Yield, the second component to every espresso recipe, is simple to measure but a little more complex to understand and apply. Very simply, it’s the weight of the espresso in the cup. More yield means more espresso in the cup. Less yield means less espresso in the cup.
This week I’m going to explain yield, how it’s just a simple compromise, and how to get the most out of it. It gets a little complex so I strongly recommend reading my previous posts on Extraction, Strength and Dose before continuing.
Yield, at its very core, is a compromise. It’s a compromise between extraction and strength. You can have more of one, but it’s always at the expense of the other. If you’ve ever been frustrated by espresso, this is probably why.
Here’s how the compromise works.
More yield gets you more extraction, but lower strength.
Less yield gets you less extraction, but higher strength.
More yield means you’ve pushed more water through the coffee, extracting more flavour. But more water means more dilution, which makes the espresso weaker.
Less yield means you’ve pushed less water through the coffee, extracting less flavour. Because you’ve added less water to the equation, the espresso isn’t diluted as much and ends up stronger.
So there’s three main camps in the Battle of Yield:
- Those who seek strength and richness at the expense of extraction.
- Those who seek extraction at the expense of strength.
- Those who seek balance between the two.
If you’re looking for a stronger, richer espresso, you will be drawn to use recipes with lower yields. This will come hand in hand with a lower extraction. Cast your mind to the last ristretto you had—strong and rich, but sour and under-extracted.
If you’re looking for flavours achieved by higher extraction yields (more sweetness, ripeness etc.) you will likely be drawn to recipes with higher yields. This will give you the extraction you desire at the expense of a lower strength.
If you’re looking for balance, you will be drawn to recipes with yields somewhere between the two. But you’ll probably be disappointed a lot. A rich, sweet espresso can only be achieved with a high extraction and high strength. Unfortunately both cannot always be achieved simultaneously.
“What Matt? Have you given up trying to make great espresso? A good Barista can extract a coffee however they like!”
Sometimes your hands are tied, and you have to submit to compromise. Here’s why.
Watch this animation a couple times. It’s a regular 30 second espresso shot. You’ll notice no numbers apart from time. This is deliberate, because this example could be any combination of dose, yield, time, extraction or strength. The specifics don’t really matter. What matters is how the different elements move and change through time. I’ve used 30 seconds for this example as it’s what most baristas are familiar with. If your shots normally run for 22 seconds, all of this will happen within that timeframe; if they normally run for 40 seconds, the same applies.
Now, I want to give you a few specific things to look out for in this animation. After reading each one, go back to the animation and look for it. There’s a lot of things moving and changing through time in an espresso shot and you need to appreciate all of them at once to gain a thorough understanding. Please spend some time going back and forth to the animation – it’s really complex and I don’t want you to miss anything!
- Starts slow as the espresso drips out of the spouts. Then as time goes on it accelerates to the finish line. This increase in speed is because the coffee grinds’ flavours are being dissolved, and the remains are offering less and less resistance to the water pressure.
- Races to 50% with the first drops of espresso. Then it gradually decelerates through until the end. At the end of the shot it’s barely clawing its way forward. Coffee gives away a lot of its flavour very quickly, then it becomes harder and harder for the water to extract as much flavour.
- Stays nice and high at the start when the coffee has lots of flavour to give, but very quickly drops down as water is added. That high strength at the start is because the coffee has quickly provided the water with so much soluble flavour.
- The quickly diminishing strength at the end is because the coffee has almost had all of its flavour dissolved by the water. What’s left is hard earned. So, the water being pushed through the coffee is extracting a tiny bit of flavour, but mostly it’s just diluting the espresso.
- Someone who seeks out strength will stop the shot right before it starts rapidly diluting. In this example, that’s probably around 00:21-00:23.
- At the very end of the shot, yield is increasing very quickly, strength is decreasing very quickly, and extraction is increasing very slowly. You need more fresh water and longer contact time to get those last bits of flavour out of the grinds. Those difficult last bits of flavour are what people who chase a higher extraction are after. They’re OK with losing a bit of strength to get them.
So we have this compromise between strength and extraction. If you increase the yield, extraction increases and strength decreases. You cannot increase or decrease extraction and strength simultaneously by manipulating yield.
Let’s attach some numbers to this concept.
Now that you have fixed your dose, yield is really easy to understand and manipulate. I’ve found the best way to understand and communicate yield is as a multiple of the dose (some people prefer %’s, others prefer the ratio).
e.g.: a dose of 20g and a yield of 40g is a multiple of 2; a dose of 18g and a yield of 54g is a multiple of 3.
So we don’t need to worry about communicating dose any more – communicating just the multiple will tell us everything we need to know about that Barista’s prefered compromise.
The larger the multiple, the weaker and more extracted the espresso will be. These lighter, more delicate espressos will have multiples of 2.5 and above.
The smaller the multiple, the stronger and less extracted the espresso will be. These heavier, richer espressos will likely have multiples of 2 and below.
The range for today’s most common specialty coffees is between 1.8 and 2.5. There are most definitely exceptions to this rule but they are either very deliberate, or an honest mistake.
Here are some yield multiples plotted on a graph of extraction and strength. Note how increasing the multiple doesn’t result in a linear increase of extraction. As you add more water the espresso is being significantly diluted but the extraction is only increasing slowly.
No matter what espresso recipe you use, you will be stuck on that line. More yield moves you down the line, less yield moves you up the line. A very sobering, and sometimes depressing fact of coffee life.
Improving the Compromise
Alas! There’s hope yet!! You’re not completely stuck. There are ways to improve the compromise. This, friends, is the secret of why some Baristas just make better espresso.
Remember all those posts I’ve written, harping on about evenness of extraction? You were probably bored by me constantly mentioning it. Well it’s crucial here.
If you can make your extraction more even, your compromise is reduced. With more evenness comes a simultaneous increase in extraction and strength.
An uneven extraction will invariably under-extract some grinds. They’ll be left out, and won’t contribute any flavour to the brew. This means that your brewing is inefficient. With a particular dose and yield, an uneven extraction won’t dissolve all of the flavour that it could. With a more even extraction, more of the coffee will be extracted, which makes the espresso stronger. You don’t need to add more water or increase the brewing time because that flavour was sitting there all along. The even extraction just allows it to be dissolved in the water with the rest. Magic!
When you improve extraction evenness, you’re still stuck on the line. That hasn’t changed. What you’ve actually done is move the line! With the same yield, your espresso is now stronger and more extracted.
A more even extraction will move the line up and to the right. This means that, with the same yield, your espresso will be stronger and richer. BONUS!!!
Of course, the opposite holds true. If you extraction is less even, the resulting espresso will be weaker and less extracted.
Here’s a summary of everything you should be doing to improve extraction evenness:
- Use better baskets. I only recommend VST baskets and get nothing for it.
- Use a perfectly flat tamper that fits your basket real snug.
- Make sure you’re tamping perfectly level with your perfectly flat tamper.
- Distribute your grinds really well before tamping. It should look like a putting green before you even touch the tamper.
- Don’t knock the portafilter when inserting it into the group head. This creates channeling, which is death for evenness.
- Use a grinder that doesn’t produce too many boulders. Conical burrs are generally worse. Generally.
- Don’t use blends whose components have significantly different solubility.
With some of those boxes ticked, you’ll be able to make a truly, objectively, obviously, significantly better espresso. Tick all of them and you’ll see stratospheric improvement.
That said, the line does stop moving. Once you’ve maxed out all of those variables, it’s not moving any further and you’re back to being stuck on the line of compromise. A better line to be on, yes, but you’re still stuck on it.
So, Back to Yield
It’s a compromise. Improving evenness can reduce the compromise, but only so far. You have to choose a yield that creates the best balance of extraction and strength. Once you understand how that compromise works, it’ll be easier and faster to achieve an espresso you’re happy with.
You’ve decided on a dose and locked it in. Once you’ve settled on yield, lock it in too. Because next up we need to experiment with time!
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3 years later and I’m looking for answers to this question! Did you ever get any info about this, Callum?
These folks have gone a long way to showing how faster flow rates can increase extraction yields: https://www.sciencedirect.com/science/article/pii/S2590238519304102
What’s BH’s conclusion regarding this study?