OPTIMIZATION AND PHYSICOCHEMICAL CHARACTERIZATION OF A SPRAY-DRIED MICROENCAPSULATED Origanum vulgare L. EXTRACT

Resumen

This study employed response surface methodology to optimize the spray-drying conditions for a microencapsulated oregano extract (Origanum vulgare L.) using a maltodextrin-gum Arabic wall-material system. Feed flow rates of 0.5, 0.6, and 0.7 L h^-1 and inlet air temperatures of 130, 140, and 150 °C were evaluated. The oregano leaves were dried, ground, and extracted by maceration with 90% (v/v) ethanol at a 1:10 mass-to-solvent ratio at 60 °C for 24 h under agitation. Process yield, encapsulation efficiency, and moisture content were evaluated. The optimal conditions within the experimental domain were a feed flow rate of 0.5 L h^-1 and an inlet air temperature of 150 °C. Independent validation under these conditions resulted in a process yield of 94.97%, encapsulation efficiency of 94.06%, and moisture content of 3.15%, with relative prediction errors of 0.13, 0.60, and 0.73%, respectively. The resulting spray-dried microencapsulated oregano extract showed 92.0% solubility, a bulk density of 0.24 g mL^-1, a tapped density of 0.48 g mL^-1, a Carr index of 50%, a Hausner ratio of 2.00, an angle of repose of 31.58°, and hygroscopicity of 21.49 g 100 g^-1. Its ferric reducing antioxidant power was 402 µmol Fe²⁺/g sample, and its total polyphenol content was 0.15 mg g^-1. Overall, the optimized process produced a spray-dried microencapsulated oregano extract with high process yield and encapsulation efficiency and measurable antioxidant-related activity, supporting its further evaluation as a functional food ingredient.

Keywords: microencapsulation; oregano extract; spray drying; antioxidant capacity.