The porosity of plant cell wall regulates the cellular exchange and the diffusion of macromolecules such as enzymes during plant life. To better understand the enzyme action in the remodelling process in planta, one of the possible approaches consists in using a model system mimicking cell wall network. For this, pectin gels or pectin/cellulose binary systems were cast in cylindrical mould. To investigate the porosity of these assemblies, pullulan was chosen as a molecular probe. The diffusion of the pullulan was followed in the gels on the top of which the pullulan is deposited. The cyclinders were sliced and pullulan present in each slice was degraded by a pullulanase. Progress of the pullulan inside the gel was quantified by measurement of maltotriose concentration. The total amount of pullulan deposited on the top of gel was found under maltotriose form after diffusion in the gel and degradation by pullulanase, indicating that the developed method was relevant to quantify the pullulan mobility in the gel. With this method, we investigated the diffusion of pullulans with various gyration radia, and we varied the cellulose concentrations in order to diagnose the role of polysaccharide concentration on matrix porosity. This gave new insights on the role of the two polysaccharides in the porosity establishment. The authors acknowledge support of the FP7 RegPot project FCUB ERA GA No. 256716. The EC does not share responsibility for the content of the article.