Kinetics of extraction of biologically active substances from medicinal plant raw material Tagetes erecta L.

Abstract

The work investigates the kinetics of periodic processes of extraction of bioactive substances from marigold plant raw materials. For a unified description of maceration, percolation, digestion and re-maceration, a two-stage kinetic model is used, which takes into account the sequential action of internal diffusion and external mass transfer resistances. It is shown that the kinetics of the process is adequately described by a generalized first-order equation using the effective mass transfer coefficient K. Based on the analysis of experimental kinetic curves and their linearization, differences in mass transfer modes for different extraction methods were established. Maceration is characterized by a diffusion-controlled regime and minimal K values, while percolation provides the highest process intensity by reducing external mass transfer resistance. Digestion and re-maceration occupy an intermediate position, combining temperature and hydrodynamic intensification. The regularity of the increase in the mass transfer coefficient in the series: Kmac < Kdig < Kremac < Kperk has been established. It has been shown that the internal diffusion coefficient significantly depends on the morphological and anatomical features of the raw material, and an increase in temperature contributes to the intensification of the extraction process. The results obtained can be used to optimize the regimes of periodic extraction of bioactive substances from plant raw materials.