The aim of this work is to extend the hydrodynamic mechanism (HDM) analysis, initially considered with no occurrence of deformations in the solid matrix, to the case of coupling HDM and deformation-relaxtion phenomena (DRP). The mathematical model developed in a previous paper regarding HDM, has been extended taking into account the possibility of solid matrix deformations because of the expansion and compression of the gas occluded into the porous structure. An experimental procedure has also been developed to assure the proposed mathematical model. The first experimental results affirm that HDM and DRP couple during the pressure changes in porous solid-liquid systems, and that the coupling itself has an important influence on the final values of mass transferred by HDM and permanent deformations in the solid food.