Optimization and Characterization of Tiwai (Eleutherine americana L. Merr.) Extract Encapsulation for Potential Bioavailability of Flavonoids

Tiwai (Eleutherine americana L. Merr.) is a traditional medicinal plant from Kalimantan, rich in bioactive compounds, particularly flavonoids, which exhibit strong antioxidant activity and therapeutic benefits. However, flavonoids in free form tend to be unstable, making encapsulation necessary to enhance their stability, bioavailability, and shelf life. This study optimized the encapsulation of Tiwai extract using the spray drying method, with parameters such as the ratio of Tiwai extract to maltodextrin (ET:MD), chitosan concentration, and drying inlet temperature adjusted using Response Surface Methodology (RSM) with Box-Behnken Design (BBD). The study provided detailed results, including an encapsulation efficiency (EE) of 93.24%, loading capacity (LC) of 95.76%, total flavonoid content (TFC) of 69.23 mg QE/g, and antioxidant activity (DPPH) of 60.01 µg/mL. A significant discrepancy was found between the quercetin content determined by HPLC (148.30 µg/g) and the TFC obtained using the AlCl₃ method (69.23 mg QE/g). This difference is attributed to the different principles of the two methods, as the AlCl₃ method reacts with flavonoids and other antioxidant compounds, whereas HPLC specifically identifies quercetin. FTIR analysis confirmed successful encapsulation, showing changes in the functional groups of the encapsulated product. These findings suggest that the optimized Tiwai encapsulation formula has potential applications in functional foods and pharmaceuticals.