Barista course · Episode 4

Understanding the machine

The full text of this episode — to read, look up and quote.

Cold open

This is your machine. And in the last three episodes we prepared everything. Bean, measure, grind.

Today you get to know your tool properly. Not every screw, but the things you really need to understand so that it works for you. And right at the start I will tell you one honest thing that many prefer to keep quiet.

We will come to that in a moment.

Where this sits in the five Ms

The fourth M, the machine. It has one task. The task is to force hot water through your coffee at a constant pressure and a constant temperature.

Constant is the key word. Let us look at how it does that.

Teaching: brew group and PID

Two things make the difference between coffee and espresso. The first is the group head, the heavy piece of metal through which hot water is forced into your coffee. On a good machine it is solid.

That mass stores heat and provides steady stability. It holds a stable temperature right at the brew head. Depending on the machine, a well regulated heating system keeps this warmth constant.

The technical term does not matter. The result does. The second is the temperature control, called a PID.

It sounds technical, but it is simple to explain. A PID holds the brew temperature constant to within a few degrees. Weaker machines can swing by ten degrees.

And ten degrees are the difference between sweet and bitter. The brew temperature stays steady between eighty-eight and ninety-six degrees. For the beginning, around ninety-three degrees is a good value.

This constancy is the reason you can reach café quality at home at all.

Chart: heating up, honestly

And now what I promised you. The honest truth about heating up. You often read a line like this.

Ready to go in two minutes. That is true and not true. After about two minutes the brew water is up to temperature, but the heavy portafilter and the group head are still cold.

If you pull your espresso now, the cold metal cools your water down and the espresso tastes flat. The honest answer is this. Give your machine enough time until everything really is warmed through.

That is when it tastes best. Exactly how long depends on your machine. A large machine with two boilers needs considerably longer.

A bean-to-cup machine is usually ready sooner. A few minutes more patience is almost always a good rule of thumb. In a hurry?

Then there is the professional's trick. Flushing. You simply run hot water through once, briefly.

The water runs through the empty group head and the locked-in portafilter. That pre-warms the metal in seconds. Not quite as good as full patience, but much better than starting cold.

Remember: warm does not mean ready. We tell you things like this because we want your espresso to succeed, not because the advertising sounds nice.

Teaching: water and the steam wand

Two more things that count in everyday use. The water. Your espresso is more than ninety per cent water.

So do not use hard, heavily chlorinated tap water, but filtered or soft water. You can taste it, and your machine scales up more slowly. On most machines the water tank comes out and you can see the level.

The steam wand. That is the movable metal arm on the right of the machine, the one we will use later to foam the milk. One important habit from today on.

After every foaming, wipe the wand immediately with a damp cloth and blow it through briefly. Dried-on milk is almost impossible to remove afterwards. More about the wand in episode seven.

Hands-on

Now you, and today entirely without coffee. Switch your machine on. Lock the empty portafilter into the group head.

It should heat up with everything else. And then, if you like, flush once. Trigger a short water release and let the hot water run through group head and portafilter.

Then feel the portafilter carefully, and notice how much warmer it is now. That is your warm-up routine from now on. Every morning, before the first espresso.

Common mistakes

Take a calm look at your machine. Where is the switch? Where is the pressure gauge?

Where is the wand? Where is the tank? Make yourself familiar with every part.

Three stumbling blocks. One. Starting cold because the light is green.

The portafilter takes longer than the light. Two. Using hard tap water and then wondering about scale and flat taste.

Three. Not wiping the steam wand after foaming. The most common care mistake there is.

Recap and your task

Let us hold on to this. The solid group head and the PID control provide the constant temperature that makes good espresso possible in the first place. Warm does not mean ready.

Give it time, or flush. Use good water and wipe the wand. Your assignment.

Heat your machine up properly, flush once, and make yourself familiar with every part. In the next episode things get serious. That is where you come in.

With the perfect puck. omaneo and YOU can do espresso.