Food as porous media: a review of the dynamics of porous properties during processing

The complexity of food materials can be attributed to their hygroscopic, amorphous, heterogeneous, and porous structure. During processing, the microstructure of food materials changes; this significantly affects the structural and transport properties of food. A comprehensive understanding of the microstructure and its dynamics during food processing is critical to optimizing food processes and making food quality more predictable and controllable. This review critically assesses the product and process parameters that influence the modification of microstructure in the course of food processes such as pre-treatment, cooking, convective drying, freeze-drying, microwave heating, deep-frying, and baking. An extensive review of the literature indicates that food quality significantly and interchangeably depends on 1) the transport and structural properties of raw material, 2) the evolution of properties, and 3) processing parameters. A porous media framework allows a broader (and deeper) understanding of food microstructure evolution during its processing across many processes and products. This should help speed-up process optimization and novel and hybrid process development.