Making an excellent tasting espresso often involves more trial and error than other types of brewing.
Espresso is brewed faster, and with a far smaller quantity of water, than filter coffee.
This means that we have little room for error when it comes to getting sufficient extraction with our espresso shots. It’s easy to brew a sour espresso if our ground coffee does not extract into our brewing water properly during our (roughly) thirty second brewing time.
Here we are going to go through five techniques that can help you avoid this “under extraction trap” and pull better espresso shots at home.
Warm Up Your Espresso Machine Before You Brew
Espresso should be brewed at 194-205 Fahrenheit.
If your espresso is brewed at a lower temperature than this, then less extraction will occur.
Extraction is the process where flavorful compounds in your ground coffee dissolve into your brewing water. Lower temperatures reduce the rate that solids dissolve in liquids.
While your espresso machine will heat your water to this ideal temperature, if your water hits your coffee bed in a cold portafilter this temperature will likely drop below 194 Fahrenheit.
You therefore want to warm up your portafilter before making your espresso.
The easiest way to do this is to pull a “dummy shot”, that is a shot without any coffee in your portafilter.
Just pulling one of these before your actual shot should significantly raise your brewing temperature, resulting in better extraction and a tastier final drink.
Purge Your Grinder Before Loading Your Dose
If you grind your own beans then you should throw away the first couple of seconds worth of coffee that comes out of your grinder before you load up your dose.
This is particularly important when you brew your first shot of the day.
After you grind your beans there will always be a small amount of ground coffee left in your grinder’s burrs.
This leftover ground coffee will be the first bit of coffee that gets ejected the next time you grind.
Your brewing water will run faster through these stale grounds compared to fresh grounds.
This means that combining ground coffee of different freshness can increase the chances of your coffee extracting unevenly. This uneven extraction is one of the most common causes of sour tasting espresso.
Brewing with uniformly fresh coffee will drastically lower the chances of uneven extraction occurring.
Use the Correct Type of Portafilter Basket for Your Coffee Grind
A portafilter basket is the removable dish where your ground coffee sits in your portafilter.
A portafilter and its removable basket
You may have noticed that your espresso machine comes with several portafilter baskets (usually between two and four depending on the machine).
There are two types of portafilter basket: single wall and dual wall.
Single wall portafilter baskets have dozens, if not hundreds, of tiny holes in their bottom that your coffee can run though. Dual wall portafilter baskets just have one such hole.
The red circle shows the single hole in the dual wall portafilter basket
If you are making your espresso with pre ground coffee, then you should use a dual wall portafilter basket.
As I said earlier, the longer that coffee has been ground for, the faster that your brewing water will run through it.
Pre ground coffee therefore needs an extra bottleneck to ensure that there is enough contact time between ground coffee and water for proper extraction to occur.
The dual wall portafilter’s single hole provides this bottleneck.
If you are brewing with coffee you ground yourself then use the single wall portafilter basket.
The dual wall portafilter basket has some downsides, most notably creating artificial crema because of the pressure that a single exit hole generates.
Therefore if your bed of coffee alone can create enough resistance against your water flow to allow for sufficient extraction, you should stick with a single wall portafilter basket.
To reiterate:
- If you are brewing with pre ground coffee, then use a dual wall portafilter basket.
- If you are brewing with freshly ground coffee then use a single wall portafilter basket.
Don’t Overfill Your Portafilter Basket
Every portafilter basket is designed to hold a certain quantity of ground coffee.
Overfilling your portafilter basket reduces your brewing water’s ability to flow evenly across your coffee bed.
Uneven contact between ground coffee and brewing water leads to uneven extraction which (again) generally results in a sour tasting coffee.
Your portafilter basket’s maximum dose will either be printed on the outside of the basket itself or in your espresso machine’s instruction manual.
Underfilling your portafilter basket generally is not an issue, but overfilling it should be avoided.
Distribute Your Coffee Grounds Before Tamping
When we tamp our coffee grounds our main aim is to create a level bed of coffee.
This, again, is to promote even extraction.
If our bed of coffee is not level then our brewing water will flow more quickly through the less densely packed parts of the coffee bed than the more densely packed parts
These less densely packed parts of the coffee bed will become over extracted, with the more densely packed parts potentially becoming under extracted.
Many beginner espresso makers think that we tamp our coffee grounds to create this level bed.
This is not the case.
Tamping simply compresses the coffee bed. The levelling out should happen before you tamp.
Even if you keep your tamper level when tamping, if your initial bed of coffee is not level then your final tamped bed will also not be level.
Although there are some fancy (read: expensive) tools to help you even out your coffee bed, one of the most effective ways is to simply tap the portafilter sideways against your hand until you can see that the bed is level.
Follow this up with tapping the bottom of the portafilter against your counter to flatten it down and you’ve distributed your coffee grounds as well as any tool can.
You can find a video of someone doing this below:
Even after you distribute your ground coffee you still need to make sure your tamp is level.
The best way to do this is to tamp with your portafilter sitting on a flat surface, rather than holding it up in the air. If your portafilter does not have a flat bottom (if it has spouts for instance), then you can hang the edge of its bottom off a flat surface while you tamp.
Use Coffee Beans Roasted For Espresso Where Possible
Coffee roasters understand the specific challenges that come with espresso brewing and will therefore select and roast beans in a way that will help you overcome these difficulties.
Coffee beans specifically selected and roasted for espresso tend to have the following characteristics:
- They are roasted darker, as darker roasts extract more quickly than lighter roasts.
- They have an oily sheen on their surface as this helps generate the crema that characterises espresso.
Crucially coffee roasters who produce blends designed for espresso often have brewing recipes specific to that blend. These recipes cover:
- The ideal dose and yield (brew ratio)
- The ideal brewing time
These recipes have usually been developed through taste tests carried out by the roasters themselves and can therefore drastically reduce the amount of trial and error you need to pull excellent shots.
Final Thoughts
Small tweaks to your brewing can make a big difference in how your final espresso tastes.
Hopefully these tips can help you level up your espresso making skills.
This article was contributed by Oli Baise. Oli is a barista who runs the coffee blog: Drinky Coffee
