Caffeine Content in Oolong Teas.
What is caffeine? Caffeine is a natural stimulant most commonly found in tea, coffee and cocoa plants. It stimulates your Central Nervous System (CNS for short) to keep you alert and prevent the onset of tiredness. Once consumed, caffeine gets absorbed into your gut and travels through your bloodstream to the liver. In the liver, the caffeine gets broken down into compounds that can affect various organs, mainly your brain.
Caffeine functions by blocking adenosine receptors in your brain so that adenosine neurotransmitters can not be released into your bloodstream. Adenosine is responsible for making you more relaxed and tired as the day passes by. Caffeine also triggers higher blood adrenaline levels and neurotransmitters such as dopamine and epinephrine. All of these factors contribute to an elevated state of arousal, alertness and focus. In sum, consuming moderate amounts of caffeine each day has been proven to have various health benefits such as increased alertness and focus and protecting against dementia, Alzheimer’s disease, metabolic syndrome, and non-alcoholic fatty liver disease, etc.
Any tea made from the tea plant, Camellia Sinensis, contains caffeine but a few factors determine whether the caffeine amount would be higher or lower.
Cultivation altitude: The caffeine content in tealeaves depend on how much sun exposure the tea plant gets. The more sunlight that a tea plant gets, such as certain types of oolongs or black teas grown at lower elevations, the caffeine content will be relatively higher than tea plants that get shorter days with less sunlight, such as high mountain oolongs. At higher altitudes, sunlight is often covered up by layers of mist and fog. This creates higher humidity which limits the amount of caffeine that tea plants can absorb, which explains why drinking high mountain oolongs (Dayuling, Lishan, Shanlinxi) is a healthier option.
Season of harvest: Winter and spring harvested teas have relatively shorter days of sunlight compared to summer and autumn teas. In general, winter and spring teas have lower caffeine.
Oxidation level: The amount of exposure to air during the tea-making renders a tea more (Eastern Beauty Oolong) or less (High Mountain Oolongs) oxidized. The higher the oxidation level, the more caffeine the tea contains.
Roasting level: Many people mistaken that the stronger a tea smells, the higher the caffeine content it contains. This is a myth proven wrong. The truth is actually the opposite- during the tea-making process, roasting at high temperatures would encourage the solvency of caffeine molecules, which evaporates with water during the roasting process. The darker the teas are roasted, the less caffeine it contains (eg. Dongding, Tieguanyin).
Brewing method: Using higher water temperature to brew teas would release more caffeine into your teas. In order to limit that, quick rinse and pours will be a better way than steeping your teas for longer times. Therefore, if you are drinking your oolong tea at night, we suggest that you brew your tea at lower temperatures or steep for shorter times as this will lower the concentration of caffeine. Cold brews are also a good way to go.
Looseleaf vs teabags: Looseleaf teas generally have less caffeine than most bagged teas that use broken leaves or crumbs. Since smaller pieces of tea crumbs have more surface area to be exposed to air and the hot water you brew your tea in, they will release more caffeine into your tea.
For anyone who is sensitive to caffeine, we suggest you prefer:
High mountain oolongs over lowland teas
Spring and winter harvests over summer and autumn teas
Whole looseleaf tea over broken-leafed or powdered tea
More roasted tea over less roasted tea
Less oxidized tea over more oxidized tea
brewing teas at cooler temperatures over hot
steeping teas for shorter times over longer times
*For pregnant or nursing women, we suggest that you hold off from drinking any caffeinated beverages at all.
