Microencapsulation of gallic acid by spray drying with aloe vera mucilage (aloe barbadensis miller) as wall material

Mucilage of Aloe vera (Aloe barbadensis Miller) is an alternative agent for microencapsulation by spray drying of labile bioactives, such as gallic acid. The microstructure of powders prepared with Aloe vera and maltodextrin (used for comparison purposes) with and without gallic acid revealed defined and undamaged particles. Aloe vera particles without gallic acid exhibited a quasi-modal distribution while the gallic acid loaded samples presented a bimodal distribution (ie., particle size of 2-3 mu m). In maltodextrin samples, the particle size presented a modal distribution (with and without gallic acid), but the mean particle size was almost ten times larger than that of Aloe vera (about 20 mu m), as reflected in the low viscosity values of these samples. Under steady-state shear flow, the reconstituted samples depicted a shear-thinning behavior (n < 1). In small-amplitude oscillatory flow the viscous component G '' dominated over the storage modulus G'. The FT-IR analysis confirmed the effectiveness of the wall material encapsulating gallic acid. Likewise, antioxidant activity results revealed that the encapsulated phenolic compound retained its antioxidant capacity and stability due to the short contact time in the spray dryer (< 5 s). Comparison of the release profiles (i.e., maximum release time and release percentage) revealed larger magnitudes in samples of Aloe vera containing gallic acid. Thus, the observed release profiles assess the suitability of encapsulation systems based on Aloe vera mucilage for potential applications in functional foods and pharmaceuticals, where maltodextrin is commonly used.