The Basics of Making Good Espresso
Making espresso is a craft. We may have visited shops where we prefer a particular barista to another and here’s why. Some people understand coffee better and use machines professionally. They understand the nuances of flavour and care about the quality of their cup. This is more likely to be found in specialty coffee shops than the common high-street profit centre.
Below are some basics to making great espresso and treating a coffee machine with respect. We will largely avoid milk texturing and grinder maintenance.
The espresso machine must have heated up with the water stable at around 90 to 94 Celsius. This means turning it on for half an hour and running the water through the portafilters (glossary at the bottom of the page) several times. Doing this once with coffee in the basket will help heat up the group-head.
All good espresso starts with a basic recipe. There is an in and an out weight to pay attention to. For example, we may have 20g of finely ground coffee and a post-brew weight of 40ml (g=ml). This is a ratio of 1:2. For a shorter, more intense and full espresso, a barista might use a ratio of 1:1.5; 1:2.5 for a longer drink with potentially more delicate flavours. Between these sweetness can be maximised but body or flavour is somewhat sacrificed. These are sometimes called ristretto for the former, and lungo for the latter – but be aware people perceive and name these differently.
To focus a little more closely on recipe, weigh the coffee dose into the basket and then attach the portafilter to the group-head. Place the cup on scales and stop the water flow a couple ml before the desired out weight.
When removing the portafilter from the group, flush water through the group for a second. This helps remove any lingering sludge from the shower screen and cleans it for the next brew.
Tap the coffee puck out and wipe all around the portafilter with a clean, dry cloth. Cleanliness helps avoid cross contamination from previous brews. Dose the coffee into the basket, tap the edges with the palm to distribute it evenly and tamp down. This creates a firm and level bed of coffee for water to be pushed through. If the puck is not level the coffee will channel. This is basically an uneven extraction with an unbalanced espresso.
It’s not necessary to push too hard and a level bed is what’s important. A nice way to measure this is to place a thumb and forefinger on the rim of the portafilter at opposite sides of the tamper. Twist the tamper slowly and see if the gradient changes on either the thumb or finger. If it doesn’t, the bed is level. I sometimes see people spinning the tamper on the coffee for spinning's sake. For making good espresso, this is as good as singing to a goldfish in the morning.
Wipe any remaining grounds off the portfilter before fitting it into the group. This helps avoid putting coffee into unwanted and hard to clean places. Don’t fix the portafilter too hard either. The rubber gasket in the group helps keep the temperature stable and water in the right place. Ramming it in too hard will damage the gasket and cause leaking.
Start the water quickly. If the puck is left in the group and the brew is not started, it will start to burn. Starting the water flow might mean pushing a button, swiping a paddle or pulling on a lever. Make sure to time the brew to record a repeatable recipe.
Timing is only a reference. Generally though, if water passes through too quickly (below 25 seconds), the coffee will taste sour and intense. This is called under-extraction. If it pours too slowly (over 35 seconds), it is likely the coffee will be bitter with a long, unpleasant aftertaste. There are certainly exceptions to this and a barista should be tasting their coffee every 20 minutes to ensure the recipe is as it should be. The burrs of a grinder will move and heavy usage causes machines to overheat. This will change the recipe. Keep your cups warm for greater heat stability.
Finding the right grind size
This can be tricky. Each time the grind size is changed, coffee will be wasted. Beans are stored in a chamber and the desired change may take place only after 50g has passed through. I prefer to first change my dose before changing grind size, but sometimes it's the only answer. Here's a quick summary troubleshoot, but only change one variable at a time.
Quickly poured, sour coffee
· Up the in coffee weight
· Adjust to a finer grind setting (keeping the same in and out weights)
Long pour, bitter and intense
· Reduce the in coffee weight
· Adjust to a coarser grind setting (small increments on the setting)
When close to a good recipe but the coffee still doesn't hit the spot, try changing the out weight and tasting the difference. This can be done more efficiently by using 2 espresso cups for one brew and removing the cups at different times. For example, 20g in feeds through to spouts. Remove one at 18ml and the other at 22ml. Taste the difference. If the latter is better, you know the recipe needs 44ml out.
When using the milk spout, always purge the steam before and after. This removes condensed water from the spout before use and cleans it of milk after. A stale, stinky, milky milk wand is the last thing we want.
Keep it clean
Always keep the espresso machine clean. In busy coffee shops, the machine is back-flushed and washed twice a day. Stale coffee oils are rancid and will negatively affect the flavour of all brews. This means using powdered soap and blanks to clean the internal pipes, clean cloth for the exterior, sponges and brushes for the hard to reach areas in the group and disinfectant. Don't forget to remove and wipe the basket clean. The grinder and its hopper should also be cleaned at least once a week.
If the water is too hard, it’ll damage the machine. Use a water softener or reverse osmosis to turn hard water soft.
The route to barista greatness
These basic tips will even help a donkey make better espresso. From here you can explore other sites with more in depth, barista material.
For a summary of the points, always remember (I’m not making a cheesy acronym):
Portafilter – The handle and basket which is fitted into the group-head
Group-head – The unit on the machine which holds the portafilter and where water is pushed through
Gasket – Rubber ring inside the group-head
Shower Screen - A screen in the group where water passes before hitting the basket of coffee
Basket – Held in the portafilter and holds the coffee
Blank – A basket with no holes used for back-flushing
Tamper – A carefully designed weight to fit into the basket and push coffee flat
Tamp – The verb to use a tamper
Milk Wand – For steaming milk
Back-flush – When blanks are fitted in place of baskets to cause water to go back through the machine’s piping
Channelling - When water passes through a coffee puck unevenly and may leave patches dry and untouched
Balance – When a coffee just tastes right
Intense – When there’s too much going on and it’s not fun
Ratio – Dry pre-brewed coffee to wet post-brewed coffee weight