Application of ultrasound-microwave-assisted extraction to extract phenolic and terpenoid compounds from celery stalk

This research aimed to optimize the extraction of terpenoid and phenolic compounds from Apium graveolens L. stalks using response surface methodology. Utilizing the ultrasound-microwave-assisted extraction method, a combination of 1,2-propanediol and choline chloride (2:1 M ratio) was the most effective system. Initial single-factor experiments investigated the influence of seven independent variables on extraction efficiency (the solvent's water content, solid-liquid ratio, ultrasound temperature, ultrasound time, ultrasound power, microwave time, and intensity). The Box-Behnken Design model was used to establish the optimized conditions: 30 % (w/w) water content, a solid-liquid ratio of 1/35.33 g/mL, 5 min ultrasound time, 20 °C ultrasound temperature, 600W ultrasound power, 4.73 min microwave time, and 123 W/mL microwave intensity. Under these optimized parameters, the total phenolic content of the extracts reached 30.3 ± 0.3 mg GAE/g. The ultrasound-microwave-assisted extraction process for recovering phenolics and terpenoids relies on diffusion and a combination of diffusion and solubilization, respectively. The research suggests an effective and environmentally sustainable approach for enhancing phytochemicals' recovery from Apium graveolens L. • 1,2-Propanediol and Choline Chloride (2:1 M ratio) were the chosen DES. • SLR, USTe, MWI, MWTi were chosen for optimizing TPC. • USTe, USTi, MWI were chosen for optimizing for TTC. • Phenolic extraction suggests a diffusion mechanism. • Terpenoid extraction suggests a diffusion-solubilization mechanism.