Thursday, 12 May 2011

More on the hunt for The Perfect Espresso

Following on from my last post, I’ve spent two or three days actively working on finding the best combination of parameters to produce as close to the perfect espresso as I’m capable of right now (notwithstanding various limitations outside my control).  The perfect espresso will always be a subjective thing, so my aim was to find the settings that suit my own palate.  In essence, I’m looking for the ‘brew recipe’ that works for me with the beans and equipment I’m using.

Before I explain more, I’ll just jump forward and say that this little experiment has yielded a huge amount of learning for me, someone relatively new to espresso.  I now know more about the type of espresso shot I like, how to make it, how to taste espresso, how to identify and describe what I’m tasting, and a few things that I now need to do next.  I’d recommend anyone who wants to improve their espresso to go through this simple process. As it involved mulling over your thoughts on the espresso shot, I’d sum the process up with the catchy phrase “Don’t just drink it, think it.”  Ahem...sorry about that bit!

OK, so, I wanted to make use of brew ratio (aka brewing ratio), which is a measure of the amount of liquid espresso produced in relation to the dry beans used. For example, if you use 14g of beans and end up with 28g of espresso, your brew ratio is 50% (also sometimes shown as 1:2).  Andy Schecter started an interesting post (see here) on Home Barista about it in 2006, and one of its proponents is James Hoffman (World Barista Champion).

As mentioned above, this involved weighing the amount of coffee before and after extraction.  Using weight (g) to measure the amount of espresso produces is arguably a more accurate approach than using fluid ounces (oz), because crema makes the true volume in oz very difficult to measure.  Therefore, rather than... or indeed as well as... talking about a 2oz shot, it can be more useful to use terms like a 30g shot, and a 65% brew ratio. 

It isn’t a new approach, but as Andy alludes to in his post it seems that many of us are reluctant to make the switch from using oz to using weight and brew ratios.  Maybe we feel comfortable with what we know, and see no reason to change.  My own feeling is that brew ratios provide the key to another door on the quest for the perfect espresso. It’s up to the individual to decide how many keys they want to collect, and how many doors they wish to open.

It took me only 9 shots, spread over 3 days, to identify the parameters that I like best.  I had my laptop open next to the espresso machine, and after each shot I scored the espresso based upon flavour and mouthfeel, and made comments and suggestions for how I might make improvements in the next shot – i.e. changes to parameters – in an effort to home in on the ‘sweet spot’.  A screenshot of the Excel file I used record the findings and calculate the brew ratio is shown below.  Each row represents a different shot and my findings/comments.

As are many parameters in making espresso, and changing any parameter will have an effect on the other parameters, there is no single correct approach.  But here is the one I followed.

Constants, limitations and assumptions:
1. Initially, try to keep all the parameters fairly constant except one – pre-grind dose weight.  As you get towards the latter stages of the process, you can start refining other parameters one at a time.

2. I used the same bag of espresso blend beans throughout, and of course if I use different beans in future I would expect the parameters to change.

3. I am currently unable to measure or accurately control brew temperature with my Gaggia Classic.  I therefore attempt to ‘temperature surf’, to provide a degree of temperature stability throughout the brewing process.

4. I do not have large enough scales to measure the weight of grinds in the portafilter before extraction.  I therefore base my pre-extraction weight upon the weight of the pre-ground beans.  As each bean tends to weigh approximately 0.8-0.12g, and I do not expect to lose more than 1 bean in the grinding process, I assume this approach is accurate enough for my purposes.

1.       Select an initial brew time, and keep that constant for now.  All extractions should be stopped on (for example) 24 seconds.  There will be a chance to adjust this later.
2.       Select a grind and keep it constant for now. Again, refinements will be made in due course, but by keeping this parameter constant you are able to work on refining the shot using other variable parameters.
3.       Select a range of Pre-Grind dose weights.  I chose 14g to 20g.  You are going to start with the lowest dose for your first shot, and move up the scale.  Dose is your primary variable parameter, at least initially.
4.       Weigh, Grind, Dose, Distribute and Tamp your first shot.
5.       Fit the portafilter into the grouphead and place scales on the drip tray. Put a shot glass on the scales and tare them to zero.
6.       Start the extraction. Begin your timer. 
7.       As the shot pours, watch it.  Notice how fast it extracts. Is the flow diameter thin or thick.  Is there any blonding, and if so when does it occur? This info can all be useful in your tasting notes, and inform your ‘suggestions for improvements’ in the next shot.
8.       Stop the shot at your target time.  Give the shot a few seconds to let the weight stabilise.  I take the glass and scales off the drip tray after about 3 seconds, and give them another 3 on the table before noting down the weight.
9.       Time to start assessing the shot.  First, it is worthwhile noting what you think is the approximate volume in oz, just to tie the data in with the way you previously measured it.
10.   How does it look? How does it taste? What is the mouthfeel like?
(a) Here is a good link for non-coffee-geeks on how to taste espresso. It's worth taking the time, if you're not used to thinking about and describing what you're tasting, which I'm not!
(b) The Coffee Tasting Flavour Wheel.  Have this open on your computer.  This part really involves thinking, not just drinking.  Look at the wheel and see if you can identify any of the tastes/aromas.  My palate is terrible and I’ve never before been able to pick out things like sweetness, or acidity, or tartness, but going through this process has been a revelation and as you can see from my comments, I’ve started being able to pick out some of these.

Write down your scores (out of 10) and your tasting comments. 
Do you like this shot.  If so, notice the brew ratio. Are you tending towards a preference for Ristretto (100% brew ratio), Normale espresso (approx 40%-60%), or Lungo (33%). It’s good to know your own tastes.
Reflect upon your comments.  Look at the data.  Try to understand why it is something may be the way it is. For example, look at my 16g shot.  I saw ‘Tart’ on the flavour wheel, and also that it is part of the Sour range.  I’ve read that Sourness can come from low brew temperatures, so I made a note in the column called “suggestions for improvement” to try to improve my temperature surfing in the next shots.  I did so by flushing 2oz of water through the group head, 2 or 3 times, with a few seconds gap inbetween each burst, just before fitting the portafilter. 
11.   OK, time for the next shot incorporating one of your suggestions.  Don’t make lots of changes all at once. Remember, we’re trying to keep as many parameters constant as possible.  So, increase your dose from 14g to 15g, and if you are able to make other improvements without feeling like you’re significantly changing the balance of the brew parameters, do so.
NB: Really try not to change the grind setting in the early stages.  Changes in the dose will effect the flow rate of the shot, so you may find that a fast flow slows down as you updose.
12.   Go through this cycle a few times, increasing the dose each time.  Eventually you will get a feel for the pre-grind dose and brew ratio that is working best for your own palate. Now you can start to refine other parameters.  I recommend starting with time and leaving grind for now, unless it’s clear to you that the grind is just not right. So, if you find that the shot tastes great but there is just not enough of it, try changing the brew time from 24 seconds to 25 seconds and see how it tastes. Maybe this will result in a more bitter shot as more of the compounds from the bean are extracted.  If this is not to your liking, then stick to 24 seconds, but now you can try changing the grind.  Try making it coarser, to allow more water to flow through the grinds. Now pull shot and make your tasting notes. Not right for you? Perhaps you should actually have made the grind finer, allowing more solids from the bean to enter the espresso.  Change the grind, pull a shot, and make your comments.
13.   At the end of this process you should have identified one shot that scores higher than the others.  You may also have found out some of the limitations of your equipment or indeed your skills.  For example, I was unable to produce a shot that I liked greater than 25-28g (approx 1.5oz).  Coupled with that, I found it difficult to pick out individual flavours or varietals within the espresso (which may be due to my inexperience, but also may not).  Both of these are symptomatic of dull grinder burrs, and since my 2d hand flat burr grinder is 5 years old, it’s a safe bet that it would benefit from new burrs.  This would increase the amount of good espresso yielded during the brewing process.

So there you have it.  I’m not claiming to have invented anything here, not by any stretch of the imagination.  All of this comes from reading the work of other gifted people and putting it into some sort of process that I can follow in my own OCD manner!  Since I couldn’t find a step-by-step approach already documented anywhere online, I’ve written one in the hope that someone else might benefit from my messing about with espresso!  I’m not claiming that any of it is correct either.  Please feel free to disagree or challenge, or indeed add to and enhance this approach.  I’d love to hear your own experiences of using brew ratios.



  1. thanks for taking the time to do this, all those years ago :-). This is a very nice summary and approach. I'm getting a classic soon and will likely take a similar approach because of this.

  2. You have a real ability for writing unique content. I like how you think and the way you represent your views in this article. I agree with your way of thinking. Thank you for sharing. My First Espresso