Adhesion of edible oils to food contact surfaces

Adhesion of oils and fatty food products to packages is an important storage problem, because it increases product-package interactions that alter quality. Reducing such adhesion would also allow savings in recycling and cleaning processes. The aim of our work was to test if some thermodynamical adhesion models were correlated to edible oils' bulk adhesion as measured experimentally. Food-contact surfaces were low-density polyethylene, polyethylene teraphthalate, stainless steel, and glass. The Young-Dupre equation and five models of adhesion from the literature were used to calculate solids' surface tension and the thermodynamical work of adhesion (Wa). The dispersive, polar, acid-base, and hydrogen surface tension components of oils and solids were calculated. The experimental adhesion, or amount of edible oils remaining on solid surfaces after contact, was found to be correlated to Young-Dupre Wa, involving contact angle measured by specially designed image analysis technique. Two models, involving, respectively, surface tension's hydrogen component and a linear dependence of Wa(p) on the liquid polar surface tension component, fitted best with oil bulk adhesion as measured experimentally. Our theoretical approach to fatty food material adhesion seems, so far, consistent to predict. global residues of edible oils on solid surfaces.