Back when I used to live and die with coffee (no... seriously), I spent a lot of time writing for this blog, posting on coffee sites, writing for Barista Magazine, etc.
The other day someone asked me what the best thing I ever wrote was. My first choice was my last article for Barista Magazine - my piece on CoE Brazil and Espresso. As I have been told, however, that this is "my Valis"... I figure I might not have great perspective on it.
So I remembered that I was asked (on Home Barista.com) "how do you explore the extraction space" with espresso? And I remembered that my response was seen by folks as pretty good. So I went back and re-read it. And, to be honest, I thought it was pretty good indeed. It seems to have become buried in that site - so I figure I'll re-post it here from it's original thread.
To be honest, it's largely trial and error leading to some vague understandings of general rules. I wish I were better at it or it were more scientific.
I tend to follow a pretty clear process and will happily describe this if it will help.
If I have a new coffee I tend to always start with the LM ridged double basket and a target extraction volume of between 1.75 and 2.0 oz.
First I'll establish a brew temp starting point.
I'll evaluate the coffee for two characteristics. First - roast degree and second - bean composition.
With the former, I tend to make some quick rough decisions. If the roast is light, I tend to start with a baseline temp of 202F. If medium, I will stick with 200F. If dark, I'll drop it down to 197F.
Now... I'll also adjust this based on the bean composition. If, for example, I'm working with high-grown washed arabica I'm going to reduce the brew temp. If I'm working with aged or monsooned coffees I will up the brew temp (both from the baseline above).
So a light roasted coffee with monsooned beans will move up to 203F as a starting point.
Once I have a temp starting point I'll establish a dose starting point.
For this I'll look at two aspects - the bean composition again and then the "signature taste."
If the coffee has a lot of naturals or pulped naturals I'll go with a lighter dose. If the coffee is mostly high-grown arabica I'll up the dose.
So, for example, with the Terroir Daterra Reserve I'd go with a 17.5 gram dose. But with the Stumptown Hairbender I'd go with a 20 gram dose.
The "signature taste" is a harder one and requires some knowledge of the roaster. Is the person roasting this coffee a fan of low acidity espresso? Are they a "chocolate bomb" aficionado? If you know what they like out of their espresso you can do minor adjustments to your dose. So, for example, based on this I would actually drop the Terroir Daterra down to a 17 gram dose but would up the Stumptown Hairbender to a 20.5 gram dose.
Once I've got temp and dose I'll start experimenting.
I always start by re-evaluating temp. So I'll pull a shot and evaluate it for brew temp. Is it alkaloid? Is it thin? Is it sour? Astringent? Based on the taste, I will alter the temp by small degrees to find the sweet spot.
Once I've found what I feel is the brew temp sweet spot, I'll start working on dose.
The way I tend to do this is focus on two things. First - clarity of flavour and second - roundness and balance.
If the cup is "muddied" I'll reduce the dose. If the cup isn't fully developed and sweet and rich I'll up the dose.
With many coffees this will get me to the point where I'll have a cup profile I really like.
But there are exceptions. There are times when I won't be able to get to where I want to be with just these factors.
It's usually only at this point that I start looking at changes to extraction volume and basket size.
For example, I've found that some lighter roasted delicate coffees tend to end up poorly developed no matter what I do - especially when they are pulped naturals. But if I then swap to a triple basket and deliberately down-dose (19 grams) I "open up" the coffee and it becomes more defined and clear. Or with monsooned coffee I find that the only way I can get the desired sweetness without getting a "wet cardboard" aftertaste is by going with a triple basket, normal dose and then pulling a ristretto shot.
A lot of the time I'll find a "sweet spot" that I like but then start wondering about what a coffee would taste like when pulled differently.
To be honest... I'm incredibly lucky. Most of the coffee I experiment with is free to me. If I were roasting my own, especially in small batches, I don't know if my approach would work at all. And if I were paying retail... I don't know if I could force myself to throw away so much money.