FTNIR Spectroscopic Method for Determination of Moisture Content in Green Tea Granules

The feasibility of measuring moisture content in green tea by Fourier transform near infrared (FTNIR) spectroscopic technique was investigated. Green tea granules samples with different moisture contents were scanned using FTNIR spectroscopy. The spectra were measured in diffused reflectance mode by keeping 4-5 g samples in small sample bottle. A partial least-square regression model was developed with vector normalization method in the near-infrared region (4,000-12,000 cm(-1) or 800-2,500 nm). The developed model was validated using cross-validation technique. Maximum coefficient of determination (r(2)) value of 0.997 was obtained for the calibration model developed. The developed method was used further for quantification of moisture content in fresh green tea samples, and the results were compared with other methods like gravimetric method and moisture analyzer. Results indicated that FTNIR spectroscopy could be used for rapid detection of moisture content in green tea granules without destruction of samples. The measurement will take only 5-10 s.