Development of ohmic-assisted green extraction technique with ultrasonic and microwave pretreatments: Burdock (Arctium lappa L.) root extract

The present study was carried out to investigate and optimize the recovery of Burdock (Arctium lappa L.) root extract (BRE) using Ohmic-assisted (OH) extraction method with ultrasonic (US-OH) and microwave (MW-OH) pretreatments. Initially the optimized OH condition was obtained with the aim of maximizing the extraction efficiency and total phenol content. Then, the effect of pretreatment time (20, 40 and 60 min), ultrasonic amplitude (50 and 100 %) and temperatures (30, 40 and 50 °C) in US-OH, and powers (100, 300 and 450 W) in MW-OH were investigated. Finally, optimized OH, US-OH, and MW-OH extraction methods were compared with the heat assisted extraction method (HAE). The results showed that all the main and interaction effects were significant in OH, US-OH, and MW-OH extraction methods (p < 0.05) and only the interaction effects on total phenolic content (TPC) were not significant in the OH method (p > 0.05). The voltage gradient equal to 12.8 V/cm, extraction time equal to 20.72 min and extraction temperature equal to 50 °C were obtained as optimal conditions in the OH extraction of BRE. Ultrasonic amplitude, extraction temperature and ultrasonic time 100 %, 50 °C and 40 min respectively were obtained as the optimum US-OH extraction method. According to the results of chemical compounds, microbial and morphological assays, extraction using pretreatment methods of ultrasound, microwave in ohmic heating, respectively, showed an improvement in the quality of the extraction compared to the conventional (HAE) method.