A cyanidin-3-O-rutinoside dominant anthocyanin system from Osmanthus fragrans fruit peel: Composition, color behavior and thermal stability

This study evaluated Osmanthus fragrans fruit (OFF) peel as a potential source of anthocyanin-based natural colorants. Anthocyanins were extracted using acidified ethanol and purified by macroporous resin adsorption, yielding a pigment-rich extract with a recovery of 10.4 ± 0.2% from dried peel. HPLC–MS/MS analysis indicated that cyanidin-3-O-rutinoside (C3R) was the predominant anthocyanin in the extract. The molar absorptivity of C3R was experimentally determined to enable more accurate quantification of C3R-rich systems. The purified extract exhibited typical pH-dependent color behavior, maintaining a stable red coloration under acidic conditions (pH 2.0–4.0). Thermal stability experiments showed that C3R degradation was strongly influenced by temperature and pH, and the degradation behavior followed first-order kinetics. In addition, the extract displayed measurable antioxidant capacity in DPPH and FRAP assays. These results demonstrate that O. fragrans fruit peel is a promising source of C3R-rich anthocyanins with potential applications as natural colorants in acidic food systems.