Effects of chemical properties and physical structure on mass transfer in whey protein-based edible film systems

Edible films, by regulating transfer of moisture and oxygen in food systems, can increase food shelf-life and improve quality. Edible films can also decrease amounts of synthetic packaging materials needed to preserve and protect foods, as well as improve package recyclability by reducing the need for laminates.; Whey protein is a nutritional and highly functional protein; however, much whey is currently wasted. Therefore, considerable interest exists in finding new uses for whey proteins. This was the first study to characterize the potential of whey proteins, alone and in combination with other biopolymers, as edible films.; Chapter 1 comprehensively reviewed the potential of various proteins as edible films and coatings. Protein nature, recovery, film formation and mechanical properties were examined. Food applications were also reviewed. Chapter 2 explored milk proteins as edible films and coatings. Protein nature and recovery were examined. Film formation, water vapor permeability (WVP), oxygen permeability and tensile characteristics were reviewed and applications summarized. Methods for accurate determination of edible film water vapor, permanent gas and lipid permeability properties were comprehensively reviewed in Chapter 3. Prediction and interpretation of relative humidity effects on permeabilities were discussed. Mass transfer mechanisms were reviewed, as were solubility and diffusivity analyses. Factors affecting permeability were defined and comprehensive tables developed, comparing the water vapor and oxygen permeabilities of edible films with those of synthetic films. Chapter 4 developed an improved method for determining the WVP of hydrophilic edible films. The origin of thickness effects was explained. Film formation potential and WVPs of plasticized whey protein films and whey protein-lipid emulsion films were determined in Chapters 5 and 6, respectively. Dispersed phase particle size effects on WVP were examined in Chapter 7. Next, a novel integrated method to evaluate oxygen permeability and tensile properties was developed. The plasticizer effectiveness of sorbitol versus glycerol was compared. Finally, two patent applications were presented.; Protein edible film characteristics may eventually provide a new category for defining protein functionality. This project began to explore the relationship between the chemical properties and physical structure of whey protein films and their mass transfer characteristics.