Porous materials: Less is more

The presence of porosity in a material was first shown by Robert Hooke (1635–1703) who, in his investigations of the natural world using the newly available microscope, observed that the structure of cork was based on regular hollow units which he termed “cells”, because they reminded him of the cells of a monastery.1 Indeed, the fact that most natural structures are porous is a clear indication that porosity plays a determining role in establishing a well-defined and suitable set of properties under constrained optimization conditions, compatible with bottom-up growth.2 A similar observation can also be made for natural and processed foods, in which the presence of porosity is instrumental in tailoring important characteristics such as the geometric surface area (and therefore the dissolution rate and the intensity of flavors), the elastic modulus and toughness (with directly affects the chewing experience), the permeability (adding the possibility of homogeneously mixing fluid and solid components), and even the ratio between profit and direct cost (most of the food products comprise a high volume fraction of quite inexpensive air…).3,4