Influence of Temperature and Solvent Composition on the Intermittent Pressurized Liquid Extraction (PLE) of Bioactive Compounds from Baccharis dracunculifolia

Baccharis dracunculifolia (alecrim-do-campo) is na aromatic and medicinal plant native to South America, rich in phenolic compounds associated with antioxidant, anti-inflammatory, and antibacterial activities. Due to these prperties, its extracts have potential for industrial applications. However, the recovery of these compounds remains a technological challenge, since conventional extraction methods are often limited by high organic solvent consumption, long processing times, and low selectivity. In this contexto, pressurized liquid extraction (PLE) has emerged as a promising alternative, employing solvents under subcritical temperature and pressure conditions to enhance the recovery of bioactive compounds. Therefore, the present study aimed to evaluate the effect of process variables on the total reducing content (TRC) and antioxidant capacity of Baccharis dracunculifolia extracts. Alecrim-do-campo samples collected at the Lagoa do Sino Campus of the Universidade Federal de São Carlos were dried and subsequently ground. For PLE, pressure (10.34 MPa), time (5 min), and number of cycles (3) were kept constant, while temperature (60, 100, and 140°C) and solvent composition (50, 75, and 100%) were varied. The extracts were evaluated for TRC using the Folin-Ciocalteu method and for antioxidant capacity using the ORAC assay. The recovery bioactive compounds were favored by elevated temperatures and intermediate ethanol proportions, with the treatments containing 50 and 75% ethanol at 140 °C showing the highest TRC values (110.60 ± 14.72 and 111.36 ± 6,56 mg GAE g⁻¹ DB, respectively), with no significant differences between them (p > 0,05. This behavior may be related to enhanced mass transfer at higher temperatures and to the affinity of phenolics compounds for hydroethanolic solvents. The highest antioxidant capacity values were obtained in systems containing intermediate ethanol proportions (50-75%) and operated at elevated temperatures (100-140 °C), corresponding to 7.53 ± 3.50, 7.78 ± 2.30, and 7.21 ± 1.92 mg TE g⁻¹ DB, respectively, with no significant differences among them (p > 0.05). Overall, PLE demonstrated considerable potential for recovering bioactive compounds for alecrim-do-campo, particularly in systems containing intermediate ethanol proportions combined with higher temperatures.