Over the past few months, since getting my Gaggia Classic, I've made at least 4 double espressos every day, most of which have then gone into a latte in a bid to (a) give my wife something to smile about, and (b) improve my milk steaming and latte art abilities.
Recently I hit a stumbling block when I bought some fairly 'challenging' beans from a local roaster and just couldn't get a good espresso shot from them. After posting on coffeeforums and changing brew parameters I managed to get an acceptable extraction, but it got me thinking that I still have a lot to learn, and it's easy for a beginner like myself to fall into the trap of think he's cracked espresso when really all he's done is gain a fairly superficial skills in the mechanics of pulling a shot, without truly understanding the nature of coffee extraction. Why would the latter be important? Because (amongst other things) if your understanding of the science behind the shot is limited then you won't know what to do when something doesn't go according to plan, as I found out with my challenging beans.
- Should you updose?
- Downdose?
- Grind finer/coarser?
- Is your brew temperature too hot/cold?
- Are you over-extracting? Under-extracting?
- What do over- and under-extracting even really mean? Are you sure you know?
Do you even know what questions to ask yourself? I realised that I didn't.
On reflection, I think it's part of the natural evolution of a barista-in-training. I'd liken it to someone learning to ski. You simply can't be taught how to ski off piste the first day you put the skis on. You have to learn the snow plough first. Eventually you have to unlearn the snow plough, but it's a good place to start. There's a sequence of events that you take to learn. It's not the only way, but it works.
Similarly with learning to extract espresso. At first you're taught basic parameters such as:
- 7g for single shot
- 14g for double
- Tamp with 30 lb of pressure
- Extraction should complete within 18-23 seconds of the first drops appearing
- A single shot is 1 oz
- A double is 2 oz
Then as you develop, you get involved in discussions with other baristas. You learn new things, some of which contradict what you've already learned, such as:
- Most people don't pull singles
- Most people use most than 14g for their double shots
- Many people talk about the perfect '30 second extraction', counting from when they start the brew rather than from first drops
- Others don't use time to dictate when the shot should stop. They rely on visual cues, like watching for when the flow starts to turn blonde.
So you absorb all of this, which I did, and you notice improvement in your shots. But is it enough? I've found that I'm still keen to learn more.
So I've recently read a few more things that have really piqued my curiosity. Gentlemen such as Andy Schecter (who's every written word has hugely impressed me) and James Hoffman were talking about Espresso Brew Ratios way back in 2006. One of the key tenets of using brew ratios is that due to the existence of crema you can't accurately see how much espresso has been yielded by an extraction. Using fluid ounces, a unit of volume, is fundamentally flawed because the volume varies depending upon bean freshness and crema production. Using grammes to measure both pre- and post- extraction is arguably a better approach.
Here are some links on this subject:
Home-Barista forum discussion
James Hoffman's Blog
http://marco.ie/uberproject/?p=602
So I'm keen to start weighing my espresso shots. This isn't something I'd envisage doing if working in a cafe environment (but you never know!), but I think it will help advance my understanding enornously.
For a start, just by reading the above I've learned a few new phrases. I'm finding that these definitions, like many things in this arena, are subject to debate, but here they are:
TDS (Total Dissolved Solids) is a measure of the amount of solids that pass into the resulting espresso from the ground coffee beans.
Extraction Yield is defined as "mass of coffee solids in the beverage divided by mass of original dry coffee dose".
I've also established that presumably there is a 'preferred' TDS value for espresso, based upon empirical research and experimentation over the years, possibly by the SCAA.
Also that the SCAA 'preferred' extraction yield is 18-22%.
Now we're getting scientific, which is definitely helping me. I know that ultimately it's all about personal taste, and no scientific formula can guarantee a good expresso, but I reckon that understanding these elements of the equation can only help.
So what's next? Well, in my view I still only have a fairly superficial understanding so I need to keep reading and experimenting. My plans include:
1. Today I've received "Espresso Coffee: Professional Techniques" by David Schomer. I think it will give me more than a solid foundation in espresso, if 3 months of reading forums has not already achieved that.
2. I'm going to run a series of tests, pulling espresso with constant and varying parameters for pre/post shot weight, extraction time, resulting brew ratio, and in the absence of having a refractometer to measure Extraction Yield and TDS I'm just going to use my gob, and taste it. I hope I'll get several things out of this. An improved coffee palate for one, a better understanding of the extraction process, and an opinion of where my own preferences lie with regards to espresso brew ratios. In 2009 James Hoffman ran a poll of just under 100 people to capture details of their espresso preferences.
If the average preferred brew ratio is 53%, where do I sit?
Anyway, time to stop gassing and get on with it! Thanks for reading today's hefty post!!
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