Optimization of ultrasound-assisted extraction of phenolic compounds from Ziziphus jujube Mill. leaves using response surface methodology

Abstract

The phenolic compounds in jujube (Ziziphus jujuba Mill) leaf were extracted using ultrasound assisted extraction (UAE) for potential of antioxidant food additive in this study. The extraction factors such as methanol concentration, temperature and time were optimized using response surface methodology (RSM) to maximize of the total phenolic content (TPC), 2,2 -diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and phenolic profile in jujube leaf extracts (JE). The best possible range for methanol concentration (25-50%), duration of ultrasound (20-40 min), ultrasonic temperature (40–60 °C) were obtained using the Box-Behnken design (BBD). The optimum extraction parameters were obtained with 25% methanol concentration, 20 min duration of ultrasound and 49.89 °C ultrasonic temperature. Ellagic, caffeic, rosmarinic acid, and rutin were determined as major phenolics in JE under optimal extraction parameters. The results revealed that UAE is an effective pretreatment for extracting bioactive ingredients from JE as potential functional food additive. Furthermore, RSM is an effective method for optimizing the UAE factors.