Physicochemical and microstructural characterization of films prepared by thermal and cold gelatinization from non-conventional sources of starches

Abstract

Edible films were developed using different starch sources (banana, okenia and mango). Starch suspensions were cold gelatinized with NaOH or gelatinized by heat. Glycerol was used as plasticizer. Films were characterized by X-ray diffraction, Scanning Electron Microscopy (SEM), water vapor permeability and mechanical analyses. Films prepared with thermal gelatinization showed homogeneous surfaces without pores or cracks compared with starch films made with cold gelatinization, and additionally, thermal gelatinization produced films that during storage, recrystalized as a B-type compared with the A-type X-ray diffraction pattern of the films elaborated with cold gelatinization. These differences had an important role in the thickness, barrier and mechanical properties. In general, films prepared with the thermal gelatinization method, showed better barrier and mechanical properties, important characteristics when choosing the preparation method of the films. In some parameters studied, the starch source had an important role in the properties of the films. Non-conventional sources can be used for film preparation with certain barrier and mechanical characteristics.