Heat and mass transfer formulations appearing in the food processing literature are synthesized in a systematic and comprehensive way, under the umbrella of transport in porous media. The entire range of formulations starting from the most fundamental to the semi-empirical are covered. Relationships of different formulations to each other and to the fundamental conservation laws are shown. The important transport mechanism in foods governed by the Darcy's law is emphasized. Food processing examples of various formulations are provided. (c) 2006 Elsevier Ltd. All rights reserved.