Green ultrasound-assisted extraction, purification, characterization and stability kinetics of anthocyanins from Rosa chinensis Jacq.

Rosa chinensis Jacq. petals are a rich, underutilized source of anthocyanin pigments, but these compounds are highly sensitive to light, temperature, and pH, and conventional extraction methods are often solvent-intensive, energy-demanding, and damaging to pigment stability. A food-grade, green ultrasound-assisted extraction (UAE) strategy was therefore developed and optimized using single-factor experiments followed by a three-factor, three-level Box-Behnken design, to establish an efficient and scalable protocol for recovering rose anthocyanins. Extraction temperature and time were identified as the most influential factors, and the optimal conditions were 60% (v/v) ethanol and 40% (v/v) aqueous citric acid (2% w/v), 36.3 °C, a solid-to-liquid ratio of 1:49.4 g mL-1, and 23.9 min, yielded 34.99 g kg-1 dry weight (DW) anthocyanins. Macroporous resin purification (Amberlite XAD-7HP) enriched the pigment fraction, and LC-ESI-MS/MS confirmed three anthocyanins at MSI confidence Level 2, with cyanidin-3,5-O-diglucoside as the dominant compound. The purified extract exhibited first-order thermal degradation kinetics (Ea = 67.50 kJ mol-1) and excellent stability under pasteurization conditions (70 °C, t1/2 = 12.6 h), along with substantial pigment retention after ten days of light (69.8%) and dark (82.3%) storage. Strong antioxidant activity was confirmed by DPPH and ABTS assays (TEAC of 2036.39 and 1455.15 mmol TE g-1 DW, respectively). These findings establish Rosa chinensis Jacq. as a stable, potent source of natural anthocyanin colorants and antioxidants with promising potential as functional ingredients in food and nutraceutical applications.