Abstract
The extraction of phytochemical compounds from intact red sorghum grains was developed as an alternative process for producing bioactive material in the pharmaceutical industry. A mechanistic model is needed to better understand the process and enable predictive simulations for designing commercial-scale extraction systems. This paper presents a mathematical model for predicting phytochemical concentrations in the solvent and inside the pericarp of the grain at different positions during the extraction. The model is based on the mass transfer mechanism from inside the pericarp to its solid surface by diffusion, and then from the surface to a solvent during the extraction of bioactive compounds. It was numerically solved while using finite-difference approximation. The parameters considered were effective diffusivity inside the pericarp (Dep), mass transfer coefficient from the pericarp surface to the solvent (kc), and distribution coefficient (H). The model simulates the extraction performance, including the yield and bioactive compounds’ concentrations in the extract and inside the pericarp at various positions and times. A sensitivity analysis of the changes in each involved parameter provided sufficient information for increasing the performance of the model. A validation test that compared the results of the simulation with those of established analytical solutions showed that the model has high accuracy. Hence, the model can be applied in quantitative evaluations to improve productivity in the pharmaceutical industry.
Highlights
The development of extraction methods to obtain phytochemical compounds from plants as a source of food supplements and medicines remains attractive [1,2,3,4]
The results of this study are presented in the following sequence: (1) simulation results; (2) results of the sensitivity test to explore the effect of parameter values on the simulation results; (3) model validation and analytical results for simple cases; and, (4) results of the model’s validation with respect to the obtained experimental data
The trial simulation was performed under the extraction conditions, in which 20 sorghum grains were extracted in 500 mL of aqueous water
Summary
The development of extraction methods to obtain phytochemical compounds from plants as a source of food supplements and medicines remains attractive [1,2,3,4]. Several methods have been applied to improve the extraction process in the pharmaceuticals and food industry [5,6] This interest is related to the increasing public demand for natural medicines [7]. The phytochemical compounds in red sorghum, including polyphenols, phenolic acids, flavonoids, and condensed tannins of proanthocyanidins [9], are concentrated on the external layer of the grain, which is known as pericarp. These compounds have proven to have beneficial health effects, such as antioxidant, anti-proliferative, UV adsorption, and antimicrobial activities [9,10,11]. The antioxidant activity of proanthocyanidins has been evaluated on the basis of Processes 2019, 7, 837; doi:10.3390/pr7110837 www.mdpi.com/journal/processes
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