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United States Department of Agriculture

Agricultural Research Service

Title: Structure, Properties and Applications of Edible Films and Coatings from Dairy Proteins

Authors
item Dangaran, Kirsten
item Qi, Phoebe
item Tomasula, Peggy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 15, 2006
Publication Date: April 1, 2006
Citation: Dangaran, K.L., Qi, P.X., Tomasula, P.M. 2006. Structure, properties and applications of edible films and coatings from dairy proteins. 2006 Ann AOCS Mtg & Expo. St. Louis, MO. p. 108.

Technical Abstract: Based on their barrier properties, edible films from casein improve the quality of food and non-food products when applied as coatings. For example, casein coatings hinder lipid oxidation when applied to fresh meats. When applied to the surface of paperboard, casein coatings improve moisture barrier properties. Casein precipitated with high pressure-CO2 (CO2CAS) has unique properties compared to commercial acid-precipitated casein. CO2CAS is less water-soluble and films made from it are less susceptible to high humidity environments; however, the films are also opaque and hazy. The appearance of CO2CAS films is important especially if applied as a food coating. To improve the appearance properties, the particle size of the CO2CAS used to make films was reduced and particle size was varied. The effect of protein particle size reduction on tensile properties, water vapor permeability (WVP) and gloss was studied using ASTM methodology. As particle size of the CO2CAS was reduced, tensile strength and modulus of the films increased while WVP decreased. Gloss of the CO2CAS films increased, but films were still hazy. Changes in film properties correlated to changes in microstructure. SEM images of the films showed closer packing of CO2CAS particles with reduced size. Decreased particle size in the CO2CAS films created more possibilities for protein-protein interactions and less free volume in the film matrix. Consequently, the tensile strength and stiffness of the films increased and WVP decreased. Increased understanding of edible film structure and function and the effect of processing on these properties will allow for better application design and development.

Last Modified: 10/26/2014
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