Recent interest into the possible benefits of L-theanine found in tea has raised the issue that there are few data available on amounts of L-theanine contained in cups of commercially-available teas, prepared by a standard method. HPLC along with a standard method of preparing tea was employed here to determine amounts of l-theanine in cups of tea and the effects that various preparation factors have on amounts of L-theanine extracted. Brewing time was found to be a major determinant of the amount of l-theanine extracted, while the addition of small amounts of milk and sugar made no significant difference. High levels of milk resulted in a marked lowering of the level of detectable L-theanine. Contrary to previous research, a standard (200 ml) cup of black tea was found to contain the most L-theanine (24.2 +/- 5.7 mg) while a cup of green tea contained the least (7.9 +/- 3.8 mg). (C) 2010 Elsevier Ltd All rights reserved.
- Brain and Behaviour
- Nutrition and Behaviour