THEORETICAL APPROACH FOR THE CALCULATION OF RADIATION D 10 -VALUE R.G. MOREIRA 1,3 , N. EKPANYASKUN 1 and L.A. BRABY 2 1 Department of Biological and Agricultural Engineering 2 Department of Nuclear Engineering Texas A&M University College Station, TX 77843-2117 Accepted for Publication February 5, 2009 ABSTRACT In the design of the food irradiation process, the knowledge of the radia- tion resistance of the target organism in the specific food commodity is required. The D 10 -value, the radiation dose needed to inactivate 90% of the microbial load in the food medium, is used to relate the amount of absorbed energy to the fractional population of the viable cells. Numerous experimental studies have been performed to determine the D 10 values of several food borne microorganisms irradiated under various conditions. Nevertheless, accurate prediction of D 10 value for a radiation treatment of a food product that has not been empirically examined can not be made due to insufficient understanding of the biological response to radiation exposure. A theoretical model for the derivation of the D 10 -value has been proposed in this study to mechanistically assess the DNA damage by energetic electrons. The step-by-step Monte-Carlo simulation technique which employed the detailed histories of the ionizing particles and the radiolytic species was utilized. The impacts of the genomic sequence, the number of the genome equivalents, and the method of DNA double strand break determination were hypothetically investigated. The developed computational methodology as well as the results presented can be used as an analytical tool to evaluate the effect of ionizing radiation on the cell survival. PRACTICAL APPLICATIONS The presented methodology can be employed as an investigative tech- nique complementary to other approaches to understand the physical, chemi- cal and biological changes in food-born pathogens exposed to e-beam. 3 Corresponding author. TEL: +979-847-8794; FAX: +979-845-3931; EMAIL: rmoreira@tamu.edu Journal of Food Process Engineering 33 (2010) 314–340. All Rights Reserved. © 2010 Wiley Periodicals, Inc. DOI: 10.1111/j.1745-4530.2009.00512.x 314