Adhesion to solid surfaces of gels of iota–carrageenan alone or in mixture with casein

The adhesiveness of iota–carrageenan gels was evaluated versus their rheological properties such as storage modulus and loss tangent levels and the solid surface in contact (steel or plastics). Different viscoelastic behaviours were obtained by varying iota–carrageenan concentration or temperature. Furthermore, gels were added with casein without changing their rheological properties measured in dynamic mode (small deformation), to study the influence of solid surface tension of gels on adhesiveness. After the determination of rheological parameters of gels with dynamic rheological method, the level of adhesion was measured by a pull off test. The maximum force and the energy of adhesion measured during the separation of the gel from the solid surface were studied. Both were inversely related to the storage modulus of the gel. They increase with decreasing loss tangent (corresponding to an increase of the level of structure of the gel). Moreover, the maximum force measured during separation increases with the solid surface tension (steel or plastic) and the more structured the gel, the higher is the adhesiveness differences between surfaces. .2–0.3% (w/v) of casein are added to gels with high enough storage modulus (>90 Pa), the maximum separation force increases whereas the energy of adhesion is not affected. Casein may facilitate the propagation of the rupture at the interface.