Vacuum-pulsating ultrasound synergy for efficient extraction of bioactive substances from Lonicera japonica

This study presents a vacuum pulsating ultrasound extraction (VP-UE) technique for extracting bioactive compounds (chlorogenic acid(CGA),total flavonoids(TF),polysaccharides(PS)) from uncrushed and microcrushed Lonicera japonica (Flower bud) under laboratory-scale conditions. By combining vacuum pulsation and ultrasonic cavitation, VP-UE creates a bimodal pore structure (macropores and micropores) in the material, enhancing mass transfer and solvent contact. Under optimized conditions (200 W, 25 min,50℃,solid-liquid ratio1:30, 3 pulsation cycles), extraction yields exceeded 90% of those from fully pulverized materials, reaching 2.49% for CGA, 1.27% for TF, and 5.53% for PS. Heatmap analysis revealed correlations (r > 0.8) among the three active compounds, suggesting strong co-extractability under VP-UE conditions, though further pathway analysis is needed. Color parameters (L*, a*, b*) linked PS extraction to colloidal turbidity (L* decrease) and flavonoid pigments to yellow hue. VP-UE is a promising extraction method at the laboratory scale, offering insights for equipment design and extract quality evaluation.