Optimization of ultrasound-assisted extraction of amla (Emblica officinalis) fruitusing response surface methodology and identification of phenolic compounds

Amla (Emblica officinalis) fruit is rich in phenolic compounds and has antioxidant activity which is beneficial to health. The phenolic compounds of amla fruit were extracted using ultrasound-assisted extraction (UAE) method. This study aimed to optimize the extraction conditions (ethanol concentration: 48.8-91.2% and extraction time: 2.9-17.1 min) using response surface methodology to maximize the total phenolic content and antioxidant activity of amla fruit extract. Extractions at optimum conditions were compared with conventional extractions (maceration and reflux). In addition, this study also aimed to identify the phenolic compound composition of amla fruit extract using UHPLC-ESI-MS/ MS. The optimum extraction conditions were obtained at an ethanol concentration of 71.00% and an extraction time of 10.39 mins. Under optimum conditions, the actual response values of total phenolic content and antioxidant activity were close to the predicted values. The predominant phenolic compounds in the amla fruit extracts were methyl gallate, mucid acid methyl ester gallate, mucid acid dimethyl ester gallate, mucid acid gallate, mucid acid 1,4-lactone-3-O-gallate, emblicanin B, gallic acid, mucid acid lactone methyl ester gallate, digalloyl glucose, and galloyl glucose. The UAE method was more efficient for extracting phenolic compounds from amla fruit with high antioxidant activity in a shorter time than conventional methods (maceration and reflux).