PROXIMATE COMPOSITION AND ULTRASOUND ASSISTED EXTRACTION OF REDUCING COMPOUNDS FROM OITI PULP AND PEEL FLOUR

Oiti (Licania tomentosa) is an underused Brazilian fruit whose nutritional composition and bioactive constituents support its investigation as a source of food ingredients (Lima de Medeiros et al., 2020). Ultrasound-assisted extraction can promote matrix disruption and mass transfer through acoustic cavitation, while solvent composition influences compound solubilization and selectivity (Medina-Torres et al., 2017). This study characterized oiti pulp-and-peel flour (OPPF) and evaluated the effects of ethanol concentration and nominal ultrasonic power on extraction yield and reducing capacity. The pulp-and-peel fraction was dried at 65 °C for approximately 20 h, ground, and stored at −18 °C. Proximate composition was determined following AOAC (2005). Ultrasound-assisted extraction was performed for 6 min at a flour-to-solvent ratio of 1:50 (w/w), using a 20 kHz sonicator equipped with a 13 mm probe. Extraction time was selected from a preliminary kinetic study showing limited additional TRC recovery beyond 6 min. Nine combinations of ethanol concentration (0, 50, and 100%, w/w) and nominal ultrasonic power (200, 500, and 800 W) were evaluated in triplicate. Global extraction yield, total reducing capacity (TRC), and ferric reducing antioxidant power (FRAP) were determined. TRC was assessed using the Folin–Ciocalteu assay (Singleton et al., 1999), and FRAP was determined according to Benzie and Strain (1996), with adaptations. Data were analyzed by ANOVA and Tukey’s test at a 5% significance level. OPPF contained 12.67 ± 0.22% residual moisture, with lipid and ash contents of 3.83% and 3.80%, respectively, on a dry matter basis. Solvent composition significantly affected all three extraction responses. Water and 50% ethanol provided higher global extraction yields than pure ethanol. The highest mean yield was observed with water at 200 W (32.36 ± 4.89%), whereas pure ethanol yielded 6.87–8.84%. The 50% ethanol mixture produced the highest TRC values (1.72–1.79 mg gallic acid equivalents/g OPPF), whereas pure ethanol produced the highest FRAP values (3.13–3.35 mg Trolox equivalents/g OPPF). These contrasting responses suggest solvent-dependent recovery of compounds contributing differently to the two assays. TRC does not exclusively quantify phenolics, and individual compounds were not identified in these extracts. Within each solvent composition, no significant differences in TRC or FRAP were detected among nominal powers. Therefore, 50% ethanol was selected as a compromise among yield, TRC, and FRAP, and 200 W as the lowest tested power, since higher powers offered no statistically detectable benefit in TRC or FRAP. This condition provided 25.82 ± 1.61% yield, 1.72 ± 0.09 mg gallic acid equivalents/g OPPF, and 2.84 ± 0.12 mg Trolox equivalents/g OPPF, supporting the valorization of oiti pulp and peel. The authors acknowledge FAPESP (2025/17032-0), CNPq (420526/2023-4), and CAPES (Finance Code 001).