14A-25

H. M. Saldanha and S. K. SHARMA. Department of Food Science, Cornell University, Stocking Hall, Ithaca, NY 14853

JUSTIFICATION: Whey protein films have a great potential to be used as a special packaging material such as for encapsulating flavors and in pharmaceuticals use than other plastic films, as they are edible and have other functional properties. However, these films have the limitations due to being susceptible to microbial degradation, high water solubility, low mechanical strength, high cost of manufacturing. More research work is needed to optimize the qualities and properties of these films.

OBJECTIVE: The objective of this work was to investigate the effect of whey protein concentrations on the properties of whey protein films.

METHODS: The whey protein films were prepared from whey protein islates (protein 97.9%) using three different concentrations (5%, 7.5% and 10%) in aqueous solutions. The solutions were heated at 90^oC for 30 min for a complete denaturation of whey proteins and were then cooled down to room temperature before subjecting to vacuum (26" Hg) to remove any dissolved air. Glycerol was used as a plasticizer and the pH of the solution was maintained at 7.0. The films were dried on smooth rectangular glass plates for 24 h at room temperature. The engineering properties of the films were determined in terms of water vapor permeability, water solubility, tensile strength, melting points etc.

RESULTS: The whey protein content had no effect on the water solubility of films. However, water permeability of films decreased and the mechanical strength of the films increased with an increase in protein content. The sealing temperature of the films with a direct relationship to the melting point decreased with an increased protein content. Denaturation of the whey proteins was essential for increasing the mechanical strength, decreasing the water solubility and permeability to water vapors. A high protein content (>12.5%) and a high calcium content in whey protein isolates were the limiting factors in film formation, as the solution formed gels during heating.

SIGNIFICANCE: The properties of whey protein films can be improved by increasing the protein content up to a certain level of concentration.