Permeability of gels is set by the impulse applied on the gel

To better understand sensory perception of foods, water exudation studies on protein-based gels are of a high importance. It was aimed to study the interplay of gel coarseness and gel stiffness on water holding (WH) and water flow kinetics from the gel once force is applied onto the material. Ovalbumin heat-set gels were used as a model system, where protein volume fraction was kept constant and ionic strength was varied to obtain a range of different gel morphologies and stiffness. WH of gels was measured both as a function of time and force applied. From experimental data (i) an effective gel permeability coefficient and (ii) an effective water flux coefficient were obtained and related to gel coarseness and stiffness. Gel coarseness determined maximum amount of water removed from the gel at defined conditions, where lower (<= 0.1 mu m) and upper (>= 0.4 mu m) limiting scales for water removal were identified. Gel stiffness is the major determinant for water removal kinetics from the gel. The combination of gel coarseness and gel stiffness showed a cooperative effect on gel WH. The insights can be exploited in product development to predict and tune oral perception properties of (new) products. (C) 2015 Elsevier Ltd. All rights reserved.