1985 Volume 32 Issue 8 Pages 553-559
The near infrared reflectance method (NIR) was applied to determine the total nitrogen content of green tea. The infrared spectrum of green tea showed a charactaristic pattern in the wavelength region of 1100 to 2500nm comparing with the data of dried laver, wheat and soybean reported, previously. Especially, the specific spectrum pattern was indicated in the region of 2000 to 2220nm. Among about 30 bands obtained in the spectrum of green tea, some characteristic absorption bands were found. A high positive correlation was obtained between the intensity of absorbance using the second derivative (dd2log (1/R)) spectra derived from the absorption band of protein and the total nitrogen content of green tea. By the way, a stepwise multiple linear regression analysis using the second derivative selected the four wavelengths in the order of 2018, 1978, 1942 and 1333nm. The high relationship between chemically analyzed total nitrogen and the values estimated by the regression was obtained, and the correlation coefficient and the standard error of estimation are 0.995 and ±0.072, respectively.
