Ultrasound-assisted cloud point extraction of phenolamide from rose residues: optimization, characterization and...

Rose essential oil production generates large amounts of solid residues, which remain underutilized despite their richness in bioactive compounds. Profiling of the rose residues in this study identified N¹, N⁵, N¹⁰-(E)-tri-p-coumaroylspermidine (ETCS), a representative bioactive phenolamide. Following that, an ultrasound-assisted cloud point extraction (UA-CPE) strategy was developed to recover ETCS from these residues. The optimized extraction conditions were 5% (w/v) Brij 58, a solid-to-liquid ratio of 1:40 (g/mL), and a nominal ultrasonic power of 480 W at 50 °C for 30 min. The ETCS yield reached 2.86 ± 0.15 mg/g, which was approximately 80% higher than that obtained by ultrasound-assisted ethanol extraction. Subsequent phase separation (10% (w/v) Na₂SO₄, pH 4.0, 35 °C) achieved a 7.1-fold concentration factor with 98% recovery. Greenness and practicality assessments using AGREE, AGREEprep, and BAGI indicated favorable greenness and laboratory-scale practicality of the developed method. Instrumental characterization and DFT calculations suggested that ETCS may associate with the relatively hydrophilic POE region of Brij 58. Overall, these findings support UA-CPE as an efficient strategy for the recovery and preconcentration of ETCS from rose residues, thereby contributing to the value-added utilization of rose byproducts.