food and Bioprocess Technology. 1(2):201-206. Interpretive Summary: The heat pasteurization of liquid egg white is a problem because egg white is very unstable at the temperatures necessary to kill bacteria. A laboratory-scale nonthermal pasteurizer using ultraviolet light (UV) was developed and its effectiveness at destroying bacteria was tested. Egg white, containing E. coli, was processed with UV at moderate temperatures for 160 seconds. Approximately 99.995 percent of the E. coli was inactivated. The energy of the nonthermal UV treatment was slightly more than the energy of thermal treatment. Processing with UV has the potential to improve the safety and extend the shelf life of liquid egg white.
Technical Abstract: An ultraviolet light (UV) system was developed to pasteurize liquid egg white. The system consisted of low-pressure mercury bulbs surrounded by UV transparent tubing. Egg white was inoculated with Escherichia coli K12 and pumped through the UV system at a flow rate of 330 ml/min. The effects of treatment time (0 to 160 s), temperature (30 to 50 C), and egg white pH (7 to 9) on the inactivation of E. coli were investigated. The population of E. coli in egg white was reduced by 4.3 log after being exposed to UV at 50 C for 160 s. Inactivation was linearly dependent on treatment time and was adequately described using first order kinetics (r-squared of 0.94). The electrical energy of the process was calculated to be 44 J/ml. Inactivation was directly dependent on temperature and inversely dependent on pH. UV processing has the potential to improve the safety and extend the shelf life of liquid egg white.