Physical Properties of Edible Gelatin Films Colored with Chlorophyllide

Abstract

Scientific interest in edible and/or biodegradable films has increased greatly in recent decades. Of the macromolecules used to produce these materials, proteins have been extensively used due to their excellent functional properties. Moreover, proteins are a raw material normally obtained from renewable sources. In particular, gelatin is one of the most highly studied proteins, since it can be produced in abundance at relatively low cost. Gelatin films are practically colorless, and thus coloring may enhance their attractiveness. The objective of this chapter is to present and discuss the physical properties (including light-barrier properties) of artificially colored edible films, with an emphasis on gelatin films with the addition of chlorophyllide as a function of pigment concentration and film thickness. The films were produced by casting a film-forming solution (FFS) made of gelatin, sorbitol (plasticizer), and chlorophyllide in an aqueous solution (10%). The effect of concentration of this pigment on moisture content, water solubility, water vapor permeability, mechanical properties, gloss, light-barrier properties, opacity, and color of films was studied. Also, the effect of thickness of the colored films on color parameters was studied more extensively. Overall, increasing the chlorophyllide concentration significantly increased the color of the films without necessarily affecting the other physical properties studied. All color parameters were strongly affected by film thickness. The use of natural pigments may be valuable for edible film technology. In choosing the pigment, one should consider not only the intended color, but also the overall effect on film properties.