Optimization of microwave assisted extraction of anthocyanins from blueberry and its thermokinetic analysis

Objective: To improve the extraction rate of blueberry anthocyanins and overcome the shortcomings of traditional extraction. Methods: Firstly, single factor experiment was used to explore the effects of four experimental factors on the yield of anthocyanins. Response surface methodology was used to design the combination experiment, and genetic algorithm was employed to optimize the extraction process. The dynamic model of MAE process was established based on Fick's first law. According to Arrhenius equation and phase transition equilibrium principle, Ea, ΔS, ΔH, and ΔG in the extraction process were obtained to analyze the thermodynamics of microwave extraction process. Results: The optimum extraction parameters to achieve the highest yield of anthocyanins （83.15±2.03）% from blueberry via MAE were obtained at extraction temperature of 60 ℃, extraction time of 8 s, ethanol concentration of 57%, and solid-to-liquid ratio of 1∶32 （g/mL）. The established kinetic model could predict the extraction effect of anthocyanins at different extraction temperatures. In the process of microwave extraction, the Ea, ΔS, and ΔH were 40 510 J/mol, 42.07 J/mol, and 190.64 J/mol, respectively. ΔG was less than zero, indicating that the microwave extraction process belonged to endothermic, entropy increasing and spontaneous process. Conclusion: The results provide theoretical basis and reference for the efficient extraction and deep development of anthocyanins.