Ultrasonic-Assisted Deep Eutectic Solvent Extraction of Proanthocyanidins from Korean Pine Bark and Its Kinetics

Objective: The technological conditions of ultrasonic-assisted deep eutectic solvent extraction of proanthocyanidins from Korean pine bark were optimized, and the extraction kinetics equation was fitted. The purpose was to provide theoretical and technical reference for the development and utilization of proanthocyanidins from Korean pine bark. Method: Taking the yield of procyanidins as the index, the best deep eutectic solvent system was selected. The main technological parameters of ultrasonic-assisted deep eutectic solvent extraction of proanthocyanidins from Korean pine bark were further optimized by single factor combined with response surface methodology. Through the change of the yield of proanthocyanidins under different temperature and time during the extraction process, the best kinetic model of proanthocyanidins extraction was fitted and verified. Result: The results showed that deep eutectic solvent with the molar ratio of choline chloride, glycerol and water of 1:1:4 was the best solvent for extracting proanthocyanidins from Korean pine bark. The best process parameters optimized by response surface methodology were as follows: The ratio of liquid to material was 16 mL/g, ultrasonic time was 50 min, ultrasonic temperature was 55 ℃, and ultrasonic power was 480 W. The extraction effect of proanthocyanidins from Korean pine bark was the best, and the yield of proanthocyanidins was 4.11%. Boltzman model could well fit the kinetic process of ultrasonic-assisted deep eutectic solvent extraction of proanthocyanidins (R²≥0.9768), and the validation value of the model was highly ansistent with the prediction value (R²≥0.9442). Conclusion: Ultrasonic-assisted deep eutectic solvent could effectively promote the mass transfer of proanthocyanidins from Korean pine bark, and Boltzman model was determined to be the best kinetic model for extraction of proanthocyanidins. The extraction process could also provide reference for the extraction of relevant natural active substances.