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DOI: 10.1055/s-0032-1321208
Determination of theanin content in green tea samples – A challenge for NIR
The amount of tea produced worldwide surpassed 4.4 million tons in 2010.To handle such vast amounts fast analytical techniques are needed. The currently used HPLC provides a lot of information about the analysed sample, but requires sample preparation and the use of solvents. It would be desirable to have fast technique with little sample preparation at hand.
Here near infrared spectroscopy (NIR) could be the solution.
We developed a method for the determination of theanine content in dried green tea on the basis of 43 different samples including flavoured ones. Theanine is an unusual amino acid with important impact on esp green tea flavour, biological activity and quality. Using the partial least square algorithm, we obtained a coefficient of correlation of 78% compared to the HPLC reference method.
With NIR being well established in industrial analytical laboratories, we show that it also serves as a fast and cost effective method for the quality testing of green tea.