Xanthones from Mangosteen Pericarp ( <i>Garcinia mangostana</i> L.) Are Effective Natural Antioxidants for Mitigating Sensory Deterioration in Lemon Beverages by Slowing Citral Oxidation

Citral (3,7-dimethyl-2,6-octadienal) is a key volatile flavor constituent in lemon essential oils. However, its instability in acidic, aqueous, and oxidative environments can lead to degradation and off-flavor volatile organic compound (VOC) formation. We reported herein an effective water-based alkaline solubilization and acid precipitation (ASAP) for extracting xanthones from mangosteen pericarp as natural antioxidants. The ASAP-derived mangosteen pericarp extract (MP-P), rich in xanthones (∼90%), was assessed for its efficacy in inhibiting off-flavor VOC formation in lemon beverages (pH ∼3.5) stored at 38 °C for 6 weeks using HS-SPME-GCMS and sensory evaluation. MP-P markedly suppresses citral oxidation indicators, such as p -methylacetophenone and p -cresol, by 73.96–93.94 and 48.72–60.94%, respectively, while improving the beverages’ sensory qualities. HPLC-PDA and LC-ESI-QTOF-MS/MS identified γ-mangostin and α-mangostin as major phenolic contributors to antioxidant activity. Overall, MP-P is a promising natural antioxidant with peroxy radical-scavenging capacity, promoting sustainability and offering industrial benefits in the beverage sector.