Coffee is one bean with many possibilities. The big choice is how to brew it: espresso, filter, plunger, percolator, instant and more. Each method has unique equipment, time, temperature, pressure, coffee grind and water requirement.
Our choice of brewing method can be cultural, social, or practical. But how much do they really affect what’s in your cup?
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What is the strongest drink?
It depends. If we focus on caffeine concentration, on a milligram per milliliter (mg/mL) basis, espresso methods tend to be the most concentrated, capable of delivering up to 4.2 mg/mL. This is about three times higher than other methods such as mocha pot (a type of boiling percolator) and cold brewing at about 1.25 mg/mL. Drip and plunge methods (including French and Aeropress) are about half as much.
Espresso methods extract the most caffeine for several reasons. Using the finest grind means more contact between coffee and water. Espresso also uses pressure, pushing more compounds into the water. While other methods take longer to brew, this does not affect the caffeine. This is because caffeine is water soluble and easily extracted, so it is released at the very beginning of brewing.
But these comparisons are based on typical booty situations that are not typical consumption situations.
So while espresso gives you the most concentrated product, it comes in a smaller volume (only 18-30 ml) compared to much larger volumes for most other methods. These volumes vary by manufacturer, of course, but a recent Italian study identified a typical final serving for filter, percolator, and cold beer as 120 ml.
Based on this math, cold brew is actually the highest dose of caffeine per serving – almost 150mg – even more than the total 42-122mg found in finished espresso. Although cold brew uses cold water and a coarser grind, it is brewed with a high coffee to water ratio and additional beans are required for brewing. Of course, “standard servings” is a concept, not a reality – you can increase the number of servings and increase the volume of any coffee drink!
With coffee prices on the rise, you might also be interested in extraction efficiency – how much caffeine you get for every gram of coffee.
Interestingly, most of the methods are actually very similar. Espresso brewing methods vary, but yield an average of 10.5 mg per gram (mg/g) compared to 9.7–10.2 mg/g for most other methods. The only exception is the French press, which contains only 6.9 mg/g of caffeine.
“Strength” is more than just caffeine
The caffeine content explains only a small part of the strength of the coffee. Thousands of compounds are extracted, contributing to aroma, taste and function. Each of them has its own extraction scheme, and they can interact with each other, suppressing or enhancing the effects.
The oils responsible for crema — the thick brown “foam” on the surface of the drink — are also more easily extracted at high temperatures, pressures, and fine grinds (another potential win for espresso and moka). These methods also produce higher levels of dissolved solids, which means a less watery consistency, but again it all depends on how the end product is served and diluted.
To complicate matters further, the receptors that detect caffeine and other bitter compounds vary greatly from person to person due to genetics and training as a result of our normal exposure. This means that the same coffee samples can give different people different perceptions of their bitterness and strength.
There are also differences in how sensitive we are to the stimulant effects of caffeine. So, what we look for in a cup and what we get out of it depends on our own unique biology.
Is there a healthier drink?
Depending on the headline or day, coffee can be presented as beneficial or harmful. This is partly due to our optimistic bias (of course we want coffee to be good for us!), but may also be due to the difficulty of learning about products like coffee, where complexity of brewing methods and other variables are hard to capture.
Some studies have shown that the health effects of coffee depend on the type of drink. For example, filtered coffee has been associated with more positive cardiovascular outcomes in older adults.
This link may be a coincidence based on other coexisting habits, but there is some evidence that filtered coffee is healthier because coffee retains more diterpenes (a chemical found in coffee that may be linked to higher levels of bad cholesterol). filter, that is, less reaches the cup.
Each brewing method has its own characteristics and input data. This gives each product a unique flavor profile, texture, appearance and bioactive compounds. While the complexity is real and interesting, ultimately how to brew is a personal choice.
Different information and situations lead to different choices for different people and on different days. Not every food and drink selection needs optimization!
Emma Beckett, Senior Lecturer (Food Science and Human Nutrition), School of Environmental and Life Sciences, Newcastle University
This article is republished from The Conversation under a Creative Commons license. Read the original article.