Statistical modeling and optimization of ultrasound-assisted deep eutectic solvent extraction for ferulic acid recovery from fruit waste

Ferulic acid (FA) is a phenolic compound and has been widely regarded for its high antioxidant, anti-inflammatory, and photoprotective activities which finds it useful in pharmaceutical, nutraceutical as well as cosmetic products. The extraction of ferulic acid by the conventional solvent-based methods from the plant materials mostly are faced with the following problems low efficiency and solvent toxicity, and pose environmental issues. To address these issues, this study was carried out to develop and optimize eco-friendly extraction process using ‘Deep Eutectic Solvents’ (DES) for efficient recovery of ferulic acid from fruit-waste. This study screened different DES systems such as Choline-chloride and glycerol, Choline chlroide and acetic acid, Choline chloride and ethylene glycol and Choline chloride and citric acid. Among them, choline chloride with glycerol showed efficient system for extraction of ferulic acid-rich extract. Further to improve the extraction of FA-rich extract, a statistical approach was adopted. The process parameters such as water content in DES, DES volume, and ultrasonication time, were considered for optimization using central composite design (CCD) and showed optimal yield of 170 mg/gdw at 25% water content, 30 mL DES volume and 25 min ultrasonication time. The mathematical model predicted a maximum FA-rich extract yield of 165 mg/gdw under optimized conditions, which closely matched the experimentally obtained yield of 170 mg/gdw, confirming the reliability of the statistical model. Further extracted FA-rich extract was characterized using Thin Layer Chromatography (TLC) with commercial FA as standard. The purity and concentration of extracted FA was quantified using High-performance liquid chromatography (HPLC) and found to be 37 mg/gdw. The FA extracted using the UAE-DAE system showed high antioxidant properties. This is the first report to our knowledge to extract FA using DES integrated UAE system and also the highest FA yield of 37 mg/gdw.