Ultrasonic assisted extraction is a novel technique that can be applied to obtain bioactive compounds from plants with great efficiency. The aim of this study was to optimize the phenolic extraction efficiency and DPPHsc activity from the wood apple (Limonia acidissima L.) fruit. Phenols were extracted using different polar solvents, namely methanol and acetone. The conditions of extraction with the ultrasonic method using response surface methodology central composite design (CCD) and the variables include the solvent concentration of methanol and acetone (50%–100%), ultrasonic temperature (30–50°C), sonication duration (20–40 min), and ultrasonic frequency (25–45 kHz). Optimum extraction conditions were determined as follows: 61.5% of solvent concentration and extraction temperature of 50°C for 40 min of extraction time at 25 kHz ultrasonic frequency for methanol. For these extraction conditions in the case of methanol extract, the phenolic yield, total phenolic content, and DPPHsc were found to be 25.81%, 224.36 μg GAE/g, and 93.49%, respectively. For the acetone extract, optimum extraction conditions were as follows: 52.68% solvent concentration, 47.89°C temperature, 39.8 min, and 0.73 kHz ultrasonic frequency. The results obtained under these optimized conditions were 23.78% yield of phenolic extract, 290.76 μg GAE/g TPC, and 91.28% DPPHsc, for acetone. The result demonstrated that the highest phenolic efficiency, phenolic content, and DPPHsc were observed for the methanolic solvent extract. SEM images of ultrasonicated powder samples showed that sonication results in cell rupturing and thus increasing the mass transfer for bioactive compounds. Furthermore, the results of ultra-high-performance liquid chromatography (UHPLC) analysis of phenolic compounds from the methanolic extract of wood apple fruit pulp revealed the presence of gallic acid, catechin, caffeic acid, syringic acid, vanillic acid, and quercetin in a magnificent amount.

Novelty impact statement

Traditionally, solvent extraction techniques have been done in wood apple fruit; however, in this work, we add an advanced technology, the ultrasonic assisted extraction, which improves the extraction yield and efficiency of phenolic compounds using different organic solvents. After that study planned, SEM analysis shows a structural description which is evident that how this advanced technology shows a structural disruption that enhances extraction efficiency. After that study planned for chromatography by UHPLC that highlights the essential bioactive or phenolic compound obtained in the ultrasonic extract.