Sequential Extraction of Naringin and Low-Ester Pectin from Naturally Dropped Fruit of Pomelo

Naringin and pectin were innovatively and sequentially extracted from naturally dropped fruit of pomelo (NDFP), optimizing yields via response surface methodology (RSM). Under optimized conditions, naringin was extracted first with 70% ethanol (70 °C, 110 min, SSR 15:1 <i>v</i>/<i>w</i>), followed by pectin extraction from the residue using pH 1.50 acetic acid (80 °C, 160 min, ratio 40:1 <i>v</i>/<i>w</i>) naringin yield reached 42.77% with 97.6% ± 0.31% HPLC purity, while pectin yield was 14.32%. Critically, the recovered pectin was identified as low-ester and exhibited significantly superior antioxidant activity compared to commercial pectin. This work establishes an efficient sequential extraction process valorizing waste pomelo drop, yielding high-purity naringin and antioxidant-rich, low-ester pectin.