There are three main things that you want to measure when making an espresso: dose, yield and brew time. Those three measurements you should, as a barista, check daily and some might even go so crazy that they check those for every espresso that they make.
It might be worth mentioning that from here on we will be talking only about double espressos. Let’s concentrate on the recipes.
This means the amount of dry coffee that you are using.
Usually dose is measured in grams and it is widely seen that for double espresso you should use something between 14 and 24 grams of coffee.
You should always start your espresso recipe making with dose. How many grams should you use? This is the easiest part in the recipe making process. Just check your portafilter’s basket size. The basket size should determine how many grams of coffee you should use.
Even though you have e.g. 20 gram baskets, you can use a bit more or less coffee depending on your roast. If your coffee’s roast is darker, then we suggest a lower dose (18-20 grams in 20g basket). For lighter roast we would use a bit bigger dose (20-21 grams in 20g basket).
If for some reason you are going to use less coffee, something like 14 grams, you would need to change your baskets to a smaller one. Using a smaller dose in a bigger basket you would likely create some channeling problems as there is too much space for water. Channeling means that the water isn’t running evenly through the coffee puck and it is creating channels to the puck.
This means the amount of liquid you have in a cup.
Traditionally yield is measured in milliliters (ml) or in grams. The advantage of measuring in grams is accuracy as your volume isn’t dependent on freshness of the roast as it is when measuring in ml.
Yield is often communicated in relation to the dose e.g. 1:2 which means that with 20g dose your yield would be 40g. More examples;
Using more water in relation to dose will dilute your espresso (make it weaker). Using less water in relation to dose will make your espresso stronger.
It´s suggested to start the recipe making from 1:2 ratio. With a 1:2 ratio the espressos are still pleasantly strong but not too strong to taste all the nuances. 1:1,5 ratio might make the espresso too overpowering and strong which hides all the good flavors that the coffee has to give. With some coffees it might be also wise to go to 1:2,5 so that the strength decreases a bit and makes the coffee open up more. When making a espresso recipe you shouldn’t change the ratio from 1:2 before you have tested at least few different brew times.
This means the time it takes to brew the espresso from the push of the button until you have reached desired yield in the cup.
Often it is considered that brew time for espresso should be between 20-35 seconds. Darker roasts shine with shorter brew times and lighter roasts with longer brew times. It’s because darker roasts are less dense and hence it’s easier to extract flavor from them. On the other hand, lighter roasts are “tighter packages” (denser) and you will need more time to extract the same amount of flavor from them. I suggest that with darker roasts it’s better to start brew times between 20-25sec and lighter roasts 25-30sec. Every coffee has a “sweet spot” in terms of brew time and it’s the barista’s job to find that spot with changing of the grind size.
More items to keep in mind to develop your recipe further
Temperature shouldn’t be first on your list but it is definitely something to consider if your espressos don’t seem to hit the sweet spot.
Pressure increases extraction so for lighter roasts it might be wise to use lower pressure in the start of the brew so that you will extract less acidity. Lower pressure in the start will also decrease channeling which will lead to higher extraction.
Even Extraction, Avoid Channeling
This means that the brew water runs through the coffee puck evenly and no segment of the puck gives more flavor than the others. Even extraction should always be the aim for a barista.