Avaliação de diferentes composições de material de parede na microencapsulação de óleo essencial Lemongrass

Abstract

This work was conducted with the objective of evaluating the use of different combinations of biopolymers for the encapsulation of lemongrass essential oil by means of spray drying. The analyzed materials were: gum arabic, maltodextrin (corn – DE10 and DE20; cassava – DE10) and starch modified with octenyl succinic anhydride (OSA starch). Gum arabic is commonly used for this process, however, due to its elevated cost, its substitution for lower cost or more abundant polymers becomes commercially interesting. The emulsions were formed using ultrasound to decrease the size of the oil droplets. Both emulsions and micro-particles were investigated. The combinations of the matrix material presented the same density as the emulsion and presented no creaming formation, except in the treatment with substitution for starch modified with succinic anhydride, which presented 22.5% of creaming and density significantly lower than the others (p<0.05). The rheological behavior of the formed emulsions had a Newtonian nature for all treatments, given that the viscosity presented no significant variations with the increase of shearing. However, the viscosities presented different values for each treatment, being that the treatment with matrix constituted only of gum arabic presented greater viscosity. In terms of yield of the process and percentage of carriage, it was verified that the treatment with only gum and the treatment with substitution for starch modified with succinic anhydride obtained the best results. The substitution for DE20 corn maltodextrin presented the lower values. The solubility, moisture and thermal degradation analyses presented no significant differences for the evaluated treatments. The produced micro-particles presented greater thermal stability than the pure essential oil. To understand the behavior of water adsorption of the materials, when these are exposed to certain environmental conditions, the adsorption isotherm, kinetic and higroscopicity analyses were conduced. The GAB model was the most suitable to describe the behavior of the isotherms. Pure gum arabic presented greater water adsorptions when compared to the remaining treatments in all analyses to this end. The substitution of gum arabic for other biopolymers is a potential alternative for encapsulating lemongrass essential oil, despite the exclusive use of gum arabic presenting a few different properties from the others.