María José Fabra

Edible and Biodegradable Starch Films: A Review

Mainly due to environmental aims, petroleum-based plastics are being replaced by natural polymers. In the last decades, starch has been evaluated in its film-forming ability for applications in the food packaging area. Characteristics of the starch film matrices, the film formation methods, and physicochemical properties of the starch films are reviewed in this paper. The influences of different components added in casting methods and thermoplastic processes have been also analyzed. Comparison of mechanical properties of newly prepared starch films and stored films reveals that the recrystallization phenomenon made the films more rigid and less stretchable. These effects can be inhibited by adding other polymers to the starch matrix. Other approaches to improve the starch films’ properties are the reinforcement by adding organic or inorganic fillers to the starch matrix as well as the addition of functional compounds. In this way starch films have improved mechanical and barrier properties and can act as a bioactive packaging. Physicochemical properties of the starch films showed a great variability depending on the compounds added to the matrix and the processing method. Nevertheless, dry methods are more recommendable for film manufacturing because of the greater feasibility of the industrial process. In this sense, a better understanding of the nano and microstructural changes occurring in the matrices and their impact on the film properties is required.

Effect of Different Components of Edible/Biodegradable Composite Films on Water Relationships in the Polymer Matrix

Films and coatings based on edible/biodegradable hydrocolloids have received special attention in the last few years as an alternative to preserve foods with several possibilities: to maintain sensory and nutritional properties or microbial stability, to reduce moisture losses or mechanical damage, to improve food appearance (especially gloss), to add different food ingredients such as color or aroma compounds, to incorporate bioactive compounds such as antimicrobials or antioxidants, and to reduce the use of plastic packaging. Films or coatings must be transparent, flavorless, and odorless and they must have adequate water vapor permeability and selective permeability to gases and volatiles. They must not represent a health risk and be low cost (Krochta and de Mulder-Johnston 1997; Tharanathan 2003).