As well as preparing the espresso machine, you need to make sure all other equipment items are ready for use. These include:

• • the grinder

  • tamp, dumpbox and milk equipment

  • service items.

Grinder

Grinders work by breaking up coffee beans between two plates or ‘burrs’. The result is coffee grinds of a uniform size, minimal heat generation and a full-flavoured coffee. Many grinding machines also have a doser that dispenses the correct amount of ground coffee into the portafilter to make a single or double espresso.

The grinder needs to be checked to make sure it is clean and in working order. Oily residue from coffee beans can build up on the inside walls of the hopper, the burrs and walls of the dosing chamber. Make sure these parts are clean to prevent rancid (stale) oils affecting the flavour and crema of your espressos.

To get a good idea of the effect that the size of the coffee grind has on the flow of water think of how water would flow through a funnel containing rocks and one containing sand.

To get the right grind, you may need to set the grinder from scratch. This may be required if:

• your grinder is new

• new burrs have been installed

• you have changed the type or supplier of roasted coffee beans

• the grind appears to be wrong perhaps due to someone inexperienced adjusting the equipment.

Once the initial settings are right, you may also need to adjust the grinder to take into account:

• humidity (the amount of moisture in the air)

• the condition of the burrs.

Coffee absorbs moisture. This means that the more humid the environment, the slower the water travels through the ground coffee. When the weather or your indoor area is very humid, you may need to adjust the grinder a little to produce a slighter coarser grind. When the humidity is very low, you may need to adjust it to produce a slightly finer grind.

Over time the burrs in the grinder wear and become blunt. Older burrs tend to have a larger gap between the two plates and produce a coarser grind. To make sure you get the right grind and extraction time, you may need to adjust the grinder towards the ‘finer’ grind setting.

Once the beans are ground, the coffee should be extracted within 15 minutes. If ground coffee is left much longer than this, it loses the valuable oils that give espresso its taste and smell.

Doser

Check that the doser fills the filter basket to the right level. The correct fill level is usually indicated by a line in the filter basket. If overfilled, water flow will be slower and your espresso is likely to be over-extracted. If the filter basket is underfilled, the espresso is likely to be under-extracted.