GETTING COFFEE SHOT CONSISTENCY
Even a difference of ±2g of coffee can massively affect extraction time and, as such, flavour.
So how do we guarantee consistency in any given espresso recipe, we’re measuring three things:
- DOSE – The dose of ground coffee in the portafilter basket
- TAMP – aim for about 13.5 kilograms of pressure
- YIELD – amount ‘ml/weight’ of espresso from the espresso machine
- TIME – it takes the machine to extract that yield from the dose
The dose, tamp and our yield are our controlled variables. The grinder adjustment and tamper affect the time a shot pours.
NOTE: Because coffee is organic and the process of making espresso is a manual one, the results – and the factors that determine them (humidity, temperature, air pressure, not to mention human error) – can impact on your getting the result you want.
The Step-by-Step Instructions
Each recipe starts with a fixed ‘brew ratio’. The most desirable tastes of espresso are usually achieved using a ratio around 1:1.5.
What does this mean? It means the weight (or mass to be accurate) of the brewed espresso is 1.5 times the weight of the dry ground coffee dose. For example, a 18g dose of coffee to yield a 27g espresso shot. So, a brew ratio of 1.5: 18g x 1.5 = 27g.
First, we dial in a ‘recipe’ first thing in the morning before the door opens. The Brew recipe will look something like this:
| IN (grams) | 18g |
| OUT (grams) | 27g |
| TIME: (sec) | 25 sec |
| BREW RATIO: | 1:1.5 |
Coming up with the above, involves experimenting. You’ll need to decide how many grams of ground coffee you’re going to put into your portafilter basket. Weigh and time your shots, synchronising the coarseness of your grind to find the ‘sweet spot’ where your espresso tastes its best, but once you have done this, you can recreate it every time and you’ll know that your coffee tastes the best it can.
STEP BY STEP PROCESS
- Place empty portafilter on a scale and tare your scales.
Start with scales, your portafilter, and 18g of espresso.
2. Place porterfilter on the scale & tare.
3. Dose your chosen grind profile into your portafilter
4. Re-weigh your grind in your portafilter. (discard or add some coffee as needed).
5. Tamper the grinds so that the bed of coffee is perfectly flat to ensure you achieve evenness of extraction.
5. Insert portafilter into grouphead.
6. Place espresso cup(s) on the scales and tare (zero) the scales and start extraction & start a timer as you press the pour button.
7. Watch the shot and the weighing scales readout – when it gets to the chosen weight, stop the shot. (this takes a little practice – dependent upon the speed of response of the scales, you may need to stop the shot at 28 to finally read a 30g shot).
THINGS TO OBSERVE:
Shot Too ‘Short’ – If your shot was too short, the espresso will be under extracted. This often results in salty or sour tasting espresso. Try tightening up your grind, this will slow the pour; this will give you a shorter shot.
Shot Too ‘Long’ – The longer the shot and the more water you’re pushing through your espresso, the more you’re extracting from your coffee and this will give you over-extracted espresso. This often tastes bitter, won’t have much flavour, and will have no lasting finish. If it’s over, then you might need to loosen the grind, making your grind coarser, which will speed up the pour.
Colour Changes – Observe the colour changes of the pour. An espresso, undergoes three general shade changes as the water pours through.
1st – ‘dark red-brown’ colour is the ristretto part, which contributes sweetness and body.
2nd – ‘caramel colour’ contributes balance and is the espresso part of the pour.
3rd – When the caramel ends, so does the shot, so when the pour changes to yellow or ‘blonde’, only bitter water is being extracted, and you need to stop! This blonding can happen anywhere between 15ml and 35ml, depending on the variety of coffee used, so every type of coffee will pour at very different lengths of time — 30mls in 30 seconds is just a guide.
Wettish Puck – The grind may be slightly too fine.
Cratered Puck – The temperature can be too high and you get a cratered puck, especially if the basket is not well loaded.
Summary
Proceed with caution, by only adjusting one parameter at a time.
When you have adjusted the grind, brew again – taking care to keep the ratios the same as the original. Taste and tweak accordingly.
That’s it. A simple way to benchmark your brew to help you make better espresso.
Whilst there are a lot of steps, the bottom line is that doing so, and hitting your recipe every time, keeps the quality of the coffee you’re sending out high and consistent. The trick is quick, calm execution – and the experienced high-volume barista will do this with seemingly miraculous, effortless cool.
So long as you have a smart system in place, weighing your shots is in fact quicker – and more consistent – than not weighing them (more on this later).
