MORPHOLOGICAL EVALUATION AND ADSORPTION ISOTHERMS IN MICROENCAPSULATED ANTHOCYANIN POWDERS USING DIFFERENT POLYSACCHARIDES

Spray drying is a widely used technique for obtaining microcapsules with bioactive compounds. The objective of this study was to evaluate the effect of different wall materials on the morphology, particle size and moisture adsorption behavior of microcapsules containing purified anthocyanins from açaí. Three wall materials were used: maltodextrin 10DE, starch modified with octenylsuccinate (Capsul®) and gum arabic, at a concentration of 30% (w/v). The solutions were mixed with the purified extract in a 3:1 (v/v) ratio, homogenized in two stages (Tecnohomo, 30 L.h⁻¹, 500 bar, 30 °C) and subjected to spray drying (Buchi B-191), with an inlet temperature of 180 ± 5 °C and an outlet of 70 ± 5 °C. Particle morphology and size were evaluated by scanning electron microscopy (SEM – TM3000, Hitachi) at different magnifications (50–1500×). For the adsorption isotherms, the powders were stored in environments with different equilibrium relative humidity (11 to 97.3%) at 25 °C, using the static gravimetric method. The BET, GAB, Oswin and Smith models were adjusted to the data, being evaluated by R² and mean absolute error. The micrographs indicated that the particles presented similar shapes, with invaginations typical of the spray drying process and good surface integrity, with no apparent cracks. The largest particles were obtained with maltodextrin (7.63 μm), followed by Capsul® (7.03 μm) and gum arabic (5.4 μm)