Spray-drying microencapsulation of Nigella sativa extract: antioxidant activity and pH-responsive intestinal release

Nigella sativa (black cumin) is rich in polyphenols and flavonoids with strong antioxidant and therapeutic effects; however its bioactive compounds exhibit instability and low bioavailability. This study developed spray-dried microcapsules of N. sativa extract using chitosan, gum Arabic, and maltodextrin as carrier materials. The formulations were evaluated for encapsulation efficiency (EE), total phenolic content (TPC), antioxidant activity (DPPH assay), morphology (SEM), and in vitro release under simulated gastric (pH 2.2) and intestinal (pH 7.4) conditions. Chitosan-based microcapsules showed the highest EE (78.62%) and antioxidant activity (IC₅₀ 99.64 µg/mL), with SEM revealing uniform, spherical particles (3.84–4.93 µm) and smooth surfaces. The release profile studies indicated pH-dependent behavior, with greater release at pH 7.4, suggesting suitability for intestinal delivery. Kinetic modeling indicated a non-Fickian diffusion mechanism. Overall, chitosan demonstrated superior performance and stability, producing microcapsules with strong antioxidant activity and controlled release, suggesting promising applications in functional food, nutraceutical, and therapeutic formulations.