Espresso Grinding 101: How to Grind Coffee for Espresso

When I first invested in a high-end espresso machine and grinder, I expected to brew some of the best espresso I’d ever tasted. After all, I had spent a considerable amount of money on the equipment, so it had to be good, right? Not so much.

However, my initial attempts at brewing espresso were just… okay. That’s when I realized that a great espresso shot isn’t just about the machine or the beans; it’s about nailing the grind size.

In this article, I’ll take you on a journey through the world of espresso grinding and explain why it’s crucial to your coffee-making success.

The Key to Better Espresso: Your Grind Size

I firmly believe that grind size is the single most critical factor when it comes to making top-notch espresso at home. Why, you ask? Well, let me share a secret with you: extraction is WAY more important for espresso than it is for any other brewing technique, and your grind size is the best way to change extraction. Let me explain.

The success of your espresso brewing hinges on a myriad of factors, including the water temperature, the water-to-coffee ratio, and the time the water is in contact with the coffee grounds. However, with espresso, time is of the essence. You only have around 30 seconds to brew the perfect shot, and if anything goes awry during this short window, you’ll end up with a less-than-desirable outcome.

Espresso coffee grounds are incredibly fine, primarily because of the minimal brewing time involved. More surface area equals faster extraction. But here’s the catch: if your grounds are too fine, the water won’t flow through them quickly enough, leading to over-extraction. Over-extraction can result in undesirable flavors in your cup, such as bitterness and astringency, as it pulls out compounds like oils and the cell walls of the beans, which can break down if heated too long, leaving overwhelming bitterness.

On the flip side, if your espresso grounds are too coarse, the water will pass through them too rapidly, limiting interaction and leading to under-extraction. Under-extraction results in a different set of unsavory flavors, like sourness, acidity, and vegetal notes because you never get to the part of the extraction where natural sugars and bitter compounds, which balance these flavors, come out into your espresso.

To put it into perspective, espresso machines use approximately 9 bars of pressure, equivalent to about three times the pressure in a car tire. At this intense pressure, even minuscule adjustments to your grind size can dramatically affect how long water interacts with your coffee grounds and the speed at which it flows through them.

Why Espresso Grounds Shouldn’t Be Too Fine

Finer grind sizes mean your puck compacts more, making it challenging for water to travel through the coffee puck, thus increasing brew time. Grinding too fine can also speed up the extraction to the point where it gets out of control and imparts a nasty bitterness to your cup. Moreover, finer grinds boast more surface area, allowing for greater extraction within a given timeframe. However, there’s another factor at play with super fine grounds.

When you tamp your finely ground coffee, it condenses further in the portafilter. If the grounds are too fine, it becomes even harder for the water to traverse through the compacted puck under the tremendous 9 bars of pressure your espresso machine exerts. This can lead to the dreaded puck crack. When the puck cracks, water flows through the path of least resistance (through the fissure), bypassing the rest of the coffee grounds.

In this scenario, grinding finer can paradoxically result in under-extracted espresso, which manifests as sour, acidic, or vegetal flavors in your cup.

Why Espresso Grounds Shouldn’t Be Too Coarse

On the other end of the spectrum, coarser grounds permit water to flow through them more quickly, especially under 9 bars of pressure, because they compact far less when you tamp them. Since the water spends less time in contact with the coffee, you’ll end up with under-extraction, and your shot time will fall short of the coveted 30 seconds.

Again, under-extraction will lead to a sour or overly acidic espresso shot that lacks flavor and complexity.

Espresso Grind Size and Dose

Grind size is not the only factor to consider; the finer your grind, the more grind retention you’ll encounter. Grind retention is when grounds cling to the inside components of your grinder and never make it into your portafilter. It’s inevitable, even on high-end grinders.

The problem with grind size and your dose when it comes to espresso is that smaller coffee particles (like those you want for espresso) are more likely to cling to the inside of your grinder.

Suppose you weigh out 20 grams of beans, the standard dose for espresso, and then grind them. In that case, you might lose 1 to 2 grams to retention, which can significantly affect the coffee in your cup.

Weighing your beans before grinding and your grounds after grinding helps you understand the extent to which retention affects your coffee. This knowledge empowers you to adjust your process accordingly, either by grinding more beans or compensating in another way.

In any case, I recommend weighing your coffee after grinding to get the exact dose, even if that means a little is wasted each morning.

How to Grind Coffee for Espresso

Now, let’s get into the actual process of how to grind coffee for espresso.

Step 1: Find Your Baseline Grind Size

A standard shot of espresso uses 20 grams of coffee grounds, takes 25 to 30 seconds (typically closer to 30 seconds) to extract, and yields 40 grams of brewed espresso. Your goal is to grind 20 grams of coffee, pull your shot, and obtain precisely 40 grams of brewed espresso within the 30-second timeframe.

Now…get ready for that NOT to happen right away.

To get there, start with a grind size you believe is right. You can look up recommendations for your specific grinder, or just start with a consistency that looks close to powdered sugar.

Begin your shot, using two timers - one for the entire shot duration and another for the dwell time. The dwell time is the duration from starting the shot until you see the first drip of espresso in your cup. This delay is caused by water pumps, which most espresso machines use. Since your grounds aren’t fully exposed to water during this time, a good rule of thumb is to halve the dwell time.

So, with two timers, start the first one as you start pulling your shot, then stop the first and start the second as soon as you see espresso start to come out. If you have 4 seconds on the first timer, halve it to get 2 seconds toward your shot time. If you have 28 seconds on your second timer when the scale shows 40 grams (or whatever your ideal yield is), then you have a total of 30 seconds, which is perfect.

You’ve now found your baseline grind size, and you’re one step closer to espresso bliss.

Step 2: Make Adjustments Based on Taste

After your initial shot, you can make changes to any portion of the brewing process. However, I strongly advise against altering your grind setting, unless you need to make major adjustments. If your espresso is disgustingly sour, make your grind size a little finer. If it’s overly bitter or tastes burnt, make your grind size a little coarser.

Even small adjustments to grind size can cause significant variations in your espresso. Grind settings are excellent for making big adjustments; start with these. But once your espresso is decent, move on to make finer adjustments.

Step 3: Adjust Other Parameters to Dial In Your Perfect Espresso

Fine-tuning your espresso is where the magic happens. Small adjustments are best made using other parameters like dose, shot time, and water temperature, which have less of an impact on your final product.

• Dose: Increasing or decreasing the amount of coffee in your portafilter can influence the concentration of flavors in your espresso. A higher dose will result in a more intense brew, while a lower dose will yield a milder taste.
• Shot Time: Altering the shot time can be a game-changer. A longer shot time extracts more flavors from the coffee but can eventually lead to overextraction and burnt flavors, while a shorter time produces a milder cup but could result in underextraction, depending on your other parameters. Adjust in small increments until you get something you’re happy with.
• Water Temperature: Temperature plays a crucial role in extraction as well, with hotter water always leading to faster extraction. Cooler water extracts fewer compounds overall, especially when you’re only brewing for 30 seconds. This leads to a milder taste, while hotter water results in a richer, more intense flavor. If your espresso machine has a PID for temperature control, make small adjustments based on taste.

A Note on Puck Preparation

How you prepare your coffee puck can significantly affect your espresso shot, too, so it’s worth mentioning how to dial in this process after you get your ideal grind size for espresso set up.

Tamping, in particular, plays a vital role in controlling how quickly and easily water flows through the puck, influencing extraction time. Less pressure during tamping can lead to shorter shot times and less extraction. More pressure will make it harder for water to move through the voids between the coffee particles, leading to more extraction…to a point.

If the puck is too compact, it’s prone to cracking under the 9 bars of pressure. This can create cracks in your puck, through which water can rush and barely come in contact with your grounds. Channels can also form in the puck if it’s not uniform, leading to uneven extraction, sourness, and off-flavors.

To mitigate these issues, ensure consistent tamping pressure and technique, maintain a flat, level puck, and use a puck rake to remove clumps and reduce the risk of channeling.

Wrapping Up: Grinding Coffee for Better Espresso

In the world of espresso, achieving the perfect shot is an art form that combines science, precision, and a dash of personal taste. While a high-quality espresso machine is undoubtedly important, the grind size is the linchpin that holds the entire process together.

By mastering the art of espresso grinding, you’ll be well on your way to brewing consistently exceptional shots, ones that rival those of your favorite cafes. So, next time you fire up your espresso machine, remember that the secret to an outstanding cup lies in the grind. Happy brewing!

Frequently Asked Questions

Why is grind size so important for making espresso?

Grind size is pivotal for espresso because it directly affects the rate of extraction. Espresso’s unique brewing method offers a mere 30 seconds to extract flavors, making precision paramount. Too fine a grind can result in over-extraction, producing bitterness, while too coarse a grind leads to under-extraction, causing sourness. It’s all about finding that sweet spot, where water flows perfectly through the coffee grounds, extracting the right compounds to create a balanced, flavorful shot.

Can a finer grind ever lead to under-extraction in espresso?

Yes, a finer grind can surprisingly result in under-extraction when brewing espresso. When grounds are too fine, they compact more densely in the portafilter, impeding water flow. Under the immense pressure of an espresso machine, this can cause the puck to crack. Water then rushes through the path of least resistance, resulting in an under-extracted shot, which may taste sour, acidic, or vegetal. So, remember that grinding finer isn’t always the solution to fixing sour espresso; it’s all about finding the right balance.

How do I adjust grind size without affecting the overall quality of my espresso?

The key is to make larger adjustments using grind size while keeping other parameters constant. If your espresso tastes bitter, coarsen the grind slightly. Conversely, if it’s too sour or acidic, grind a bit finer. However, for fine-tuning, it’s best to leave the grind setting alone. Instead, adjust dose, shot time, and water temperature. Small changes in these parameters can subtly alter the flavor profile without drastically affecting the quality of your espresso.

What role does tamping and puck preparation play in espresso quality?

Tamping and puck preparation are crucial in ensuring even water distribution and flow through the coffee grounds. A consistent tamping pressure is vital for a balanced extraction. If the puck is too compact, water may struggle to flow, leading to over-extraction in some areas. On the other hand, an inconsistent puck can create channels that water can rush through, causing uneven extraction and off-flavors. To maintain quality, use a puck rake to eliminate clumps, ensure an even puck, and maintain a level surface for the water to interact with the coffee grounds consistently.