Fig. 1. Schematic diagram of transmission terahertz time-domain spectroscopy system

Fig. 2. Terahertz absorption spectra of eight flavonoids

Fig. 3. Temperature dependent of absorption spectra of naringenin and daidzein

Fig. 5. Quantitative analysis of different concentrations of naringenin and daidzein in starch
(a) and (c) are terahertz time-domain spectra of naringein and daidzein with different concentrations;(b) and (d) are the predicted results of naringenin and daidzein