Espresso Extraction

Brewing espresso, or pulling a shot as it is more commonly called, is straightforward enough. You need fine coffee, hot water, and 9 bars of pressure. There are even guide lines around how much coffee and how much brew time is needed.

However, more often then not, yields are perfect, times are exact, but shots are still terrible. At this point we need to understand the theory and where the rules come from, so that we can break them.

Introduction: The goal.

Welcome to the wonderfully maddening world of espresso. If you are new, you are quickly going to find out that espresso is far more rewarding as well as far more unforgiving than your run of the mill drip coffee. Where drip coffee might have certain attributes more enhanced or more diminished based on variances in your brew process, you will still end up with a drinkable cup of coffee for the most part. That said, espresso will quickly become very bitter, sour, or even watery based on different attributes, and that assumes you don't end up choking your machine and making a mess. Our goal here is to understand the different variables and rules that go into pulling a perfect shot of espresso, and how to break the rules when they lead you to a sink shot.

Chapter 1: Ratios, time, and grind

First things first, lets go over the absolute basics just to get those out of the way. Espresso, largely speaking, comes down to ratios. We used to measure in volume, but quickly discovered that just like baking, mass is the way to go. In the event you don’t have a scale, it would be worth your time to pick one up. I have a few listed out in the equipment section if you need help on where to start. Though there are $100 scales, a $20 scale will work just fine. When pulling a shot you are going to start with your dose weight, this is going to be the amount of ground coffee that you have in your basket. Generally speaking this is going to be an amount in the range of 7-8 grams for a single shot, or 17-18 grams for a double shot. For the sake of this document, we are going to stick with double shots as those are the most common.

Let’s assume that we start with our 18 grams of ground coffee in the basket. We are going to want to select a brew ratio that we want to stick with. Espresso generally ranges from 1:2 to 1:2.5. In other words, for every 1 gram of ground coffee you would want 2 to 2.5 grams of espresso. If we are working with 18 grams of ground coffee, we want 36 to 45 grams of espresso in our cup. Most folks I have spoken to seem to lean to the 1:2 range, so far the time being we will stick to that. Just to call it out, there are other types of shots you can pull as well, those being a ristretto or restricted shot and a lungo or a long short. A ristretto generally uses a ratio of 1:1 to 1:1.5 where a lungo uses a ratio of 1:2.5 to 1:3.

Now that we have the ratio aspect out of the way, the next main variable that we are going to want to target is going to be time. The general rule of thumb is that you want to pull your shot in a time frame of 20 to 30 seconds, with a general agreement being anywhere from 23-27 seconds. Something to keep in mind is that this time window is used for both your standard single and double shots. So you don’t have to worry about doubling or halving time for standard shots. As a quick note, you might have seen something called a turbo shot referenced on the internet elsewhere, this is a type of shot, and it is pulled far faster, but it's nothing we are going to cover just yet.

So, at this point, we know how much ground coffee we are going to be using, how much espresso we expect out, and about how long it should take, these are all largely going to be dependent variables for now. What do we do when we either pull a shot too fast, or we pull a shot too slow, what is the independent variable we get to control? The first variable we are going to play with is grind size. If you have spent any amount of time on espresso forms or reddit, you have probably seen the words “grind finer”. This is solid advice to a point, but it has also become something of a meme and a running joke for any espresso related error.

So if the answer isn’t always to grind finer, what is the right answer, and when is it the right answer? In the event your shot pulled too quickly the general notion is to grind finer. If your shot is pulling too slow, or you end up choking your machine, the general notion is to grind more coarse. Eventually you are going to get to a point where you are pulling a correct ratio in the generally agreed upon time frame. At this point, you are going to realize one of two things. Either your shot is delicious and you are happy with it. Or, you did everything right and the shot was still terrible.

Chapter 2: sour to bitter and back again

Coming Soon: