Abstract:

This study examined the ultrasonic-assisted extraction conditions of triterpenoids from pomegranate rind. Single
factor method and Box-Behnken experimental design were used to optimize the extraction process employing triterpenoids
yield as the response and ethanol concentration, solid/liquid ratio, ultrasonic power and extraction time as the independent
variables. Using the optimized extraction conditions, the kinetics of the extraction process was studied by establishing four
mathematical models, and the applicability of these models was analyzed by four model evaluation parameters including
coefficient of determination (R2), accuracy factor (Af), bias factor (Bf) and root mean square error (RMSE). Results showed
that the optimal extraction conditions for triterpenoids were determined as follows: ethanol concentration, 71.2%; solid/
liquid ratio, 1:20.2; ultrasonic power, 318 W; and ultrasonic time, 36.7 min. Under these conditions, the yield of triterpenoids
was 0.563%, and two nonlinear growth models, namely Sgompertz model and Logistic model, could better fit the kinetics.
Both the optimized ultrasound-assisted extraction technique and the kinetic mathematical models can be used for industrial
scale-up and optimal control of triterpenoids extraction from pomegranate rind.

Key words: pomegranate rind, triterpenoids, ultrasonic, kinetic analysis