Optimization and Kinetic Modelling of Hydroxycinnamic Acid Extraction from Anethum graveolens Leaves

This study focused on optimizing key extraction parameters (ethanol concentration, temperature, and time) to enhance the extraction of hydroxycinnamic acids from A. graveolens leaves, applying a replicated 23 full factorial design. The experimental results demonstrated that extraction conditions significantly influenced the yield of hydroxycinnamic acids. The optimum conditions were 50% ethanol for 80 min at 50 °C, yielding 103.75 µg/g of chlorogenic acid (ChA), 6.05 µg/g of ferulic acid (FA), and 2.19 µg/g of sinapic acid (SA). Therefore, the extract obtained with 50% ethanol showed the highest levels of polyphenols, flavonoids, and antioxidant potential, highlighting its suitability for use in both food-related products and pharmaceutical formulations. Additionally, the applicability of different mathematical models (unsteady-state diffusion, parabolic diffusion, and power law models, as well as Ponomaryov’s and Elovich’s equations) to describe and better understand the kinetics of hydroxycinnamic acid extraction from dill leaves was evaluated. The fit of each kinetic model to the experimental data was assessed using the root mean square error and the coefficient of determination. Among the five kinetic models, the unsteady-state diffusion model and Ponomaryov’s equation provided the best fit, exhibiting the highest accuracy. The activation energy for the extraction process was determined to be 5.85, 6.46, and 7.59 kJ/mol for ChA, FA, and SA, respectively. The extraction of hydroxycinnamic acids from dill leaves was found to be endothermic, irreversible, and spontaneous.