Seasonal Variation of L-Theanine Content in Tea: A Study on Darjeeling Black Tea

To date quality and selling price of a tea mainly depends on its flavour, taste and texture but not on its medicinal properties though a Chinese scientist in 780 AD suggested and acclaimed tea as a divine remedy and supreme gift of God for preserving mental tranquillity. Different studies have been showed that L-theanine is the key component of tea which can make us mentally calm, cool and relaxed. At the same time it can protect us from different ailments. There is a notion that L-theanine is present only in green teas, but that is not accurate. Both black and green teas have been found to contain the compound. However, the L-theanine content varies dramatically from tea to tea. Therefore, in this backdrop we aim at quantization of L-theanine in black tea prepared from five different tea clonal varieties, e.g. AV2, B777, HV39, B157 and P312 of all the four flushes. Our study highlighted that black tea of first flush (Spring flush) have highest L-theanine content (~1.3%) than other three flushes. It was also observed that among the five clonal varieties released for Darjeeling, B777 contain highest amount of L-theanine than other clones under study. Thus L-theanine content in tea along with other bioactive components can be considered as an index of tea quality and price determination in tea auction.