There is seemingly an endless number of variables you must consider when preparing a high-quality espresso. For example: the dose, yield, extraction time, and grind size, as well as tamping and distribution techniques.
If you’ve ever wondered why your espresso shots still don’t taste quite right, even considering all these variables, it could be due to a common issue known as clumping.
Coffee clumps can form for several reasons and ultimately can cause channeling that affects the extraction. Essentially, it is imperative to reduce clumping as much as possible to achieve the best results from your coffee.
What Causes Clumping?
In simple terms, clumping usually occurs when coffee is ground for espresso.
When grinding coffee for espresso, it needs to be ground as finely as possible; however, when coffee is ground very finely, clumps can sometimes form. A grinder with a weight-based grinding system that includes a double clump breaker can help with this.
Clumping can be due to an excessive amount of oils in the coffee, issues with the flow of ground coffee from the grinding chamber to the chute, or an electrostatic charge produced when grinding the coffee.
Beans containing more oils, such as darker roasts or old and rancid coffee, can clog the grinder. These oils then stick to the burr surfaces, which can cause clumping.
Environmental conditions, like high humidity and temperature levels, can also cause ground coffee to stick in the grinder chute. This, in turn, blocks the flow of ground coffee from the grinding chamber to the chute and can result in clumping.
The last factor is static electricity. Coffee beans can sometimes “pick up” electric charges as they pass through the burrs. Since ground coffee contains very little moisture, it can cause some particles to stick to surfaces or clump together.
Why Do Clumps Cause Problems?
While clumping may seem insignificant, it has significant repercussions on espresso extraction.
Water always seeks the path of least resistance through the puck. Because clumps are densely packed, water cannot easily pass through them.
Instead, water is forced to pass through other parts of the puck that are less clumped. This is known as channeling and it creates a host of problems.
Channeling affects the flavor and mouthfeel of your espresso; it can result in a more watery and less flavorful espresso.
Essentially, channeling means that some parts of the puck are not extracted enough, while others are over-extracted. Naturally, this results in a sour and bitter-tasting espresso, meaning you won’t be able to fully enjoy your coffee.
Additionally, clumping is often not consistent, so it can be difficult to predict when or with how much it will occur.
Clumps can come in various sizes, amounts, and densities. Consequently, it’s a challenge for many baristas.
How Can It Be Prevented?
There are measures you can take to reduce clumping. First and foremost, you should check your grind size. Although espresso requires a fine grind size, it’s also possible to grind too fine. This increases the likelihood of clumping. By making the grind size a bit coarser, you may be able to reduce clumps.
Similarly, it’s crucial to keep your grinder clean and in good condition. By periodically removing old and rancid ground coffee residues and any oil buildup in the grinding chamber, you minimize clumping.
Though both practices have their limits. Ultimately, to consistently achieve good results, investing in a high-quality grinder is necessary.
Benefits of Reducing Clumping
In fact, a more uniform particle size distribution and less static buildup reduce the likelihood of clumping. As a result, you can achieve a more uniform extraction and thus experience the full spectrum of coffee flavors.
High-quality grinders can reduce the workload for baristas. This is because they don’t have to spend time manually dispersing and breaking down clumps in the portafilter.