Purification of a Plant-Based Bioactive Compound Aided by Geometric Calculation of a Quasi-Ternary Phase Diagram: The Case of Piperine

Abstract

In the integrated isolation and purification of a plant-derived product substance, maintaining a consistent final purity and yield may not be straightforward due to the fluctuations in the initial content of the desired substance, an aspect that is often neglected when the parameters are built based on empirical foundations. To answer this problem, the concept of a quasi-ternary phase diagram, where the solvent quantity for purification is mapped as a function of the impurity content, can be used. Yet, constructing a phase diagram for such a complex mixture, while possible, is a taxing effort. On the other hand, an equilibrium tie-line prediction method by harnessing the geometric shape of the quasi-ternary phase diagram may offer a more straightforward estimation. This method assumes an equal tie-line node distribution in the lower and upper boundaries of the phase diagram. In this work, the predictive capability of this approach was tested against the case study of piperine purification from a black pepper extract. By this method, a dynamic purification process by antisolvent crystallization was demonstrated. Despite some differences between the predicted purity and yield against the reality, pure piperine solids could be produced from the black pepper extract with the purity and yield of 98.9 ± 0.3 and 1.0 ± 0.4 wt %, respectively. In addition, the quasi-ternary phase diagram also provided useful information about the necessity of saponification before crystallization from a plant-based extract.