Partial characterization of films prepared with oxidized banana starch.

摘要

Manufacturing of biodegradable films from starch is important due to pollution problems caused by the widespread use of polyethylene. Films were made with oxidized banana starch and glycerol using thermal gelatinization and casting. An evaluation was made of the colour, solubility in water, and the thermal behaviour of the films. The oxidized starches presented more whiteness than the native ones, and this same pattern was observed in the films that were made. The films presented high values of luminosity L* (93), increasing when the oxidation levels of the starch increased. The solubility in water increased when the temperature and oxidation level of the starch increased. High concentrations of hypochlorite in the oxidation caused higher depolymerization of the starch. The addition of sunflower oil to the filmogenic solution produced the lowest value of solubility (17.6%), which can be associated to the hydrophobic character of oil. The addition of glycerol in the films decreased glass transition temperature (37.7 to 24.5 degrees C), which can be explained as a plasticizing effect. The films made with the oxidized starch presented higher values of fusion temperature as the concentration of chlorine increased. Enthalpy (associated with the phenomenon of fusion) decreased (175.6 to 68.9 J/g) as the oxidation level of starch increased. Oxidized banana starch is an alternative for preparing films with potential as packing material.