Repeat this process, slowly adjusting the grind setting each time, until you are able to achieve 34gr of espresso, from 17gr of grinds, in between 20-30sec. If you are using the barista express, do not fixate on the “Espresso Range” marked on the pressure gauge. It is widely agreed upon that the best shots are actually pulled from 12 o’clock and onward on the dial.
(Tip: if you cannot achieve this flow rate because you are at the min or max grind setting, you will need to adjust the internal burr setting to give yourself more range)
Now that you have achieved a reasonable flow rate, it’s time to learn the fundamental concepts of espresso extraction that will help you turn your drinkable shot, into a GREAT shot. Espresso extraction has 3 key pillars, that form the foundation of how a shot tastes. Dose, yield, and time.
The one thing to understand about dose, is that it only determines how MUCH espresso you can make at a certain brew ratio.
For example, if you want to be brewing at a typical 1:2 brew ratio, a dose of 16gr will yield 32gr of espresso. A 20gr dose? That’s right! 40gr of espresso.
Your dose size is really only limited by the filter basket. The larger the basket, the larger the shot you can probably manage to pull. You also don’t want to go too low with dose, as this will create too much distance between the group head and you coffee puck leading to pooling. All Breville’s other than the dual boiler and oracle machines use a slightly smaller 54mm size portafilter, meaning that if you want to play around with dose, I’d caution against going much higher than 18gr, and slightly lower doses can actually be beneficial. What’s important in terms of dialing in, is to pick an appropriate dose for your machine, and keep this number fixed throughout the rest of the process.
Now that we’ve locked in our dose. We will move on the second pillar of dialing in which is yield. Yield, in combination with the dose, creates what is often referred to as a brew ratio. How much coffee (the dose) to how much espresso (the yield). Changing this ratio, plays with the balance of “extraction” and “strength” of the shot.
As you pull a shot, you are continuously adding more water, therefore diluting or reducing the “strength”. But you are also simultaneously increasing how much coffee goodness you’ve pulled from the beans or “extraction”. Obviously, there are limits to this. If you let a shot run for a minute, by the end you would still be reducing the strength by pouring more water into the cup, but no-longer be getting any more extraction. The beans have nothing more to give. This chart helps to explain this. As you can see, as the extraction percentage gets higher (we move from left to right), the strength decreases at an ever accelerating rate.
So that means there is a sweet spot. That sweet spot will depend on personal taste, again there’s no ONE answer. A shorter ratio like 1:1 will be very strong, but may taste sour or underextracted to some. A long ratio like 1:3 or will be weaker, but some find it is sweeter and more balanced. You have to experiment. I recommend starting at a 1:2 as a standard midpoint, and adjusting from there to individual taste preferences. A good way to understand how the flavours change as a shot progresses is to do an exercise known as the “Salami Shot”. What you do is switch to a different glass every 5 seconds as your shot runs. Let the shot run extra long, maybe 40 seconds. This way you can taste what flavours are added to the shot at each stage of the extraction, and start to fine tune your palatte to whether you like the flavours of a longer or shorter shot.
Finally we come to grind size, which impacts the shot TIME. This is the final pillar of dialing in espresso. Brew ratio had a large impact on overall shot flavour. If brew ratio is a macro adjustment to flavour, time will be your final micro adjustment. The average espresso pull runs around 20-30 seconds. This is a BIG range. Again I recommend starting in the middle at 25 seconds to reach your desired yield, and then start adjusting the grind size up or down from there to taste.
When it comes to comes to grind size, it helps to visualize how the water is running through the puck. A very coarse grind is like a box of pebbles. Water will pass very quickly over the rocks, and come out the other side looking pretty much the same. In coffee terms, the contact time will be too low, and the resulting taste will be sour and unpleasant. At the other end of the spectrum, for a fine grind we can visualize a box of fine sand, the water will seep through very slowly, and if the sand is too fine, it will start to pool on top. A shot that is too fine will often taste burnt and bitter because the contact time was too high which scorched the coffee or simply over extracted it