Title: Penetration depth of UV in liquid egg white and whole egg Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 12, 2008
Publication Date: June 28, 2008
Citation: Geveke, D., Boyd, G.,Zhang, H. 2008. Penetration depth of UV in liquid egg white and whole egg [abstract]. Institute of Food Technologists Annual Meeting. p.1. Technical Abstract: Nonthermal pasteurization of apple cider using UV light is a well established commercial process. Yet, the extension of UV technology to pasteurizing liquid egg has not occurred, partially due to the limited penetration depth of UV in egg. Therefore, in designing thin film UV reactors for egg products, knowledge of the penetration depth is necessary. The objective of the present study was to develop an experimental method of determining the penetration depth of UV in liquid whole egg and egg white. An experimental apparatus was assembled that consisted of a bank of UV bulbs at the top, a quartz container for the egg products in the middle, and either a UV radiometer or a second container for E. coli at the bottom. Known thicknesses of egg products were exposed to UV for 15 s. The amount of UV that penetrated through the egg was measured by the radiometer and by determining the inactivation of E coli in a solution of buffered peptone water (BPW). The penetration depth, where the intensity of the UV penetrating through the egg decreases to 1/e (about 37%) of the original value at the surface, was 0.066 and 0.085 mm for whole egg and egg white, respectively, based on radiometry. The population of E coli in BPW was reduced by 2.81 and 0.53 log at whole egg depths of 0.18 mm and 0.27 mm, respectively. For egg white, the respective reductions were 4.85 and 1.05 log. The results of this study indicate that, in order to effectively process liquid egg products with UV, thin films of 0.1 to 0.2 mm depth may be required.