New Analytical Solution for Theanine Detection

Biochrom has developed a new analytical procedure for the food and drink industry using the Biochrom 30 Lithium High Performance Amino
Acid Analyser to analyse the theanine content in green tea leaves.

A molecule derived from the amino acid glutamine, theanine is typically found in tea (infusions of Camellia sinensis) and also in the basidiomycete mushroom Boletus badius.

The anine’s ability to enter the brain gives the molecule psychoactive properties that gives the molecule the capacity to reduce mental and physical stress, may produce feelings of relaxation, and improves cognition and mood when taken in combination with caffeine. The effects are believed to be caused by the ability of theanine to increase GABA production in the brain.

To analyse the theanine levels of finely ground green tea leaves the Biochrom 30 Lithium High Performance system is equipped with a 20cm x 4.6mm I.D LiHP column and a set of Lithium Citrate buffers to extract the free amino acid content from the tea leaves. Biochrom recommends that the extracts are deproteinised with sulphosalicylic acid solution containing Norleucine as the internal standard. The samples should be
filtered through a 0.22μm membrane. 40μL was injected onto the column.

A standard High Performance elution programme can be used with the instrument to quickly separate the theanine from any other amino acids present in the tea. The elute solution gives a high response when reacting with a Ninhydrin reagent and the analysis method also allows the identification of 20 other amino acids naturally present in tea in a single run.