Mechanism of Microwave Effect on the Extraction Process of Tea Polyphenols

Microwave-assisted extraction (MAE) is an effective method for extracting tea polyphenols. However, the research on MAE mainly focuses on experimental methods, which not only leads to a large amount of experimental work but also generates a lot of material waste. In addition, due to the lack of mechanism research, it is difficult to find a more effective method. In this study, based on electromagnetic field theory, the heat and mass transfer model of tea polyphenol extraction is established based on measuring the dielectric properties of the extract. The distribution of temperature, diffusion coefficient, and flow rate of microwave-assisted extraction of tea polyphenols are all analyzed in detail. The results show that the temperature distribution in the extraction system is uneven. The middle temperature of the extraction solution is high and the edge is low. Moreover, with the increase of microwave power and extraction temperature, the diffusion coefficient is gradually increased, and the flow rate increases, which is more conducive to the extraction process as time goes by. This study provides a theoretical basis for the microwave-assisted extraction of tea polyphenols, reducing experimental workload and material waste.