Brewing Revelations

The other day I had the chance to play with Malkoehnig EK43, read along to find out what happened.
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I’m playing around with the aeropress a lot and I’m trying to understand the brewing process better.


The issue is this:Coffee mess

When I’m making an aeropress usually my brewing temperature is quite low – around 87°C, at the championship was also this low, otherwise I tend to extract too much and the brew gets harsh and bitter. And I wonder why is that, when the recommended brewing temperature is above 90°C. In a recent conversation on the Room 409 Facebook page with Roger Wittwer, a Swiss coffee roaster, he pointed out at how many combinations there can be in a brew, which can lead to results, which are quite similar in taste and still not the same. The brew can be bitter, but that doesn’t automatically mean it’s over-extracted. It can be bitter and underdeveloped. I still have trouble identifying these differences.

Anyway, my theory when brewing with the aeropress is that I’m not getting an even extraction, because I don’t sift the coffee after I grind it. And more or less that’s why I’m using such a low temperature – the fines end up being over-extracted (or perfectly extracted) but the coarser grinds – under-extracted. Which somehow balances the percentage of the dissolved solubles and surprisingly sometimes tastes deceivingly delicious. This is not good if you want to reach some level of consistency though, because it’s again depending on a lot of factors and the damn coffee fines are just making the picture even more difficult to visualize. I’m open for discussion and will be happy to hear/read more opinions on the topic!

I started sifting, because my grinder is really good at making a lot of fines (it’s still the Porlex Mini) and everything else I kept the same. My observations are that:

  •  The pressing is easier and lasts shorter than before
  • The brew is quick, clean and very boring – underextracted

Now I have two some options:

  • Go up with the temperature
  • Make the brewing time longer
  • Make the grind finer (and sift again)

Now come and tell me coffee brewing is boring 😀


Yesterday I had a practice session at Stoll…actually since I bought the aeropress last week I haven’t stopped brewing. First, to get the hang of it, cause you know, it kind of matters which side of the aeropress points to the ceiling (and I obviously have a talent for embarrassing myself), then to develop a recipe for the competition. The good thing is my place gained the permanent smell of coffee, which I love, the not so good thing is that with all the new additions to my coffee laboratory my wallet got a bit…vacant. Oh, well, I don’t regret anything! I only miss a refractometer, but I can’t afford it and I’m not sure I need it at this stage. Especially if you can use someone else’s…But I find it a bit confusing and at times I feel lost, because when I brew something and when I measure it and the dissolved solids percentage turns out to be something different than what I’ve expected. I don’t know what should I expect, I can’t find the connection between the taste and the dissolved solids. Or it’s better to say I can’t taste the connection, because there obviously is one. Funny thing…I also doubt in myself, maybe I don’t do something right.

I totally got in love with my aeropress, I should give her (yes, it’s a “she”) a name, but I will leave this to Snehaa and Karla, when it comes to names there are the best! This brewing method is surely becoming my favorite, because the quantity is small and you have a perfect control over the brew. It’s ideal for experimenting. For now I’m using paper filters, but I would like to see the difference with the metal one…maybe next month. I’m also very pleasantly surprised how different coffee can taste in an aeropress. I think it makes it more fruity, crisp and fresh, but these are my observations.

As it turns out the Aeropress Championship will be held in the lovely Café Fruhling in Basel on the 22nd of March. All together there will be 27 participants, from which 9 will continue to semi-finals and 3 to finals. Everything will be tasted blindly, the judges won’t know who’s the brewer of the coffee they are tasting and also they won’t be measuring the TDS. They’ll just have to point to the cup they like most. Or should I say extraction they like most? Because the beans are going to be the same, so the judges are going to look for the perfect extraction. The finalist will go to the World Aeropress Championship in Rimini in July. As for me, I don’t have any expectations from the competition, it would be fun to brew coffee along with all these coffee people, I really look forward to it!

A post inspired by David Walsh’s lecture on NBC2012 regarding coffee extraction

Okay, so we talk about brewed coffee. There are rules, there are commonly agreed standards how to brew it and everybody brews it. How do we define our standards, what ideally extracted coffee is, what makes your cup of coffee good – we can indeed discuss much about it. These norms change as time goes, and people change their expectations from coffee as well. It’s a shame that most of the time coffee is being drunk for its functional qualities, than its taste, but this fact is slowly and surely changing. People are starting to realize this drink is not supposed to taste bad, but the opposite – it can have all different aromas and flavors, just like wine. But let’s get back to coffee.

So how did we shape these standards:

At the very beginning coffee was eaten, then wine was being made from it and only around the 11th century it started to become more like a drink. Then the invention of the coffee grinder came and soon enough in 1711 in Paris the practice of infusion began. Towards the end of 19th century in France the used ratio was a 100 grams of grounded coffee per liter. Meanwhile in the US you would drink coffee with coffee to water ratio as less as 14 grams per liter, you can imagine the difference in the taste, right? During WWII the development of the brew stops almost completely, except that the common recipes changed and the amount of used coffee per liter in the US doubled. After the war the Coffee Brewing Institute was formed and it started publishing a lot of research in this area. Also there was one study by the Midwest Research Institute that said region of optimal taste is between 18% and 22% extraction and since then this information was adopted from every coffee association.

And this was confirmed from the quite recent Gold Cup Research, part of the Gold Cup Programme launched by the Specialty Coffee Association of Europe. However, this range of optimal taste is not that tight, 48% of the participants selected their most liked coffee with extraction rate out of this bounds. So when we talk about preferences the picture gets bigger, right? There are not set boundaries of which you can like and which you cannot, this studies just show us that the peak of preferences is between 18% and 22% of extraction. But still, I believe that everyone should know the “standards” and only after that should be able to say what one’s preferences are.

For me, I enjoy playing with the variables when brewing. It’s interesting how the taste changes when for example you do a stronger brew, but you don’t let it extract for long, or change the grind, or even the water. I have to admit that as a mad scientist, I’ve had terrible experimenting sessions and sometimes the concoction has not been so pleasant to drink, but hey, that’s how you get to know coffee better. I like finding these differences, because it makes me more knowledgeable about the brew. And the good thing is that there’s always more to discover!

The Gold Cup Research is part of the Gold Cup Programme launched by the Specialty Coffee Association of Europe (SCAE). The goal of this programme is to improve the standard of filter coffee consumed in the marketplace, that’s why in 2010 the SCAE embarked on a study to determine the

European Extraction Preferences in Brewed Coffee

The last published data of this kind was in 1960’s by the Coffee Brewing Centre in the USA and it indicated ideal coffee extraction is when between 18% and 22%  of ground coffee is dissolved in hot water. This specification was adopted by many coffee associations and remained the same for more than 50 years. Now thanks to the carried out research by the SCAE we can see how accurate is the old specification nowadays.

The experiment itself was conducted in four European cities – Dublin, Maastricht, Cologne and Milan with 641 people involved. Each one of the participants was given to blindly taste five samples of coffee, each having a different extraction yield – 16%, 18%, 20%, 22% and 24%. The consistency of the taste for each tasting session was ensured by the use of freshly ground coffee – washed single origin Arabica – and an automatic batch coffee brewer. There were also many other regulations concerning the water, the grinders and the brewers which were providing constant delivery at each tasting session.

The combined results confirmed as remaining valid the study published by the Coffee Brewing Centre more than 50 years ago – 62% of all participants liked extraction ranges 18-22%. However the bell curve around this range is not as tight as expected, many of the partakers selected as most liked an extraction rate out of this bounds. The fact is that preferences don’t start and stop at 18% and 22%, but rather meet the majority of preferences within this range.