Drying kinetics, modelling and total flavonoid content of Phyllanthus niruri L. under different drying temperature

Phyllanthus niruri L. drying kinetics were empirically examined at the temperature of 40 °C, 45 °C, 50 °C, 55 °C, and 60 °C in an air-drying oven. The herbs' aerial components (stems, leaves, and flowers) were picked after 9-10 weeks of planting. The drying procedure ended when the sample weights remained unchanged. The drying time varied from 7 to 20.5 hours. CurveExpert Professional was utilized to establish the optimal modeling fit. According to the statistical analysis, notably for the root mean square error (RMSE), determination coefficient (R²), and residual chi-square (χ²), Midilli-Kucuk has deemed the optimal function for characterizing the kinetics of P. niruri drying. The effective diffusivity and drying activation energy of P. niruri were reported to be 4.050x10^-9 m²/s - 1.620x10^-8 m²/s and 55.23 kJ/mol, respectively. UV-VIS spectrophotometry was also employed to analyze the effects of the temperature on flavonoid content. The measurement showed that the flavonoid content from all dried herbs varied from 1.18-1.69 %, which already meets the Farmakope Herbal Indonesia's standard. The highest flavonoid content was found at the lowest drying temperature.