Submitted to: Journal of Food Processing and Preservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 11, 2010
Publication Date: October 11, 2011
Citation: Geveke, D.J., Boyd, G., Zhang, H.Q. 2011. UV penetration depth in liquid egg white and liquid whole egg. Journal of Food Processing and Preservation. 35:754-757. Interpretive Summary: The safety and quality of liquid egg products could benefit from being nonthermally pasteurized by ultraviolet light (UV); however data on the penetration depth of UV in egg is extremely limited. An experimental method was developed to determine the penetration depth of UV in liquid whole egg (LWE) and liquid egg white (LEW). The penetration depth was 0.0066 and 0.0085 cm for LWE and LEW, respectively. The results of this study indicate that thin films of 0.01 to 0.02 cm depth may be required to effectively process liquid egg products with UV. This information will aid in the design of nonthermal UV pasteurizers that may well produce egg products with better quality than those currently available using thermal pasteurization.
Technical Abstract: Knowledge of penetration depth of UV in liquid egg is crucial in designing nonthermal UV pasteurizers. An experimental method was developed to determine penetration depth of 254 nm UV in liquid whole egg (LWE) and liquid egg white (LEW). An apparatus was assembled consisting of a bank of UV bulbs at the top, a container for egg in the middle, and a UV radiometer or second container for Escherichia coli at the bottom. The UV that penetrated through the egg was measured by the radiometer. In addition, inactivation of E. coli in buffered peptone water (BPW) due to transmitted UV was determined. Penetration depth, where the intensity of the UV decreases to 37% of the value at the surface, was 0.0066 and 0.0085 cm for LWE and LEW, respectively. The population of E. coli in BPW was reduced by 2.81 and 0.53 log at LWE depths of 0.018 and 0.027 cm, respectively. For LEW, the respective reductions were 4.85 and 1.05 log. This study indicates that, in order to process liquid egg products with UV, thin films of 0.01 to 0.02 cm depth may be required.