Continued from yesterday’s post Some Facts On Caffeine Levels in Tea – Part 1
Teabag Tea Facts
- Ground tea (in a teabag) has more caffeine in the first steeping than loose tea because of the greater surface area.
- Loose tea has more caffeine in the second and third steepings than ground tea.
- Teabag agitation in water (such as repeated dunking) does increase the infusion speed.
- Teabag size and shape can have an effect on how much caffeine is in the infusion.
Comparisons Between Different Types of Tea
- When all other factors are the same, white teas (young leaves and buds) had some of the highest caffeine levels.
- When all other factors are the same, one study found that unfermented (green) tea had slightly higher caffeine levels than fermented (oolong) tea.
- Tea plant cultivars affect the amount of caffeine. Most black teas are from Assam cultivars whereas most green teas are from China cultivars. Assam cultivars have measurably more caffeine than China cultivars; therefore on average, the black teas we consume have more caffeine than green teas.
- When black tea steeped in boiling water (90 degrees C) was compared to green tea steeped in sub-boiling water (75 degrees C), the green tea had significantly lower caffeine levels. This result was even more pronounced when the first green tea steeping was discarded after one minute and the second steeping measured.
- All camellia sinensis tea tested as having higher caffeine levels than the South American tisane yerba mate, despite its reputation.
This is a very basic parsing of a rather large amount of information. Please do read through the studies below, they are quite fascinating! (A part of me still can’t believe that dunking a teabag repeatedly actually makes a measurable difference…)
Caffeine in Chiang Rai tea infusions: Effects of tea variety, type, leaf form, and infusion conditions
Tea preparation and its influence on methylxanthine concentration
Factors Affecting the Caffeine and Polyphenol Contents of Black and Green Tea Infusions
Caffeine in teas: levels, transference to infusion and estimated intake
Photo “Test tubes of tea” is copyright under Creative Commons Attribution-NonCommercial Generic License 2.0 to the photographer Ayman Itani and is being posted unaltered (source)