Alginate Films Encapsulating Lemongrass Essential Oil as Affected by Spray Calcium Application

Abstract

[EN] The necessity of producing innovative packaging systems has directed the attention of food industries towards the use of biodegradable polymers for developing new films able to protect foods and to extend their shelf-life, with lower environmental impact. In particular, edible films combining hydrophilic and hydrophobic ingredients could retard moisture loss, gas migration and ensure food integrity, reducing the necessity of using synthetic plastics. Alginate-based films obtained from emulsions of lemongrass essential oil (at 0.1% and 0.5%) in aqueous alginate solutions (1%), with Tween 80 as surfactant (0.3%), were obtained by casting and characterized as to microstructure and thermal behavior, as well as tensile, barrier and optical properties. Films were also crosslinked through spraying calcium chloride onto the film surface and the influence of oil emulsification and the crosslinking effect on the final film properties were evaluated. The film microstructure, analyzed through Field Emission Scanning Electron Microscopy (FESEM) revealed discontinuities in films containing essential oil associated with droplet flocculation and coalescence during drying, while calcium diffusion into the matrix was enhanced. The presence of essential oil reduced the film stiffness whereas calcium addition lowered the film¿s water solubility, increasing tensile strength and reducing the extensibility coherent with its crosslinking effect.