dirty == chocolate?

So I've been running a little experiment over here.

You see - due to the combination of thanksgiving chaos and work chaos I screwed up recently and didn't backflush my machine for a couple of days. Those who know me have heard endlessly about the importance of a clean machine - and about how I backflush with detergent daily. In this case, however, I didn't have the chance. Sure, I rinsed - but no full clean.

On the third day, I pulled a shot of Ecco espresso and got a very unusual flavour profile. The shot was incredibly chocolate-dominant. I realized that the shot tasted the way home baristas on the internet keep describing "comfort food espresso" tastes. Various folks have described espressos ranging from the Four Barrel to Stumptown to even Ecco in this manner. I never really got this profile and assumed that it was either due to different prep or just the subjectivity of taste.

Home baristas also seem to clean their machines rarely.

Hmm... I wondered... could there be a causal relationship here?

So I've been experimenting with a dirty machine. And the results are very interesting.

First of all, almost all the espressos I've tasted end up tasting similar. They mostly turn into chocolate dominant shots with very little clarity or separation of flavours. Fruit notes are preserved although often translated into darker (or dried) versions of the same flavour.

Secondly, while I think that in milk drinks this profile is often very nice - I feel like the uniqueness of the espressos is lost (the coffee is "dumbed down" in a sense). I could see how someone coming from a coffee background that is based on roast flavours might like this.

Third, the results are pretty much universal for blends. For single origin shots, however, the results seem to be more positive with some regions (Brazil and Ethiopia for example) and far less positive with others (in particular with more delicate central american coffees).

Finally, this seems to work best with lighter roasted coffees. Darker roasted coffees seem to "foul" the machine more quickly - yielding shots that taste dirty and "fish oil" nasty.

I think this is a good example of needing a similar context and perspective in order to share opinions. I know understand why a lot of home baristas describe some coffees the way they do. I understand why most home baristas feel cleaning daily is a waste of time. I even understand (a bit better) why some coffees are so prized by home baristas.

Personally, I'm glad to have the experiment over. I'm looking forward to a nice, transparent and clean coffee tomorrow.


Unknown said...

To me, the taste of a dirty machine is very particular, and tastes like nothing else. It is dirty machine taste, period. And it's impossible for me to get past; put simply, it ruins the shot.
And it doesn't matter what blend or SO goes through a dirty machine, it never has a positive result for any of them.
Home machines should be cleaned with detergent daily, and commercial establishments should be thoroughly back-flushing and swapping out cleaned screws and screens once an hour, no matter the volume.
There is nothing worse than the taste of a dirty espresso machine!

chris said...

I used to say the exact same thing.
And the reality is that, for me, I still believe it. I don't like muddy flavours. I don't like the slight rancid oil bite. I prize the taste from a clean machine. I think cleaning should be frequent and regular and thorough.

That doesn't mean I shouldn't try to understand those who disagree with me. I'm not that arrogant.

Just like learning to understand that many don't like "sour" coffee (and understanding the implications of what that means for a roaster), we need to understand that many don't clean their machines regularly - and we need to understand what that means in the cup.

Unknown said...

I take great joy in helping people understand what it is that they're experiencing in the cup (just as I enjoy having other food professionals walk me through tastings of their chosen food/drink), and in illustrating differences/variety of flavours in coffee for everyone. The general public is my favourite audience, and I will never tire of that part of my work in the specialty coffee industry.
And as part of that, I make a special point (and encourage every other coffee professional to do so, too) to drink all kinds of coffee at all kinds of establishments (including home set-ups). It is very very important that we understand how people experience coffee currently, how they brew at home, and how to possibly guide and broaden their coffee experiences.
This humility and context is absolutely essential for all coffee professionals, and is the foundation for avoiding the 'pretentious barista' syndrome... and therefore key to the cooperative and participatory approach that we should be taking as we strive to spread the word about quality coffee and suggest good ways to brew it.
I did not mean to second-guess your commitment to understanding this very same thing: we agree completely that we should be understanding how people currently taste/prepare their coffee. Of course! What I worry about with this post is that some people may equate the taste of 'chocolate' with 'dirty espresso machine'. When they are very different tastes (to me, at least), and one is positive while the other is quite negative.

James Hoffmann said...

Interesting. I think my initial thoughts were the same as Amber's - dirt is evil, distracting and a particular kind of unpleasantness.

I wonder if there is some distinction between the kind of build up we experience in a commercial setting, and the dirt built up from a few shots a day? You've experienced both - so it seems fair to ask.

Without that distinction I'd really be struggling to associate what I perceive as dirty with any kind of chocolate.

chris said...


I'm guessing there is a fine line indeed between the "chocolate" result and "rancid cod liver oil" and that in a bar environment that line is crossed so quickly that the odds of ever getting to taste is are very small indeed.

I've never tasted this on bar (where the flavours are overwhelmingly negative).

One important note: I would never suggest that a dirty machine results in better espresso. It always (to my taste) results in degraded coffee in the cup. It's just that it also skews the flavour profile towards chocolate (regardless of coffee or blend).

Daniel Stewart Mueller said...

I've experienced this chocolate situation at home moreso than on bar, but I'd often wondered if that wasn't my palate's predisposition to tasting chocolate in coffees.

What might be a good methodology of testing this?

Initial thoughts are to dial in a coffee, clean the machine and create a quick flavor profile. then, pull 10 or so shots and taste the 11th, creating another quick profile.

Then it's just a matter of comparing the two profiles.

Does this sound like it might work?

-Dan Mueller