Influence of semi-solid fluid's surface tension and rheological properties on the residues at packaging materials

Residues of food are unwanted in food processing and food packaging. Therefore different properties of high viscous food and their relevance to adhesion phenomena at packaging surfaces are investigated herein. The results may be utilised to reduce the amount of sticking content. In order to quantify the amount of remaining material a method of evaluation was designed using polysaccharides solutions and mixtures of highly viscous oils as model products. The surfaces tension and rheological properties were analyzed. The work of adhesion of each product-surface system was calculated from the respective contact angle data. It was found that the viscosity has a great influence on the amount of residues. For Newtonian liquids the influence is linear. For viscoelastic liquids there are other effects that cause fewer residues when the viscosity is increased. Furthermore, it seems that fewer residues remain when the dispersive part of the surface tension of the liquid is high. A side from this the work of adhesion is a good measure to predict the amount of residue.