Posted on November 28 2018
Following our last blog post There's no need to Over Dose, where we discussed the amount of coffee (the dose) required for two coffees, this blog explores how getting the grind right is essential to extracting the perfect espresso shot.
The espresso machines use pressure to brew, this pressure forces the hot water through the coffee grounds. Too fine, and it won't get through, too coarse, and it will gush through and lose all its flavour.
Remember these two rules:
- If the coffee extracts too quickly, the grind is too course or there may not be enough coffee in the group handle
- If the coffee extracts to slowly or not at all, the grind is too fine or there's too much coffee in the group handle
Becoming aware of the way the grind looks, the volume of coffee in the basket, the speed by which the coffee is extracted and the way it looks, smells and tastes is essential to producing great espresso.
To produce a well rounded and balanced espresso shot, the extraction requires getting the following elements right:
The speed of the pour - did the espresso come gushing out of the group handle or did it drip out slowly? The extraction should flow through smoothly and consistently resulting in a thick golden brown crema.
The colour of the pour - did the colour gradually change from dark to light or did it lighten early in the pour? A very blonde (light) crema is over extracted and will taste bitter.
The aroma is a little harder to explain but essentially you should get hints of chocolate, maybe caramel and most importantly, coffee aroma.
The taste balance of sour (acidity), bitterness and sweetness. If it's too bitter check the grind isn't too fine, the harder it is for the water to push through the coffee the longer the extraction will take resulting in the shot burning the coffee. If it's sour, check the grind isn't too coarse. Sour and bitter tastes should be present in coffee, but it should be pleasant not nasty.
A good grinder is essential to get it fine enough. What should you look for in a grinder? Here's a very detailed guide from Perfect Daily Grind
We can always grind it for you but beans are best as they stay fresher for longer!
Now that the grind is right, you need to think about how much to put in the filter basket. This is important because if there's not enough coffee in the filter, the shower wont hit the coffee and water will pool on top of the puck creating a soggy mess in the group handle.
On a commercial grinder the dose will be set based on the grind setting. For espresso this is usually two clicks for a single about 12 g and three for a double about 20g.
Our technicians have many years experience and will set the grinder for our food service customers. They will generally asks customers not to change the grinder after they have set it, because in our experience, when the grinder has been messed with, it's usually followed by an urgent call saying "there's something wrong with the coffee!" But it's not the coffee, it's the grinder.
A few key points to remember:
Coffee will emit carbon dioxide (de gas) immediately after roasting and can take at least 7 days before it begins to settle and become more stable. The coffee can be used during this degassing process but it will taste much better if left for a few days so that the flavour profile can completely develop.
If the grind is correct, the flow of espresso will begin a few seconds after engaging the program button, this is called pre-infusion
Extraction should be around 25-30ml over approximately 25 to 30 seconds
The extraction flow should be rich and smooth resulting in a thick golden crema.
If the coffee extracts too quickly, the grind is too course or there may not be enough coffee in the group handle
If the coffee extracts to slowly or not at all, the grind is too fine or there's too much coffee in the group handle