Determination of the Thermal Diffusivity of Edible Filmst.pdfVIP

International Journal of Thermophysics, Vol. 25, No. 2, March 2004 (© 2004) Determination of the Thermal Diffusivity of Edible Films 1 S. A. Tomás,2,3 A. Cruz-Orea,2 S. Stolik,4 R. Pedroza-Islas, 5 D. L. Villagómez-Zavala, 5 and C. Gómez-Corona5 One of the most important factors in the preparation of edible films regards the choice of ingredients. Edible films are commonly prepared with single or mixed high-molecular-weight compounds like proteins and gums. In the present work, protein and gum-based edible films were prepared and their thermal diffusivity determined by photoacoustics. The films were prepared with different concen- trations of four basic ingredients: whey protein concentrate, mesquite gum, sodium alginate, and o-carrageenan. In single-component films, the highest thermal diffusivity was found in mesquite gum (1.97 × 10−7 m2 · s−1 ), followed by sodium alginate, whey protein concentrate, and o-carrageenan samples. In composed films, the highest thermal diffusivity was obtained in a ternary film made of mesquite gum, whey protein concentrate, and sodium alginate in iden- tical parts (5.20 × 10−7 m2 · s−1 ). KEY WORDS: edible films; photoacoustics; thermal diffusivity; whey proteins. 1. INTRODUCTION The development and characterization of edible films have increasingly attracted the attention of biochemists, biotechnologists, and physicists, among others, mainly due to the large variety of applications served by these polymers. Particularly, the capability of edible films to regulate 1 Paper presented at the Fifteenth Symposium on Thermophysical Proper