#biology #substance


caffeine content

Coffee contains caffeine.

Coffee can be brewed multiple way, and the corresponding caffeine dosages can vary consequently. An espresso and a cup of brew have a relatively similar amount of caffeine, which makes the espresso much more caffeine-dense. Caffeine is easier to assimilate in higher doses, which makes espresso more efficient[3].

Generally speaking coffee is the beverage that contains most caffeine[3], even compared to caffeine or energy drinks[3] like Red Bull[4].

brewing and care

Brewing is the extraction of caffeine and essential oils from the beans into water. Cold water does not extract any. 95/98c is optimum. Beyond these temperates, acidity increases wildly.

Brewing quality depends on quality of water, cleanliness of equipment, time since roasting and grinding. Quality of beans is only important if these are good. Equipment needs to be thoroughly washed to get rid of previous oils[3].

Re-heating coffee is destroying the essential oils and ruining the coffee.

Store coffee in air-tight container to prevent oxydizing, use glass which prevents contamination from one batch to the next.


Caffeine has multiple effects: stimulant of the nervous system, cardiac muscle, diuretic, and delays fatigue.

Fatigue and drowsiness is due to the accumulation of adenosine in the neuronal synapse. Caffeine delays the feeling of fatigue by binding to the adenosine receptors but not activating them{todo: reference}. Caffeine has a half life of between 3 and 7h, which means that its effects are halving every 3 to 7h, and can therefore be felt long after intake ceased.

Coffee is partially laxative for about 30% of the population. It's unclear what is the factor though, since decaf seems to have a higher response[1], and hot water also has response[2].

While over-consumption can have negative side-effects, there doesn't seem to be a correlation between caffeine intake and increase death[3].

While withdrawal from caffeine is engendering headaches, there is little proof to the efficacy of caffeine against headaches[3].


Drinking two to three cups of coffee a day is linked with a longer lifespan and lower risk of cardiovascular disease compared with avoiding coffee, according to new research. The findings applied to ground, instant and decaffeinated varieties.