Espresso is a thick, concentrated, and syrupy shot of coffee. It’s ideally brewed at 9 bars of pressure to allow complete extraction quickly.
The correct grind size of the coffee beans is the key to brewing the perfect espresso. Otherwise, the coffee will be sour, thin, and watery.
The optimum grind size for espresso is a fine grind of 1/32 of an inch. The grounds should be fine but not so fine that the machine cannot push the water through the beans. A good rule of thumb is that the beans should be ground to the consistency of table salt.
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Finding The Correct Espresso Grind Size
To find the correct espresso grind size for a particular machine, brew a cup of coffee as a test. The grind is too coarse if the water comes out too fast and the brew is thin and watery. Set the grinder to a finer grind setting.
If the water takes too long to run through your espresso machine, the coffee grounds are too fine, and a coarser grind needs to be used. Coffee bean grind sizes vary from machine to machine, so experiment with a few cups to find the right grind size.
The Best Beans For Espresso
Fresh beans are just as crucial for quality espresso as the correct grind size. Do not grind too many beans—just grind enough for the espresso. Grinding small batches of beans ensures the beans stay fresher longer. Storing coffee beans in an airtight bag in the freezer keeps the quality for up to a month.
The best beans for brewing espresso are medium-dark to dark roasts. These beans extract faster than lighter beans. Medium-dark and dark beans are also rich in oils which produce a thicker crema.
Dark roast beans have a shinier hue than lighter roast beans. They are heated at the highest temperature of 100 degrees Fahrenheit., which produces the oils that make espresso so distinctive.
Additionally, dark roasted beans brew faster than lighter roasts because the beans are denser. These beans are roasted at higher temperatures, so they are brittle and fracture easily, allowing a quicker extraction. Dark roast beans are also better for a fine grind which is another reason they are the best for espresso.
Espresso Grind Vs. Other Grinds
There are three factors to consider when choosing a grind size: contact time, extraction rate, and flow rate. The extraction rate of coffee grounds increases with a larger area. So, to increase the surface area, use finer grounds.
Finer grounds produce stronger coffee because they release more caffeine into the brew. A fine grind over-extracts flavor while a coarse grind under-extracts. Over-extraction is due to the amount of water that covers the surface area.
There are generally five different coffee grind sizes: Coarse, medium-coarse, medium, medium-fine, and fine. However, another grind size exists—extra coarse. Other brewing methods and different flavor profiles choose which grind to use.
| Grind Size | Looks like | Best for |
|---|---|---|
| Extra Coarse | Peppercorns | Cold Brew Coffee |
| Coarse | Sea salt | Percolators, French Presses |
| Medium Coarse | Rough sand | Chemex, Clever Dripper |
| Medium | Regular sand | Siphon Coffee Maker, Drip Machine |
| Medium Fine | Table salt | Aeropress, Conical Pour-Over |
| Fine | Table salt | Moka Pot, Espresso |
Again, the finer grounds cover a larger area, resulting in a stronger flavor and more caffeine.
Pre-ground coffee limits brewing to just one type. If you use freshly roasted beans, you can grind the beans to the correct grind size. Whole beans give more options into what coffee can be brewed and what machine is used.
Blade Grinder Vs. Burr Grinder
There are two versions of grinders used for grinding coffee beans, blade grinders and burr grinders. The main difference between a blade grinder and a burr grinder is that blade grinders chop the beans, while burr grinders crush them.
Each has pros and cons, depending on personal preference and brewing styles. As every budding barista knows, brewing coffee correctly is a process of trial and error.
Burr grinders crush the beans to a specific size. There are two horizontal rings, one facing upward and the other blade facing downward. The beans go in between the two rings and, after breaking apart to the appropriate size, get pushed down into the container.
Blade grinders are similar to food processors. Unfortunately, the blades chop the beans into uneven pieces. This results in unevenly ground coffee with coarse and fine grounds. This unevenness results in over-extracting some grounds while others remain untouched.
Burr grinders are expensive and noisy but are also very consistent in their grind size. Blade grinders are cheaper and quieter, but sometimes the friction of the burrs heats up to the point where they burn the coffee beans. For the home barista, the choice between the two is a personal preference.
For the best espresso, a burr grinder is the best option.
Benefits of Freshly Ground Coffee
Fresh coffee beans stay fresh longer than pre-ground coffee beans. Roasted whole beans contain carbon dioxide, which prevents the beans from oxidation and staling. The beans can last up to two weeks at room temperature.
Once coffee beans are ground, the surface area is exposed to oxygen and starts to lose flavor. This is why coffee grounds become stale in just a few days. If pre-ground coffee is needed, it is best to buy it in small amounts.
Coffee starts losing its flavor as soon as it’s roasted. Ten hours after the beans are roasted, the subtle, fruity notes are no longer detected. Freshly roasted beans should be ground close to steeping time to allow the full taste of coffee to shine.
How To Make Espresso
Dark roasts are best when making espresso, as dark roasts have a deep flavor profile and rich oils. The key to perfect espresso is freshly ground roasted beans. You can use pre-ground beans, but it won’t be the same.
Coffee grind size is the main element during the extraction process. Extraction is the process of dissolving flavors from coffee grounds in water. A perfect-tasting cup includes the correct coffee-to-water ratio, temperature, brew time, and the right grind size.
The ideal water temperature for espresso is between 195 degrees Fahrenheit and 205 degrees Fahrenheit. Most espresso machines heat the water automatically. However, if the espresso tastes bitter, you must adjust the temperature.
1) Prep The Machine
The espresso machine should be turned on in advance to allow it to warm up. Most machines have an indicator light to tell you when it is ready. Next, check the group head to ensure it is not too hot, or you will wind up with burnt espresso.
Flush the machine with water to ensure the water is siphoning correctly and warm up the group head. Place the coffee into the grinder and select the correct setting. Espresso uses a fine grind, but this can vary from machine to machine.
If milk is steamed, the temperature of the group head needs to be readjusted for brewing, or else the next batch of beans will burn.
2) Pre-Infusion
Pre-infusion is the continuous introduction of water at low pressure until static pump pressure is added to the brewing cycle. This low pressure allows a constant water flow to saturate the coffee puck. Once this happens, complete extraction is achieved.
Fix the portafilter to the group head and make sure it snaps into place. This stops the channeling of water and avoids over-extraction. Doing this allows a small amount of low-pressure water to soak into the puck before the primary infusion.
3) Brew Time
Espresso brews in 25-30 seconds. Wait until the coffee in the group head loses its dark color, then pull a 1-2 oz shot. The crema at the top should cover the entire shot and join back together if you break it.
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