Simultaneous determination of six main types of lipid-soluble pigments in green tea by visible and near-infrared spectroscopy

Lipid-soluble pigments make great contributions to the color of green tea. This study aimed to rapidly and simultaneously measure six main types of lipid-soluble pigments in green tea by using the visible and near-infrared (Vis-NIR) spectroscopy. A total of 135 tea samples with five kinds and three grades were collected for spectral scanning and color measurement, and their lipid-soluble pigments contents were measured by high performance liquid chromatography. It can be found that tea color was closely related to the six pigments. And there were significant differences in lipid-soluble pigments contents among these kinds and grades. Finally, quantitative determination models of the six pigments obtained excellent results with Rp2 of 0.975, 0.973, 0.993, 0.919, 0.962 and 0.965 respectively based on multiple linear regression with the characteristic wavelengths. These results demonstrated that the Vis-NIR spectroscopy combined with chemometrics is a powerful tool for rapid determination of lipid-soluble pigments in green tea.