Contact area determination between structured surfaces and viscoelastic food materials

Adhesion caused by intermolecular interaction between two systems can only occur at the contact points between the adhesive and adhered (“adhesive active regions”). The determination of the real contact area/points between viscoelastic food materials and solid surfaces would contribute to a prediction of their adhesion behavior. Therefore, two instrumental methods were developed to identify the contact area between viscoelastic food materials and solid surfaces as a function of the surface structure (static Color Print Method) and contact time (dynamic Imprint Method). The methods were validated using a wheat dough model and five structured surfaces: a strong reduction of the contact area between wheat dough and structured surfaces was identified compared to a smooth surface (e.g. 57% decrease for the nub structure). Additionally, adhesion measurements were implemented using a previous developed CTM (Contact Time Measuring) method. Correlation analysis revealed a strong linear relationship between the contact area and surface adhesion force (Color Print Method: r = +0.93; Imprint Method: r = +0.97). The adhesion distance and adhering dough residues showed a higher dependency on the type of structure. The developed methods contribute to elucidate the adhesive behaviour between a viscoelastic system and solid surfaces and thus the construction of optimized surfaces with specific structures for the food industry.