Insights into the major phenolic acids in Perilla frutescens obtained by a sustainable procedure

[Display omitted] •Rosmarinic acid (RA) was the main biological polyphenol in Perilla frutescens.•An ultrasound-assisted supercritical CO2 (USCCO2) procedure efficiently extracted RA.•Second-order rate model confirmed that the USCCO2 extraction has the best efficiency.•Mass transfer model further demonstrated the superiority of USCCO2 for RA extraction.•Interface transfer and diffusion were the dominant processes in the USCCO2 procedure. This research was performed to evaluate the efficiency of ultrasound in obtaining the total extract, caffeic acid and rosmarinic acid from Perilla frutescens using supercritical CO2 (USCCO2) extraction. Compared with traditional heat-reflux, ultrasonic-assisted and SCCO2 extractions, the USCCO2 technique decreased the extraction duration (1.12–1.92 times) and the consumption of solvent (1.90–285.71 times) at lower extraction temperatures and obtained a higher yield from the plant matrix. Furthermore, a second-order kinetic model and Fick’s second diffusion model were implemented to ascertain the extraction rate constant, equilibrium concentration, initial extraction rate, effective diffusion coefficient, mass transfer coefficient, Biot number, equilibrium constant and thermodynamic parameters of the USCCO2 and SCCO2 dynamic extractions of rosmarinic acid from P. frutescens. These results provide valuable insights into the kinetic and mass transfer behaviors that occur during the USCCO2 and SCCO2 procedures and explain the reasons for the better extraction efficiency of the former procedure.