Films Based on Starches

Abstract

This chapter discusses film forming ability of different native and modified starches by casting method. Likewise, rheological properties of filmogenic suspensions are described.Films mechanical and barrier properties, as well as, microstructural characterization of these biomaterials are also discussed since they determine their performance and applications, mainly in food preservation. Films characterization was carried out using different complementary techniques such as infrared spectroscopy (FTIR), light microscopy, scanning electron microscopy (SEM), Atomic Force microscopy (AFM), X-ray diffraction, Differentialscanning calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Besides, plasticizer effect (glycerol and sorbitol) on films properties was also analyzed. Even though film forming capacity of different chemically modified corn starches was evaluated, in this chapter it is only described and discussed results concerning to acetylated corn starch films. This selection was relied on the lowest water vapor permeability of films based on this modified derivative.Addition of specific additives to formulation modifies films functionality transforming them in active films. Thus, in this chapter results concerning to starch films with potassium sorbate are presented. Furthermore, antimicrobial agent diffusion from starch matrices is also discussed in order to demonstrate the effectiveness of these active films.With the purpose to develop biodegradable packages, heat sealing capacity of native and acetylated corn starch based films was studied. Film composition effect and presence of plasticizer on the type of heat sealing failure and its resistance is also discussed.Thermoplastic starch (TPS) is a biodegradable material which can easily be adapted to different processes employing standard equipment used for synthetic polymers, such as extrusion, blowing, injection and compression molding. Thus, development of biodegradable films from TPS by extrusion and blowing methods is discussed. The relevance of this study lies essentially in the demonstration of the possibility to develop biodegradable films based on TPS employing industrial methods.