Properties of Films Made from CO2-Precipitated Casein

Tensile properties, water vapor permeabilities, and water solubilities were determined for casein films plasticized with glycerol. The casein was precipitated from milk that was sparged with carbon dioxide (CO 2 ). The films were compared to those made from commercial calcium caseinate. Glycerol was added to plasticize the films. At 20% (w/w) glycerol content, CO 2 −casein films were >50% stronger than the calcium caseinate films. They were significantly stiffer than the caseinate films and were approximately as elastic. The water vapor permeabilities were ∼20% less than those of the calcium caseinate films. CO 2 −casein films were only 7% soluble in water compared to 100% solubility for the calcium caseinate films. The differences in properties of the films indicate structural dissimilarities.