Ultrasound-assisted extraction, optimisation using response surface methodology and HPLC-DAD phenolic compounds quantification from S. peels cultivated in Tunisia.

A new ultrasound-assisted extraction method was developed for the determination of phenolic compounds extracted from peels cultivated in Tunisia. Several extraction variables including: extraction time, temperature, liquid/solid ratio and pH have been studied using response surface methodology. The extraction efficiency was evaluated by measuring the total phenolics; flavonoids and antioxidants content. The highest values of the studied response were observed after 9.78 min at 49.64 °C in a liquid-to-solid ratio 22.07 ml/g and in pH (5.54). The individual phenolic compounds content of the optimum extract peels of the Sims have been analysed using HPLC-DAD. The results revealed the presence of gallic followed by caffeic acids, while the apigenin-7-glucoside and rutin have been quantified as the abundant flavonoid compounds (0.653 and 0.488 mg/ml, respectively). This green procedure should be a promising option to guide industrial design for the production of phenolic-rich plant extracts.