THERMAL CONDUCTIVITY MODELS FOR POROUS BAKED FOODS C. REYES 1 , S.A. BARRINGER 1,3 , R. UCHUMMAL-CHEMMINIAN 2 and G. KALETUNC 2 1 Department of Food Science and Technology The Ohio State University 2015 Fyffe Road, Columbus, OH 2 Department of Food, Agricultural and Biological Engineering The Ohio State University Columbus, OH Accepted for Publication March 1, 2006 ABSTRACT Models for the thermal conductivity of porous food were developed by modifying the parallel model to include structural data such as pore diameter, pore wall thickness and shortest path ratio. The predictions from these models and 12 literature models were compared to values determined for 12 porous foods. The models from the literature considered the air volume fraction but no other structural information. The proposed parallel, Kopelman random (KR) and Kopelman fibrous parallel models gave predictions that were not signifi- cantly different from the experimental thermal conductivity. All acceptable models except the KR model are variations of the parallel model, indicating that heat flows in parallel through the air and solid portions of porous foods. Regression analysis determined that only the thermal conductivity of the solid and shortest path ratio significantly correlate to the final thermal conductivity, indicating that the configuration of the pores is important in porous foods. INTRODUCTION Many foods are thermally processed to preserve them, such as canning, drying or freezing. These processes involve heat transfer; therefore, the heat transfer properties of foods are essential to predict rates for these processes. Thermal conductivity is needed to determine the temperature profile during a process and to select the appropriate equipment. 3 Corresponding author. TEL: (614) 688-3642; FAX: (614) 292-0218; EMAIL: barringer.11@osu.edu Journal of Food Processing and Preservation 30 (2006) 381–392. All Rights Reserved. © 2006, The Author(s) Journal compilation © 2006, Blackwell Publishing 381