Extracting Kinetic Model for Natural Pigment Production from Monascus Purpureus using CFD Simulation

Due to the increasing consumption of pigments in various industries, especially the food and cosmetic industries, the production of natural pigments is expanding. Monascus purpureus has a special place in this industry as a source for pigment production, and one of the methods of using it is submerged fermentation in a bioreactor. In the present study, the production of red pigment from Monascus purpureus in a stirred bioreactor was investigated and simulated by CFD. The simulation was done using COMSOL Multiphysics software in 3D mode. Fluid mechanics and mass transfer and four kinetic models of Monod, Tessier, Moser, and Haldane were investigated and the results of each model were compared with the experimental data. Then the Monod model was recognized as demonstrating major agreement with the experimental data of placement simulation and maximum specific growth rate of 0.8 h−1 and saturation constant of 0.2 mg/l. Yeast extract and stirrer speed were considered as the investigated variables. The graphs of time, location, and speed-location of the process were checked and according to the obtained results, it was found that by increasing the yeast extract and also by increasing the speed of the stirrer, pigment is produced at a higher level. The result obtained from this simulation was shown with a correlation coefficient of 0.99 by the results obtained from the laboratory results.