Application of FT-NIR in rapid and simultaneous determination of physical and chemical indices of tobacco flavor and fragrance
Flavor and fragrance play a key role in cigarettes. Therefore, it is very important to control the qualities of these additives. The current method of quality control is to determine physical and chemical indices of tobacco flavor and fragrance, but it is complicated to measure so many indices one by one. The objective of this study was to use FT-NIR for rapid and simultaneous determination of four physical and chemical indices including refraction index, pH, relative density and total volatile constituents. Spectra of 18 different kinds of samples were collected to develop calibration models using partial least squares (PLS). The effect of spectra pre-treatment on models had been studied, and it was indicated that second-derivative transformation of spectra could improve the models' performance. To avoid low signal-to-noise ratio, only wavelengths in the region of 6200-5500cm-1 were employed for the calculations. The correlation coefficients of four models were 0.99926, 0.99106, 0.99990 and 0.99527 with the RMSEC values of 0.000844, 0.127, 0.00183 and 2.01, respectively. At the same time, the reliability and repeatability of this method were evaluated. Result showed that this method was applicable for four indices of different flavor and fragrance, and the RMSEP values were 0.00182, 0.374, 0.00393 and 3.04, respectively. Besides, RSD values of four indices of some random samples were all very low. In conclusion, tobacco flavor and fragrance indices could be determined rapidly and simultaneously without any damage by FT-NIR, which would achieve on-line determination and real-time control of products.