As an educated guess, the authors of this article must have at least pulled one shot of espresso from the machine because they love espresso and didn’t like it or didn’t understand why the shot tasted odd. Well, that is channelling and getting rid of it is impossible. What a nuisance since the shot eventually got out of balance due to poor extraction.
Now, about espresso channelling: what do we call it, and how is it best avoided so that we will produce a shot that tastes better than the previous shot? Issues on what causes channelling will be put into words, and issues on correcting them will be considered.
What Does Channeling Mean?
That is termed channelling when the water passes through a very tight section of the coffee puck, which is not meant to pass if one wants to have such fixation. Water does not fully percolate the puck and enable the flow out through weak points, thus leaving some areas wet and at other points dry. That is what keeps an espresso shot from attaining one of its core requirements of being harmonious. Rather, you get an espresso shot that feels both numbered and sour at the same time, thanks to just a little bit of over-extraction and some under-extraction in different parts of the shot itself.
Identify Channeling
An irregular shot is the most obvious indication of channelling, particularly with a naked portafilter.
A strong spout of water or divided streams of coffee certainly can be taken as an indication of channelling. The sources, however, which are more subtle in kind, seem to be noticed, such as espresso served with sour and bitter tastes or maybe sake covering the nasal with a very thin body and watery texture. This is the appearance of a channelled shot.
Causes of Channeling
Imperfect filter circles preparation, such as problems in grinds with all the tamping and the coffee distribution, usually leads to channelling. The following are the critical causes to avoid:
- Fine particles present in the ground coffee: When your grind is too fine, water will not saturate all the properly packed coffee grounds, leading to increased pressure. Due to the density of the coffee grounds, water goes rampaging around the puck rather than through it. One needs a really fine espresso grind for their machine flavour. But there’s this really fine line that has to be crossed.
- Bad Coffee Dispersion: Loose packing of coffee grounds in the portafilter means that water will find its way to the most porous area. This creates channels in the coffee bed, which is undesirable. So, achieving proper distribution is also important so that the whole puck gets saturated with water instead of forming areas where water cannot penetrate.
- Bad Tamping: Tamping is essential so that there will be consistency in every shot of espresso. If the puck is tamped harder on one side than the other, some areas will be less dense to let water flow without much resistance. That difference leads to channelling and spoils extraction, making the shot not worth it.
How Channeling Acts to Affect Espresso’s Extraction
Roasting damages the flavour of the coffee. The smoother the flow, the less some areas of the puck will go unnoticed while the others will pick up unpalatable and bitter over-extraction. Intermediately well-extracted espresso is very challenging in terms of flavour because it is very well-balanced but confusing, with a combination of flavours that seems to have been designed for different types of beans.
The Espresso Channeling Control Process
The good news is that you may take measures to avoid problems like channelling and getting a better espresso. Here’s how:
- Grind Constantly: One of the best tools for minimising channelling in espresso lattes is a quality burr grinder. When roasted coffee is ground into powder, all the fine particles must be approximately the same size. If they are mostly of a uniform size, then water will tend to flow evenly through the whole bed rather than through random sections, thereby reducing the chance of channelling. Let it not be too fine so that it can be extracted. There must be enough surface area in the grind. Other means are developed to avoid channelling: attempt to make the grind less fine instead of drinking your coffee from the bottom up through the cup.
- Pour Coffee Evenly: While tapping the coffee grounds, ensure that they are distributed evenly on the portafilter basket before tamping. Some baristas use the Weiss Distribution Technique. This device carries soft wires evoking clumps of coffee ground and redistributes them uniformly. This easy step proves crucial in ensuring all weak points are removed, thus allowing effective, even extraction.
- Change Both Same Tension: Proper tamping uniformly and consistently must be done for shot execution. At this stage, the instruction is to keep the handle parallel to the base and push along the puck uniformly. A calibrated tamper, if used consistently, will help you apply equal pressure to every puck, thus improving uniformity without having to make any extra effort.
- Allow a few seconds after tamping for everything to settle down, and make sure the puck and everything else are squished flat.
- Regulate your flow and pressure: Some baristas will want to hit at a higher pressure, not necessarily a better shot. That is a tragedy because very high pressure at the pre-infusion stages could ruin the coffee puck, leading to channelling. All efforts must be made to ensure that the water flows pretty steadily so that the breaking down of the structure of the coffee puck is not felt at any point in the extraction process.
Pro-tip: On Shot Security
Bottomless portafilters are great for looking at shot flow and using the measuring gauge for the espresso machine. Once you see that the shot starts to come out, look to see if holes or erratically sized streams of coffee have emerged. Normally, when areas are wetting where no shot is coming out, the shot comes out spurting, followed by the barrel channels. Add on corresponding measures like redistribution, adjusting grind or tamping to get flow with no spurts, smooth and constant.
Final Thoughts
It takes a lot of work to extract espresso. However, paying attention to the size and distribution of the grind, as well as how much and where you tamp it, can minimise that effect. Shooting for uniformity of extraction and preparation in these ways will get you perfect savoury shots that taste great. With time, you’ll learn how to hone what you’ve been given so that each shot you pull will reach its maximum potential with every bean you use.
