Study on Terahertz Time-domain Spectral Signatures of Wheat from Different Years

Wheat freshness is an important factor affecting wheat quality. In the current research, a total of 375 wheat samples from five different years (2016, 2017, 2018, 2019 and 2020) were identified by using the terahertz time-domain spectroscopy (THz-TDS) technology. The THz spectrum information of wheat was acquired, and the THz-TDS signals of wheat were obtained after Savitzky-Golay pretreatment. Then the data of frequency-domain spectra, refractive index spectra and absorption spectra of wheat within the range of 0.2∼1.4 THz were obtained after calculating the optical parameters. According to the experiment results, there were differences in the refractive indexes and absorption coefficients of wheat samples from different years. The refractive indexes of wheat samples from 2020 were significantly lower than that of wheat samples from other years, and the absorption coefficients of all five kinds of samples increased as the frequency increased. The study results showed that THz-TDS was of great potential for the effective determination of wheat freshness and it provided a basis for determination of wheat quality, bearing great practical significance.