Caffeine content of brewed teas.
Caffeine is the world's most popular drug and can be found in many beverages including tea. It is a psychostimulant that is widely used to enhance alertness and improve performance. This study was conducted to determine the concentration of caffeine in 20 assorted commercial tea products. The teas were brewed under a variety of conditions including different serving sizes and steep-times. Caffeine was isolated from the teas with liquid-liquid extraction and quantitated by gas chromatography with nitrogen-phosphorus detection. Caffeine concentrations in white, green, and black teas ranged from 14 to 61 mg per serving (6 or 8 oz) with no observable trend in caffeine concentration due to the variety of tea. The decaffeinated teas contained less than 12 mg of caffeine per serving, and caffeine was not detected in the herbal tea varieties. In most instances, the 6- and 8-oz serving sizes contained similar caffeine concentrations per ounce, but the steep-time affected the caffeine concentration of the tea. These findings indicate that most brewed teas contain less caffeine per serving than brewed coffee.
Chin
Jenna M
JM
Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, P.O. Box 100275, Gainesville, Florida 32610-0275, USA.
Merves
Michele L
ML
Goldberger
Bruce A
BA
Sampson-Cone
Angela
A
Cone
Edward J
EJ
D002110:Caffeine / Q000032:analysis*; D002849:Chromatography, Gas; D013662:Tea / Q000737:chemistry*
D013662:Tea; D002110:Caffeine