BIO-GUIDED EXTRACTION OF PHENOLIC COMPOUNDS FROM DEPECTINATED ORANGE POMACE FOR PRODUCTION OF FUNCTIONAL INGREDIENT: A COMPARATIVE STUDY OF HYDROETHANOLIC AND ULTRASOUND-ASSISTED EXTRACTION

Depectinated orange pomace (DOP) is an undervalued byproduct of the juice and pectin industries that remains rich in phenolic compounds. This study aims to optimize the recovery of bioactive phenolics from depectinated orange pomace using green extraction technologies. By comparing conventional hydroethanolic extraction (CHE) with ultrasound-assisted hydroethanolic extraction (UAHE), this research seeks to maximize antioxidant potential and specific flavonoid yields. Two wet DOP samples, differing by cultivar composition, DOP-1 (Valencia variety) and DOP-2 (a blend of Valencia, Natal, and Pera varieties), were subjected to industrial wet-milling (Comitrol mill) and Rotary Drum drying (140 °C, 2–4 rpm). The effects of pre-treatments and cultivar composition on total phenolic content (TPC) and antioxidant activity by ORAC were evaluated using CHE. Also, to optimize CHE parameters, it was evaluated the solid-to-solvent (ethanol 50%) ratios and agitation methods (Ultra-Turrax, orbital shaker, and their combination). Subsequently, UAHE was optimized using a Central Composite Rotational Design (CCRD) varying ultrasound amplitude and extraction time. Results showed that cultivar composition had a greater impact on TPC and ORAC than the drying process (p<0,0001), with dried DOP-2 exhibiting superior values for both responses. No significant differences in TPC or ORAC were observed among the agitation methods; thus, the Ultra-Turrax method with a 1:25 ratio was selected, corresponding to a TPC of 38.46 ± 1.35 mg EAG/g of dry extract (DE), ORAC value of 2386.41 ± 130.10 mmol TE/g DE and, extraction yield of 4.4 ± 0.1%, coupled with shorter extraction times and lower energy consumption. As for the UAHE method, the CCRD yielded R² values of 81.63% for TPC and 64.37% for extraction yield. Minimal response variation occurred within the studied range, establishing optimal UAHE conditions at 40% ultrasound amplitude for 5 minutes, corresponding to a TPC of 36.68 ± 0.30 mg EAG/g DE, ORAC value of 2770.68 ± 146.99 mmol TE/g DE and, extraction yield of 3.7 ± 0.0%. Although the UAHE method resulted in a lower total phenolic content (p < 0.0001), it achieved a yield comparable to EHC (p = 0.9985) while retaining high antioxidant capacity (p = 0.9494). These findings demonstrate that integrating emerging green technologies, such as ultrasound, is a robust strategy for the sustainable recovery of phenolic compounds with high bioactivity.

Acknowledgments: FAPESP (2020/07015-7; 2023/18251-1; 2025/28441-8); CAPES/PROEX.