A Coffee Blog

Annoying Espresso Myths

What is espresso, what should it be, how should it be made and consumed

We’ve decided to debunk some real-life espresso myths that are so common they annoy the hell out of us.

Many mass consumers believe in them, especially those who are not quite aware of what espresso is, what it should be, and how it should be made and consumed. So, let’s get to work!

Myth 1: You can make espresso without an espresso machine

In a word: no. In other words: no you can’t. Espresso, by definition since 1946 or 1947, is a concentrated drink made by applying very high pressure (much higher than steam alone can achieve!) to force water through a finely ground layer of ground coffee.

Let’s explain what modern espresso is. Nowadays, espresso is a drink made by the method of passing liquid under high pressure, using 7-10 grams of finely ground coffee per cup (15-30ml). 

Espresso is made with water heated to 90.5-96.1C, which is then forced through the layer of finely ground coffee under pressure reaching 9BAR, 135PSI or 930Kpa, with a tolerance of about 5-10% of the pressure.

The time from liquid to ready is approximately 20-30 seconds, not including any time before the pressurized water flows (or lower pressure “finish” time). 

The raw material can be from a single farm/type of coffee or a blend, but must be ground to an average size of 325 microns (±50um), and pressed into a disc form in a filter strainer. 

The resulting liquid must contain a) foam, b) almost completely opaque liquid, c) be 15-30ml per glass and d) be served at a temperature of 68C, plus or minus 5C.

There are those who will disagree with the criteria defined above or believe that there should be more freedom for variation, but we are confident that most will agree that this definition is the most widely accepted at the moment.

Let’s then move on to coffee machines that are not espresso machines or devices. The inventor of the Aeropress claims that his product makes espresso, but that simply isn’t true. The same goes for the $59 Krups and Salton “espresso machines” you see everywhere with a lever on top for a steam jet.

And they are not espresso machines (regardless of what the packaging says).

“The Cubans”? They are generally not espresso machines, again using the definition of espresso that has been around for about 70 years now. There are some stovetop coffee makers that use serious engineering to create “almost espresso” (“The Little Guy” is a similar device, achieving up to 6-7BAR pressure), but all Bialetti coffee makers achieve no more than 1.5BAR pressure and they make very lightly concentrated coffee, not real espresso.

To make espresso, you need an espresso machine designed specifically for that purpose, but that doesn’t necessarily mean an electric one. 

There are manual, non-electric machines that make modern espresso, including the Presso, ROK, Handpresso, and the sadly defunct Mypressi. Naturally, you need a method of heating the water, but even portable camp heaters are suitable for this.

You also don’t need a machine with an electric pump: machines like the La Pavoni Europicolla or the Elektra Micro Casa a Leva make great modern espresso via a lever (or in some cases a lever-driven spring). And, of course, there are many pump machines. 

All kinds of pumps – vibrating, rotary, even the latest fashion, variable speed pumps.

Speaking of pumps, let’s address one additional myth for a moment. You will often see cheap espresso machines advertised as providing 15, 16, and 18BAR pressure. Often with an exclamation after that marketing claim.

That’s bullshit, and it’s almost a guaranteed sign that the machine is made with cheap and poorly engineered parts. Let’s explain why in more detail.

Espresso is made at 9BAR pressure. 

Machines sold with bold marketing claims of 15 or 18BAR pressure wrongly convince customers that the higher the pressure, the better the espresso (hint: it’s not). Second, they still brew the coffee at 9BAR (roughly – pretty roughly). Why? Because there is a limiting valve or device inside the machine that takes the 15/16/18BAR pressure received from the built-in pump and limits it to 9BAR.

Why do these cheap machines brag about high pressure? Because they use very cheap vibrating diaphragm pumps – and put in very cheap internal connections, pipes, valves and connectors accordingly.

Cheap pumps lead to pressure differences, so if they are “set” at 9BAR at the factory, they give 6 to 12BAR when shot – and so are sometimes engineered to give 15-18BAR pressure.

Second, due to the cheap design of the inner tubes, pressure is lost on the way from the pump to the thermoblock; in some machines, entire 3BAR pressure is lost due to poor internal design and materials.

More expensive machines have better engineered and designed pumps providing close-to-spec pressure.

Even more expensive machines use rotary pumps, which are not only better at providing pressurized water but can be adjusted to give more or less pressure. Cheap machines do not have such capabilities, so they do what they can, bragging (unnecessarily) about their ultra-high pressure. We give you this debunked myth as a bonus.

Myth 2: Medium roast coffee has more caffeine than a dark roast

All coffee of a particular variety and type has roughly the same amount of caffeine, based on the caffeine content of each roasted bean, no matter how light or dark the roast is. 

But when you measure ground coffee in grams (rather than individual beans), the darker the roast, the more caffeine there is in each gram of ground coffee. How so? This has to do with the processes green coffee goes through when it is roasted.

When you roast coffee, literally thousands of tiny changes take place inside the coffee bean. Things burn (char); others change their state of matter (from solid to liquid and gas). Things (mostly gases) are released. Various chemicals in the grain are converted into other substances.

One chemical in green coffee doesn’t change much during the roasting process—and that’s the caffeine component. Caffeine is one of the more stable components in coffee, not changing much during roasting. Roasted coffee beans contain the same amount of caffeine as green beans.

However, other things in the coffee bean change dramatically during roasting.

This is why it loses between 10 and 25% of its weight during roasting, depending on how dark it is roasted: the darker the coffee is roasted, the greater the weight loss from the bean. And this is precisely the reason why dark roasted coffee beans give more caffeine than ground coffee.

We explain in more detail: if you take two coffee beans identical in size and weight as “green” (before roasting) and roast one medium (City) and the other dark (French), you can still extract 100% of the caffeine in each bean, and you have almost the same content of it in both beans (the French version may be 0.1mg less!). But a dark-roasted bean weighs about 10% less than a medium-roasted one, because of the more serious reduction in weight with darker roasting.

So if you want 100 grams of ground coffee, you’ll use (roughly) 10% more actual beans than the dark roast to get the same weight. Which – logically – gives (approximately) 10% more caffeine in 100g of dark roasted ground coffee compared to the lighter one. 

It is important to note that the darker the roast, the higher the percentage of caffeine in each bean (compared to all the other components in it). This leads to another side myth: some people believe that the darker the coffee is roasted, the more caffeine is created by the roasting process! As you can probably guess, roasting does not create caffeine. However, it lingers longer than other ingredients in the roasting bean, so its percentage in coffee increases.

So – dark roast ground coffee gives more caffeine than medium roast because it lingers longer in the roasting process when many other ingredients are lost.

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