Optimized High-Pressure Ultrasonic-Microwave-Assisted Extraction of Gingerol from Ginger: Process Design and Performance Evaluation

Abstract

This study employed high-pressure ultrasonic-microwave-assisted extraction (HP-UMAE) to extract gingerols from ginger. The extraction yield and total polyphenol content of the extracts were determined. Their antioxidant activity was assessed by DPPH and ABTS radical scavenging assays, and compared with extracts obtained by leaching extraction, reflux extraction, ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE), and ultrasonic-microwave-assisted extraction (UMAE). The results demonstrated that HP-UMAE achieved the highest extraction yield and the strongest ABTS radical scavenging activity among the evaluated methods. Furthermore, HP-UMAE extracts exhibited the highest concentrations of key gingerol constituents: 6-gingerol (14.29 mg/L), 8-gingerol (0.38 mg/L), 10-gingerol (1.95 mg/L), and 6-shogaol (4.32 mg/L). This enhanced efficacy is attributed to the synergistic combination of ultrasonic cavitation and microwave-induced thermal effects under elevated pressure. This synergy creates conditions promoting cellular wall disruption, facilitating the release of intracellular components, while concurrently enhancing solvent penetration and gingerol solubility. Scanning electron microscopy (SEM) analysis confirmed the significant structural damage inflicted on ginger cell walls following HP-UMAE treatment. The process parameters for HP-UMAE were optimized using single-factor experiments. The optimal extraction conditions were determined as follows: microwave power 800 W, ultrasonic power 1000 W, liquid-to-solid ratio 55:1, and temperature 100 °C (corresponding pressure 2 MPa). Under these optimized parameters, the extraction yield and ABTS radical scavenging rate reached their peak performance, yielding values of 4.52% and 43.23%, respectively.