30 Days of Blog - Day 25 - Espresso dose and distribution evenness

Welcome to day 25 of 30. I have once again had to take a day (or two) off from my writing here in order to get other things done in the real world. Hopefully the content will prove to be worth the wait.

Today I want to talk about coffee distribution and evenness in espresso (thanks to Cole McBride for the suggestion). This may be a loaded topic, but one I find of utmost importance for making the best tasting shots. 

When it comes to preparing espresso, there can be little argument that evenness in extraction is the ideal goal every time. It's sort of the pot of gold that everyone is shooting for. The understanding of what exactly that means and how exactly to achieve it seems to be the biggest problem for baristas lately. For this post I want to talk about two things in particular in regards to achieving this ideal even extraction. How to think about your grinds dose, and what can be done to achieve evenness.

When we approach espresso dosing and tamping the most important thing I teach is the consideration of density in the coffee puck. Think of the disc shaped coffee dose (it doesn't really turn into a puck until it's wet) that sits in a portafilter basket for a moment. The "evenness" we refer to has an enormous amount to do with a consistent density of coffee grinds throughout the entirety of the puck. If there is any variance from one portion to the next, you will have a path of lesser resistance for the water to flow through more quickly, leading to a combination of under and over extraction in the cup. So in my teaching this is the most important element in espresso preparation to focus on. More than tamping pressure, more than that extra .3g of dose, more than freezing your coffee (I dare you to pull that off in a busy cafe). 

One of the primary issues that leads to inconsistent dosing in the puck has to do with the nature of coffee grinders and how they deliver the coffee to the basket. My understanding of this stems from the old days of the Mazzer dosing hopper. Clickity-clack, clickity-clack. Those things were work horses for sure, but man did they suck at dosing straight down. Those old dosers had a tendency to fling the coffee out (toward the barista) and to the left. In order to mitigate this we always had to adopt the "portafilter dance", swinging the basket around in an attempt to catch all of the grinds evenly around the basket. Strangely, when done well this actually worked reasonably well. 

As grinder direct dosing and newer hopper designs have come about, the coffee is still getting dosed in a singular direction. It's just a different spot where it lands. The most notable grinders (that don't create a mound, but rather a fluffy pile that falls when shaken) are the Nuova Simonelli Mythos Clima Pro and the Mahlkoenig Peak. Both of these grinders still have other problems, but the nature of how the coffee grinds are delivered has been mostly addressed with these grinders. I won't count the EK43 here, because it has a lot to do with user error and quite honestly it is a mess when it comes to clean and concise dosing. *As a side note, the newest generation of espresso grinders should be getting introduced soon. Count me excited for those!

Anyway, the nature of the grinder dictates how coffee falls into the portafilter basket (for the most part). What I want you to think about here is any time the coffee is mounding in a single spot. It could be in the dead center of the portafilter, off center, on one side, etc. My analogy here comes from the baking world, so if you have ever done any baking and had to measure flour, you may understand this better. Any time a finely ground powder drops over and over in the same spot (let's say in a measuring cup), that spot becomes more and more compacted and densly packed. The nature of such finely ground power is that it can more easily compact together. Obviously ground coffee is not as fine as flour, but since espresso is quite fine it does have this compacting action when it is mounded consistently in the same spot of a portafilter basket. 

So here is one of our biggest problems. When we don't actively control where the dose is landing, like we did with those old Mazzer dosers, we end up with one highly dense portion of the puck and surrounding areas which are less dense. The degree to which this density varies depends on how much you let it mound up. So now you have to ask "what can be done?" Is there a way to mitigate the effects of self compacting coffee grinds in the portafilter. 

If you have been around coffee competitions in the past few years you might be thinking about a "distributor tool". I personally prefer to use my finger to distribute and level the coffee bed, mostly because that is the way I learned and it gives me a physical connection to the preparation of coffee. Use of your fingers may or may not be taboo to you depending on your local culture, health codes, and overall personal opinion. Dosing tools on the other hand are another discussion altogether.

I will write all about dosing tools tomorrow, so stay tuned for that!

For now let's talk about that initial dose.

My recommendation for this is a mindset. If you approach your dose with the attention on how the coffee is falling, you can adjust and ensure an even coffee bed from the very beginning. The rule of thumb here is that if you do it right from the beginning, you won't have to fix it later. Now not every dose, grinder, or setup will be perfect, so what can we do to adjust our dose density after dosing and before tamping? 

The first and most important thing is for you to pay attention to where the coffee is mounding, which will tell you where the high density spots are developing. The opposite parts are going to be your lower density areas. Your goal after understanding these areas of high and low density is to move coffee from the high density areas to the low density areas. 

Now before you think it is as easy as sliding the top of the high density mound over to the low density valley, remember that the bulk of your density is on the bottom of the basket! A good and thorough grooming of the grounds can potentially help, but it is vital to make sure not to use downward pressure on the already dense sections. The more effective methods I have seen use a sideways grooming of the dense potion, then pushing the excess downward into the gaps. 

Another technique that can help, especially when the mound is on one side of the basket is to tap the outside of the portafilter in an attempt to shift the density more toward the middle (remember that high density in the middle of the basket is still undesirable). The method here is to hold the portafilter in one hand and lightly tap the side of the portafilter that you want the density to shift toward. Essentially, the portafilter will move quickly while the coffee stays in the same place. The result is that the coffee mound moves toward the point of force. Technique wise, you should tap lightly and quickly, pulling your hand away from the portafilter immediately after the tap. This is a technique I learned in martial arts training. If you leave your hand in place on the surface it will reabsorb the kinetic energy that has been transferred, lowering the power of the impact. This technique is particularly useful when using the 20g VST baskets (buckets) like those used in competitions, as the coffee mound tends to be below the rim of the basket.

Of course this might also be an indicator that you are using too little coffee, or too big of a basket.

After your manipulations are finished, you should end up with a flat, or relatively flat surface to tamp. Tapping or grooming should always result in a flattening of the dose mound. Of course, the best course of action is to correct your inital dosing to mitigate the need for these techniques as much as possible. 

The result of all of this hard work is a much more even extraction. This has a major impact on the flavor of the espresso. I make coffee next to other baristas all the time, and am constantly asked why my coffee tastes better and flows better. This is my best answer. Even extraction helps you dial in properly, eliminate bitterness, and create highly sweet and delicious espresso. 

Of course this is only one step in making great espresso, but if you start here you will find that the rest follows suit more easily. You might have your own techniques which differ from mine to achieve even distribution, and if so I applaud you for discovering what works for you. These techniques work well for me, and that is why I teach them.

Thank you for reading today, as I said before tomorrow will be all about distributor tools!


Posted on October 2, 2017 and filed under Blog.