How to make a perfect espresso?

It is possible to make a perfect coffee-quality espresso at home with some trial and error. Here is a barista's advice for those who own an espresso machine.

Coffee beans

Buy your coffee beans from a specialist supplier who knows the age of the beans and where and when they were processed and roasted. Fresher beans make a better espresso, which should be viscous and full-flavoured with a good crema. Bad coffee will be thin and flat. Always buy whole grains. Fresh beans should be stored in a dark, cool place at a constant temperature. It is not necessary to store the beans in the freezer. A cupboard away from a heat source will suffice, but use them within three weeks. Make sure the beans are stored in an airtight container.

Roasting

Your bag of coffee beans should have a roast date on the back. The beans should be used between four days and three weeks after roasting for optimum flavour. You don't have to be a professional to make a good espresso.

Grinding

It is essential to grind well as this controls the extraction rate, which in turn affects the flavour. If the beans are ground too finely, a burnt or 'ashy' flavour can result. If ground too coarsely, the espresso will taste watery and thin, as the water will pass through too quickly without extracting all the flavours and oils from the coffee. Paul describes the perfect texture for an espresso grind as 'like flour with a little salt or sand'. The ground coffee should clump together a little when you squeeze it (but not too sticky). For filter coffee, the ground particles should be more like breadcrumbs. It is therefore important touse a coffee grinder electric or manual with grind adjustment.

Clean and dry

Make sure there is no moisture (or old coffee beans) in your filter and porter basket. If the coffee comes into contact with moisture, it may start to extract too soon. Use a cloth to wipe the parts.

Stuffing

Serious baristas should invest in a tamper to compact their coffee evenly in the basket. Fill the basket about three quarters full with ground coffee. Tap the basket on your bench to 'collapse' the coffee and ensure the basket fills evenly. Add more coffee and let it settle until it is full, but not too full.

Pack the coffee: Paul grips the tamper like a doorknob and leans on it from above with a straight arm "about 15 kg is ideal". If you turn the basket over after tamping, the coffee should stay in place.

After tamping, the basket should be about four fifths full. If the coffee is too hard against the shower wall of the machine, you may get an uneven extraction; too far and the espresso may taste like coffee grounds. Paul uses the analogy of a watering can: water poured from too high a height will hit the ground (the coffee) with too much force and turn it over, producing coffee grounds.

The purge.

Purge

your machine by running water through it before making your espresso.

Make the espresso.

Different baristas use different rules to ensure consistent and well-balanced espressos. Some, like Marco De Sousa Rosa, the 2017 French champion, advocate weighing both the dry coffee and the final wet espresso. According to De Sousa Rosa, a good "brew ratio" is about two parts dry coffee to three parts wet espresso. So 20g of dry coffee grounds should make a final espresso of 30-40g, depending on your taste.

Paul's rule is to go by volume: "30 ml in 30 seconds". Espresso cups generally range in size from 60 to 90 ml, but Paul's ideal dose is 30 ml. If your machine takes longer than 30 seconds to produce a 30ml shot, your grind is probably too fine and could taste burnt.

(Note that Paul recommends playing with your grind before anything else, you can also try changing the extraction rate by varying the amount of dry coffee you use. Less coffee will result in faster extraction and vice versa).

Signs of good coffee

Initially, the machine will deliver drops before a steady stream of espresso. The fresh coffee will be slightly viscous and almost seem to rise due to the oils in the beans.

Your 30ml espresso should have a nice creaminess on top. This is the lighter, fluffier substance on the surface. The crema looks like tiny bubbles and is reddish-brown or nutty in colour and dissipates after a minute or two. The absence of cream is a sign that your coffee beans have passed the test.

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