Food quality and safety are the main concerns of consumers and the principal target of the food industry processes. The concept of "food process engineering for product quality" has been arising in the last years with the aim of designing and controlling processes to produce food products with very specific properties of quality and safety, previously defined on the basis of market opportunities analysis. The final properties of food products are the result of the changes in raw material as a consequence of process conditions. In the case of colloidal or cellular foods, these changes may be observed as differences in quality factors as food composition, nutritional facts, taste and flavour, aspect, shape and size, colour, texture, etc. These changes in food properties may be explained because physical and chemical phenomena produced in line with the process progression, as structure deformations, chemical or enzymatic reactions, phase transitions. etc. The models currently used in food process engineering simplify too much both the food system description and the mechanisms and rate equations of changes. The food system is supposed to be homogeneous and continuous. In this way, thermodynamic and kinetic equations deduced for ideal gas or liquids, in conditions close to equilibrium are applied to cellular solid foods, in conditions far away from the equilibrium. It is necessary to develop advanced concepts and methodologies in food process engineering. The new models for food and processes development must incorporate information about all these aspects (thermodynamic, structural, chemist and biochemist, and even mechanics). Only in this way they would be able to calculate and predict the real changes in the whole quality of food product in line with the process progression. The SAFES methodology (systematic approach to food engineering systems) recognizes the complexity of food system and allows coordinating the information about food structure, composition, quality, thermodynamic, etc. in adequate tools to develop real food and processes models. "In a complete theory there is an element corresponding to each element of reality" [Einstein, A., Podolsky, B., & Rosen, N., (1935). Can quantum-mechanical description of physical reality be considered complete? Physical Review, 47, pp. 777-780]. (C) 2007 Elsevier Ltd. All rights reserved.