HYDROETHANOLIC EXTRACTION OF CAATINGA PASSION FRUIT PEEL FLOUR: INFLUENCE OF THE METHOD ON ANTIOXIDANT ACTIVITY AND BIOACTIVE COMPOUNDS

Abstract: Caatinga passion fruit peel is rich in bioactive compounds with antioxidant potential. The extraction efficiency of these compounds varies according to the method used, making it essential to compare techniques to optimize the use of this agro-industrial residue. Thus, the aim of this study was to compare two hydroethanolic extraction methods regarding the content of phenolics, total tannins, and antioxidant capacity of Caatinga passion fruit peel flour. Regarding the methodology, two hydroethanolic extraction methods (60%) of Caatinga passion fruit peel flour were compared: thermal extraction (70 °C/1 h with stirring) according to Vuolo et al. (2020) - EHV extract, and ultrasound extraction (30 min/room temperature) adapted from Arruda et al. (2018) - EHA extract. Total phenolics, condensed and hydrolyzable tannins were determined according to Chandran and Indira (2016), and antioxidant capacity by FRAP and ORAC methods (Rufino et al., 2021). The Trolox equivalent antioxidant capacity (TEAC) was evaluated in extracts of Caatinga passion fruit peel flour based on the methodology proposed by Re et al. (1999). Data were statistically evaluated using ANOVA and Tukey's test (p < 0.05). The extraction methods influenced most of the analyzed parameters. The thermal extract (EHV) showed higher contents of total phenolics (0.207 vs. 0.160 mg EAT/g), condensed tannins (88.33 vs. 17.76 mg EAT/g), and hydrolyzable tannins (2.54 vs. 1.89 mg EAT/g) than ultrasound (EHA), due to heating and longer extraction time, which favor the solubilization of these compounds. For antioxidant activity, EHV was superior in ORAC (40.68 vs. 33.73 μM Trolox/g) and FRAP (40.68 vs. 32.62 μM Trolox/g) methods, corroborating the direct relationship with the higher contents of condensed tannins, which act as potent reducing agents and hydrogen donors. In the ABTS method, there was no significant difference between extracts (9.99 vs. 9.06 μM Trolox/g), indicating that both methods equally extract compounds capable of scavenging this radical, regardless of the technique employed. It is concluded that thermal extraction (EHV) is superior to ultrasound (EHA) for extracting phenolics, condensed/hydrolyzable tannins, and antioxidant potential by ORAC and FRAP methods, attributed to heating and longer extraction time. For the ABTS method, both extracts were equivalent, indicating that ultrasound can be a viable alternative when the target is the scavenging of this radical, with advantages of lower temperature and processing time.

Acknowledgments: CAPES (financial code: 001, grant: 88887.153982/2025-00 and FAPESP (Process number: 23/17076-1).