Optical, microstructural, functional and nanomechanical properties of aloe vera gel/gellan gum edible films

Edible films of Aloe vera gel (Al), gellan gum (Ge) and their blend (AlGe) were prepared by the casting method and dried in a conventional oven. Optical, microstructural, functional and nanomechanical properties were evaluated. The films elaborated had adequate optical properties to be used in foods; AlGe showed higher values of transparency (6.5), total color difference (5.4) and extinction coefficient (0.052) than the Al and Ge; however, intermediate gloss (34.4) and refractive index (1.53) values were obtained for AlGe, maybe promoted by chemical interactions between Aloe vera and gellan gum. Microscopy and image analysis techniques were used to evaluate the microstructure of pure and blend films; the interactions due to the crosslinked among the polysaccharides of the blend were elucidated by atomic force microscopy. Water sorption capacity (-0.42 %/min) and water vapor permeability (21.3 g.mm/d.m^2.kPa) of AlGe were enhanced as compared to Al and Ge; besides the hardness (2.3 MPa) and elastic modulus (0.1 GPa) of the blend at nanometric level was reinforced with the gellan gum addition. The present research could be helpful to understand the blending Effect on the property-structure-functionality relationships of edible films with potential use in food industry.