Effects of dielectric barrier discharge (DBD) plasma on the drying kinetics, color, phenolic compounds, energy consumption and microstructure of lotus pollen

This work investigated the influences of dielectric barrier discharge (DBD) plasma on the drying characteristics, color, and phenolic acid content of lotus pollen. The microstructure was also evaluated to reveal the mechanism of the changes in the quality of lotus pollen. Results showed that the drying time of lotus pollen was reduced from 28 to 4 h when the drying voltage increased from 0 kV to 40 kV. Further, the DBD plasma-dried sample exhibited better color. Compared with the fresh sample, the vanillic acid content in natural open sun drying decreased by 22.7%, while the vanillic acid content of DBD plasma-dried sample increased by 47.9%. Interestingly, ferulic acid was converted into vanillic acid during DBD plasma drying. Total energy consumption was three to four orders of magnitude higher than net energy consumption. The microstructure observation elucidated the mechanisms of moisture migration and change of phenolic acid during DBD plasma drying.