Effect of soaking pretreatment on kinetics of total phenolic compound extraction from Eryngium Caucasicum Trautv leaves using ultrasound waves

In this study, the effect of soaking pretreatment on kinetics of bioactive phenolic compound extraction from Eryngium caucasicum Trautv leaves using ultrasound-assisted extraction (UAE) under optimized conditions (50% amplitude, 42 ºC temperature and 51 min sonication time) was investigated. The soaking pretreatment independent variables were time (30, 60 and 90 min) and temperature (25, 35, 45 and 55 ºC). The kinetics of bioactive phenolic compounds extraction was studied using Pelegʼ s model. The high value of correlation coefficient (R2 > 0.98) and low values of root mean square error (RMSE < 0.160) and mean relative deviation modulus (E<0.44) revealed that Pelegʼs model could applied successfully to describe the kinetics of bioactive phenolic compounds extraction. The experimental results showed that soaking pretreatment had significant (P<0.05) effect on improvement of UAE of bioactive phenolic compounds. Swelling index and total phenolic content obtained using the best conditions of soaking pretreatment (temperature of 45 ºC and 60 min) were 14.50 ± 0.05 mL/g and 95.50 ± 0.11 mg GAE/g, respectively. Under these conditions, the radical scavenging activity of extract was 67.20% ± 0.15 of DPPH free radical scavenging activity and 36.11% ± 0.12 of OH free radicals scavenging activity. In addition, the Peleg rate constant (K1) was 0.009639 min.g/mg under the best conditions.