Kinetics of Luteolin Extraction from Peanut Shells and Reseda luteola for Potential Applications as a Biofunctional Ingredient

This study investigates the extraction kinetics of luteolin, a bioactive flavonoid with recognized antioxidant and health-promoting properties, from the aerial parts of Reseda luteola (dyer’s weld), with emphasis on its industrial potential. A comparative analysis with peanut shells (Arachis hypogea) identified R. luteola as a superior source, containing 14 ± 3 mg of LUT/g of material, approximately eight times higher than the amount in peanut shells. Luteolin occurred predominantly as luteolin-7-O-glycoside (57%) and the aglycone (35%). Methanolic semi-batch extraction at 25 °C yielded 9.6 mg LUT/g (70%) within 60 min at a solid-to-liquid ratio of 1:9, demonstrating significantly greater solvent efficiency than conventional Soxhlet or maceration techniques. Kinetic modeling, based on Fick’s second law, revealed a biphasic process with a low rate constant ratio (3:1) between the two stages, indicating the need for process optimization. These results establish R. luteola as a cost-effective and sustainable source of luteolin for dietary supplements and functional foods, while indicating the need to explore alternative solvents and advanced extraction methods to further optimize yield and efficiency.