Laser-induced fluorescence monitoring of Chinese longjing tea

Abstract

Laser-induced fluorescence (LIF) spectra of a bush and numerous branches of Chinese Longjing tea were investigated remotely with lidar techniques. The intensity ratio between the far red fluorescence (FRF) and red fluorescence (RF) due to the chlorophyll content of the tea branches were analyzed to study the growth conditions in different villages around Hangzhou, China. Dried Longjing tea leaves were also measured by LIF techniques in the laboratory. A chemometric method based on singular value decomposition (SVD) and linear discriminant analysis (LDA) was used to evaluate the tea qualities of the dried tea leaves.

LED-induced fluorescence system for tea classification and quality assessment

“…7. Comparing with the negative results for the dried Longjing tea leaves using 355 nm excitation wavelength presented in Mei et al (2012b), the grades assessed through the LED fluorescence system agree well with grades of tea samples decided by experts, with a correlation factor of 0.99 and 0.98 for dried tea leaves and liquid tea samples, respectively. The multi LEDs obviously provide more possibility for quality evaluation.…”