Mechanical and Thermomechanical Properties of Films Based on Whey Proteins as Affected by Plasticizer and Crosslinking Agents

¹ Facultad de Agronomia, Universidad de la Republica, Montevideo, Urugay
² Ecole Nationale Supérieure Agronomique de Montpellier, 2 Place Viala, 34060 Montpellier, Cedex 1, France

The plasticizing effect of glycerol and the crosslinking effect of formaldehyde and calcium chloride on the mechanical and thermomechanical properties of whey protein-based films were studied. Increased plasticizer content increased the percentage of solubility in water and decreased the mechanical resistance, apparent Young modulus, and glass transition temperature of the whey protein films. The incorporation of formaldehyde as a crosslinking agent enhanced the mechanical properties and insolubility behavior and increased the glass transition temperature. The addition of a low concentration of CaCl₂ in the film formulation did not significantly effect the functional properties of the films. These changes could be partially explained by the modifications in cohesion between the protein chains because of changes in type, intensity, and distribution of the intermolecular interactions.

Key Words: whey protein • plasticizer • crosslinking agents • glass transition

Submitted on December 30, 1997
Accepted on April 28, 1998