INFLUENCE OF EXTRACTION PARAMETERS ON THE RECOVERY OF PHENOLIC COMPOUNDS FROM ARRABIDAEA CHICA BY SEQUENTIAL ULTRASOUND-ASSISTED AND PRESSURIZED LIQUID EXTRACTION

Arrabidaea chica Verlot, popularly known as crajiru, is a promising source of bioactive compounds—particularly 3-deoxyanthocyanidins—that exhibit remarkable chemical stability and antioxidant activity. This study aimed to extract bioactive compounds from A. chica leaves using a pretreatment involving ultrasound-assisted extraction (UAE) followed by pressurized liquid extraction (PLE). Dried leaves (particle size of 1.41 mm) underwent UAE pretreatment (40 °C, 10 min, and 50% ultrasound power) prior to PLE. An experimental design was employed to investigate the effects of extraction temperature (60–100 °C), extraction time (10–30 min), and solid-to-solvent ratio (1:4–1:12 g/mL), using 70% (v/v) aqueous ethanol as the extraction solvent. Extraction efficiency was evaluated based on total phenolic content (TPC) and antioxidant activity determined by FRAP, ABTS, DPPH, and ORAC assays. The optimal extraction condition was achieved at 60 °C for 10 min with a solid-to-solvent ratio of 1:4, resulting in a TPC of 115.42 mg GAE/g and an ABTS antioxidant capacity of 769.07 µmol TE/g. X-ray diffraction (XRD) analysis of the optimized extract revealed a broad amorphous halo between 15° and 25° (2θ), indicating a predominantly amorphous structure with potentially enhanced solubility. Fourier-transform infrared (FTIR) spectroscopy confirmed the preservation of characteristic phenolic functional groups, including O–H stretching (~3300 cm⁻¹) and aromatic C=C stretching (~1610 cm⁻¹), demonstrating that the extraction process maintained the structural integrity of the bioactive compounds of interest. Overall, the sequential UAE-PLE strategy proved to be an efficient and eco-friendly extraction approach for obtaining phenolic-rich extracts with high antioxidant potential from A. chica, highlighting its potential application as a natural functional ingredient in food systems.