A biorefinery approach for the simultaneous obtention of essential oils, organic acids and polyphenols from citrus peels: Phytochemical characterization and bioactive potential
Esther Gómez-Mejía, María Inês Días, Carla Pereira, Tânia C. S. P. Pires, Jesús Palá‐Paúl, Noelia Rosales‐Conrado, María Eugenia León‐González, Ricardo C. Calhelha, Custódio Lobo Roriz
Abstract
This investigation evaluates the valorization of citrus peels (lemon, tangerine, and orange) to recover both on-polar and polar fractions simultaneously. Citrus essential oils, abundant in limonene (74.4–33.7 %), exhibited great antioxidant activity (IC 50 = 2.002 mg/mL) and Campylobacter jejuni halo inhibition (2.9 cm), particularly in tangerine and orange essential oils. The aqueous extracts were rich in quinic and malic acid (10–78.8 g/100 g), along with polyphenols (22.7–5.2 mg/g), such as diosmetin, luteolin, and eriodictyol glycosides. Tangerine's aqueous fraction showed the highest inhibition of oxidative hemolysis (IC 50 = 102 μg/mL) and Staphylococcus aureus (MIC = 2.5 mg/mL). Whereas lemon was most effective against lipid peroxidation (IC 50 = 1.33 mg/mL) and gastric adenocarcinoma proliferation (IG 50 = 83 μg/mL). Principal component analysis correlated the in vitro bioactivities with each compound and citrus type, underscoring the potential of citrus peels as a cost-effective, sustainable source of value-added compounds with tailored commercial applications.