Ultrasound-assisted extraction using [BMIM][Cl] ionic liquid as an effective method for recovering phenolic compounds from the coproduct of guava processing

Ionic liquids (IL) are an innovative alternative to organic classic solvents for recovering phenolic compounds. In this study the influence of different parameters for the extraction of phenolic compounds from red guava coproduct using the ionic liquid [BMIM][Cl] associated with ultrasound-assisted extraction (ILUAE) was compared to methanolic extraction. The IL [BMIM][Cl] was synthesized and characterized by its melting point and MS/MS fragments. A full factorial design 23 was used to evaluate the effects of the concentration of [BMIM][Cl], extraction time, and temperature on the total phenolic content (TPC) and antioxidant activity (DPPH) of the obtained extracts. An IL concentration of 2.5 mol L-1, extraction time of 10 min at 35 °C showed the highest amount of TPC (4.01 mg g-1 gallic acid). The highest AA (8.77 mg g-1 ascorbic acid) was reached using an IL concentration of 2.5 mol L-1, extraction time of 40 min at 55 °C. These results were superior to those obtained for methanol extraction (1.58 mg g-1 gallic acid, and 3.65 mg g-1 ascorbic acid, respectively). The results indicated that the innovative extraction method using ILUAE was quick, straightforward, and effective for recovering valuable bioactive compounds from red guava coproduct without using organic solvents.