Abstract

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). © 2010 Elsevier Ltd.

Author-supplied keywords

• Brewing
• L-Theanine
• Milk
• Preparation methods
• RP-HPLC (Reversed-phase high performance liquid chromatography)
• Sugar
• Tea
• γ-Glutamylethylamide

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• ISBN: 0308-8146
• PII: S0308814610011416
• PUI: 51103040
• ISSN: 03088146
• SCOPUS: 2-s2.0-78049420281
• DOI: 10.1016/j.foodchem.2010.08.071
• SGR: 78049420281

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