“
“In the search for environmentally friendly materials that can be used as

food packaging, edible films made from biopolymers such as polysaccharides and proteins have emerged as an alternative. However, degradation is not the only desirable characteristic of a food packaging material, which should also meet other requirements, such as mechanical strength, flexibility, and permeability to water vapor and gases, in order to ensure food preservation. Protein films are effective lipid, oxygen, and aroma barriers at low relative humidity (RH) conditions (Bamdad, Goli, & Kadivar, 2006), but they are considered unsatisfactory barriers to water Verteporfin order vapor because of the presence of hydrophilic groups

in their molecular structure (Mokrejs et al., 2009). On the other hand, starch films exhibit good oxygen barrier properties, and moderately tensile strength, not to mention the fact that they become learn more markedly brittle at low moisture (Forsell et al., 2002 and Talja et al., 2007). The hydrophilic character of starch films makes them very sensitive to moisture, thus limiting their use as food packaging material. In order to increase the mechanical strength of protein and starch films and improve their barrier properties, some authors have developed blends of these polymers (Coughlan et al., 2004 and Jagannath et al., 2003). However, the hydrophilicity of these films remained high, so other authors have added lipid to the compositions, so as to enhance their barrier properties with respect to water Liothyronine Sodium vapor (Colla et al., 2006, García et al., 2000 and Gontard et al., 1994).

To produce such films, researchers have usually employed commercial biopolymers and lipids, which are then mixed during film processing. The results are not always favorable due to the thermodynamic incompatibility of biopolymers, which may also cause phase separation (Grinberg & Tolstoguzov, 1997). To overcome this problem, natural mixtures of starch, protein and lipids, which can be obtained in the form of flour from raw materials of plant origin such as cereals and legumes, have been employed. An important raw material for production of this flour is the amaranth grain, which has significant starch, protein and lipid contents, as confirmed in our previous studies (Tapia-Blácido et al., 2007, Tapia-Blácido et al., 2005 and Tapia-Blácido et al., 2010). The amaranth flour from the species Amaranthus caudatus has good film forming ability, thereby yielding films with excellent barrier properties with respect to water vapor, moderate solubility, and high flexibility ( Tapia-Blácido et al., 2005). These properties result from the balance between the concentration of biopolymers and lipids and their natural interaction in the flour, which prevents phase separation ( Tapia-Blácido et al., 2007).