Optimizing mucilage extraction from Plantago major seeds using response surface methodology for enhanced functional characteristics

The present research was conducted to optimize mucilage extraction from P. major seeds by varying key factors, including pH, temperature, liquid-to-solid ratio, and treatment time, over a wide range of conditions using a Rotatable Central Composite Design (RCCD) of Response Surface Methodology (RSM). Infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray analysis, and powder X-ray diffraction revealed the presence of significant functional groups, composition, morphology, and the amorphous nature of the mucilage. The results indicate that mucilage recovery from seeds varied significantly (p ≤ 0.05) across the tested pH range (3.5–11), temperature (41–95 °C), liquid-to-solid ratio (65–95 mL/g), and treatment time (45–195 min). The highest mucilage yield (25 g/100 g) was acquired with a treatment time of 170 min and a liquid-solid ratio of 90 mL/g at 50 °C and pH 4.75. The FTIR band at 3300 cm^− 1 confirmed the polysaccharide nature of mucilage. SEM revealed a pore size of 61–144 µm (average pore size 110 µm), while EDX analysis disclosed the elemental composition of mucilage. The mucilage exhibited an exceptional water-holding capacity, swelling in deionized water (DIW) and phosphate buffers (pH 6.8 and 7.4), and deswelling in acidic buffer (pH 1.2), salt solutions (KCl, NaCl, and MgSO₄), different temperatures (25, 37, and 50 °C), and an organic solvent (ethyl alcohol), following second-order kinetics. The mucilage depicted reasonable antioxidant activity when studied using the DPPH assay. Ocular testing established mucilage as a non-irritating and non-toxic biomaterial. Finally, the non-thrombogenic and non-hemolytic potential of mucilage was confirmed via hemocompatibility studies. The mucilage displayed prominent swelling capacity (45.70 ± 2.00 g/g), centrifuge retention capacity (76.40 ± 1.11%) and intrinsic viscosity (12.08 ± 0.18 at 20 ºC). The findings underscore the promising industrial potential of mucilage, supporting its future application in various commercial sectors.