Adored for its ability to give us a jolt of energy on tap, 80% of the world’s population consumes caffeine in some way daily - but do we really know how it works?
As speciality coffee roasters, we at Dear Green have roasted coffee for the better part of two decades, and we like to think we know a thing or two about it! Join us as we look into the science, the history, the facts and the fiction of caffeine.
What is caffeine
Caffeine is a white (slightly bitter-tasting) crystalline purine, methylxanthine alkaloid, which features a ring system of three methyl groups and two carbonyl oxygen atoms (C₈H₁₀N₄) (obviously). Aside from that, it’s the world’s best-known and most-used psychoactive stimulant. Here it is in molecular form so you can put a name to a face!
How caffeine affects the body
In a nutshell, caffeine stimulates our central nervous system by blocking the brain’s adenosine receptors. This stops our brains from realising that we’re tired, allowing us to remain artificially alert.
Excessive consumption can lead to a diminished overall effect and a general dependence over time. If not carefully managed, this can lead to symptoms of caffeine withdrawal, including poor sleep and heightened general anxiety, while the body begins to crave more and more caffeine to feel ‘normal’.
On the other hand,, those who drink caffeine less frequently will experience more pronounced effects, but this may come at the cost of spikes of anxiety or ‘the jitters’.
How much caffeine is in coffee?
Now that we know how it affects the body, how much is actually in the cup you're currently holding?
Caffeine can vary from coffee to coffee depending on a number of factors that we’ll discuss further below, but, on average, one cup contains 100 mg of caffeine. Although the official recommended daily allowance for caffeine is 400mg per day in adults, consuming it is all about balance. Your response will be unique in relation to others and even yourself from one day to the next.
What factors can change the amount of caffeine in coffee?
Moving back to coffee, there’s plenty of conflicting information about which coffee contains the most caffeine, so what’s the real story?
Bean type
While Dear Green exclusively roasts Arabica coffee, Robusta coffee has seen increased popularity in recent years, thanks to its lower production costs, meaning you’re more likely than ever to see it in your typical high street flat white.
Because Robusta contains twice the caffeine, drinkers may experience a more pronounced stimulant effect. For this reason, you might notice a slightly different physical reaction to the coffee you drink, depending on where you get your coffee.
You can find out more about the distinctions between these beans in our introduction to speciality coffee blog.
Processing Method
Specific processing methods can also affect the presence of caffeine within the coffee. With a significant amount of caffeine found within the coffee cherry’s pulp, washing this off (as we would using the washed processing method) will result in a lower amount of caffeine vs natural processing.
However, in comparison to some of the other factors here, processing plays a comparatively minor role in altering caffeine content.
Roast
When coffee is roasted, it loses more and more of its weight the longer it’s roasted. Due to caffeine’s relatively stable nature at high temperatures, such as this, the caffeine content will remain relatively unchanged.
That being said, because light-roasted beans are slightly denser than dark-roasted beans, they will have a marginally higher caffeine content when measured volumetrically. This is something to be aware of when measuring by scoop rather than weight. For accuracy and consistency, we recommend measuring by weight with a good set of scales.
Brew Method
Brew methods can also significantly impact the caffeine content, primarily due to variations in extraction rates.
Espresso, despite its reputation only contains 60-80 mg of caffeine per cup, while percolation and immersion brewing methods, such as V60 and French press, allow for a higher amount of contact time between coffee and water, averaging 105 mg and 145mg respectively (Illy and Viani, 2004), resulting in a greater extraction of caffeine into the final brew.
Methods that use a finer grind size can also affect the overall caffeine content. In cases where smaller grounds are used, the water present in the brewing method can come into contact with a greater portion of the coffee’s surface, allowing for a higher extraction level and concentration of caffeine in the brew.
Is decaf coffee really caffeine-free?
The short answer is no - completely removing caffeine from coffee is impossible. However, for decaf coffee to be referred to as such, it must be at least 97% free of caffeine in the US, while the EU requires a more stringent 99.99% purity.
This level of caffeine removal makes drinking coffee at any time of the day perfectly acceptable for the majority of drinkers.
While there are several methods of coffee decaffeination, including the Swiss Water method, an immersion technique, and carbon dioxide separation, Dear Green’s current decaf uses an ethyl acetate solvent process to remove caffeine.
Where can caffeine be found outside of coffee?
Of course, coffee isn’t the only place you can find caffeine. Despite the drink’s dominance worldwide (and its comparative caffeine content in relation to its competitors), many contenders can produce similar effects while being more appealing to palates that don’t enjoy coffee’s distinct taste.
Just as caffeine naturally occurs in coffee, it can be found in several other commonly consumed foods and drinks. This includes natural sources such as tea, matcha and cacao/chocolate, as well as artificial sources such as energy drinks, soft drinks and caffeine pills.
That being said, caffeine levels among all these products can vary greatly, leading to misinformation about their contents. For example, in the case of tea, unbrewed tea contains approximately 3.5% caffeine, while coffee contains around 1.5% on average. When brewing coffee, however, far more is used by weight to brew a single cup than it is to make a cup of tea with a single tea bag, meaning that your cup of coffee will contain more caffeine than your cup of tea.
How long does caffeine stay in the body?
After consumption, caffeine typically remains in the body for several hours, with an additional half-life of approximately five hours. While a single cup of coffee can stay in your system for up to 12 hours, this duration will vary depending on factors such as age, genetics, body composition, medication, and pregnancy.
What to do if you’ve had too much caffeine
Whether you’re over or under the recommended RDA of caffeine, whatever your body recognises as ‘too much’ caffeine is unpleasant, and can leave you feeling dizzy and anxious due to an increased heart rate and blood pressure.
If you want to offset your caffeine consumption, there are a few quick and easy tricks to make you feel a little more normal when the jitters take hold! These include eating a balanced meal to slow absorption, going for a walk (or light jog) to mitigate feelings of excess energy, and practicing deep breathing to lower heart rate.
And just like that, you’re a caffeine expert! Got more questions? Check out our blog, or get in touch with our team directly.Sign up for the Dear Green newsletter to stay up to date with our latest news, and follow our journey on Instagram, Facebook, Bluesky & TikTok.
References
1. Rogers, P. J., & Heckman, M. (2024). Evaluation of the caffeine content in servings of popular coffees in terms of its safe intake — can we drink 3–5 cups of coffee per day, as experts advise? Nutrients, 16(23), 2385. https://doi.org/10.3390/nu16232385
2. Illy, A. & Viani, R., 2005. Espresso Coffee: The Science of Quality. Illustrated edition. Oxford: Academic Press.