Abstract:In this paper, based on the mass transfer theory and the principle of conservation of mass, a reasonable assumption was made regarding the mass transfer process, wherein the active ingredients in natural plant were transferred from solid phase to liquid phase. The kinetic models of the subcritical water extraction (SWE) and ultrasound-assisted subcritical water extraction (USWE) of the active ingredients of natural plants were established based on Fick’s second law of diffusion. A method for estimating the yield of active ingredients from SWE and USWE was established. The extraction of cinnamaldehyde (the principal component) from cinnamon was used as an example. Temperature,the most important factor affecting the cinnamaldehyde yield, was used as the indicator for conducting the experimental validation of the kinetic models of the SWE and USWE of cinnamaldehyde at different temperatures. The kinetic model of the extraction was . The model validation proved that this kinetic model fitted well with the experimental data from the extraction. The and values of USWE were higher than those of SWE, showing that ultrasound could enhance the extraction efficiency of SWE. The kinetic model provided a theoretical reference for the SWE and USWE of active ingredients from plants for industrial applications and for expanding the scope of SWE and USWE applications.
