Optimization of ultrasound-assisted extraction of functional polysaccharides from common mullein (Verbascum thapsus L.) flowers

Achieving a maximum extraction yield for common mullein polysaccharides (CMPs) with desirable antioxidant capacity was examined by the optimizing solvent/plant material ratio (S/PM, 10-50 v/w), and ultrasound-assisted extraction (UAE) temperature (40-80 degrees C), time (15-75 min), and power (100-500 W) using response surface methodology. The highest extraction yield of polysaccharide (5.75%) from Verbascum thapsus flowers with a remarkable DPPH-radical scavenging activity (67.66%) was resulted in the ultrasonic time of 60 min, ultrasonic temperature of 67.52 degrees C, ultrasonic power of 371.03 W, and S/PM of 40 v/w. The antioxidant activity and extraction yield obtained under the optimal UAE were noticeably more than those of the classical process. The cell morphology analysis by scanning electron microscopy revealed a more intact and amorphous matrix for intracellular CMPs extracted using the traditional method than UAE one. Structure of the mucilaginous materials with a minimum turbidity value was elucidated by Fourier transform-infrared spectroscopy (FT-IR). Practical applications Mucilages and polysaccharides have a key role in improving the emulsifying, texturizing, and antioxidant functions in food products. Verbascum thapsus is a unique herbal species with excellent medical and biological potentials. Optimization of extraction process of functional mucilages from V. thapsus flowers using powerful modeling and mathematical tools like response surface methodology (RSM) can significantly decrease the research time and cost with better results. The optimized method of ultrasound-assisted extraction ultrasound-assisted extraction (UAE) using RSM compared with the classical extraction methods can be a practical solution to improve quality and quantity of bioactive polysaccharides to incorporate into innovative food formulations.