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How Grind Size Affects Espresso Extraction

Jan 1

Espresso grind size should not be too fine. It's been a mystery how to make espresso for a long time. Even the most skilled baristas occasionally make mistakes. It's worse if you use a superautomatic.

One thing remains constant is the grind size of espresso. To get that perfect shot, which retains sweetness but isn't too bitter, you must grind the beans to the perfect size.

Espresso Extraction

Water-soluble coffee beans contain around 28%. That means that out of the entire roasted coffee bean, you can extract about 28%. The remainder is cellulose and other plant material that make up the coffee bean's structure.

Water needs help to dissolve soluble chemicals. Coffee beans can be disintegrated if they are heated to boiling water. The structure of the coffee bean is extremely dense and complex. Water can't penetrate it easily. All the flavor is collected by the water on its way through.

Coffee tastes better when you increase the bean's surface area. This will result in gaps that let water through to the coffee, which allows for all its flavor. You can increase coffee beans' surface area by grinding the beans. The quicker the coffee reacts to water, the greater its surface area.

Water always extracts flavor compounds in this order regardless of the method: fats and acids, then sugars, and finally the plant fibers.

Acids, and fats, are the first compounds taken from coffee. Acids give coffee a bitter taste. It is easy to dissolve these compounds into coffee. This is the time when most of the light aromatics are extracted, including the floral and fruity flavor. Coffee's flavor is derived from the acidity and light flavors in its final cup.

We can't taste all the flavors in coffee so we need to control the extraction. We don't want all soluble matters to end up in our cup. A lot of those compounds are undesirable, and we want to avoid extracting those.

Chemistry is helpful because most bitter compounds can be hard to extract so we need to stop extracting too soon.

If we don't stop the coffee extraction at the right time, we can end up with a cup of coffee that is too extracted.


A cup that doesn't have enough soluble coffee solids will result in a cup that is too extracted. Many of the flavors that add balance to your shot are not extracted from the grounds. Acids are the compounds that can extract the most quickly, which means that a shot with too much acid can taste weirdly salty or without sweetness.

Extraction is directly related to strength. For a more strong coffee, use less water. While this may be possible, it's not the best. You can extract more coffee, but it's more difficult to extract all the flavor. The brew contains saturates. It is important to note that different saturation levels of compounds in coffee can be used to extract more. It is because we don't want to brew coffee at the right strength that it tastes bad.

Espresso extraction can be affected by the grind size. This is the most important variable when espresso brewing.

It is fascinating that a group composed of baristas as well as a roaster and scientists looked at coffee extraction. They found that grinding coffee too finely doesn't result in the best cup.

The Grind Size and Extraction

An espresso machine uses a pressure pump to push water through a "puck", of ground coffee. This creates a rich and concentrated cup of coffee.

Extra-fine grind settings at around 20 grams is a very popular method to make espresso. This is because it increases the coffee's surface area relative to water. This should lead to a greater extraction yield. Extraction yield measures the amount of soluble solids that dissolve and ends up in the final beverage.

How Grind Size Affects Surface Area

A University of Oregon study by Christopher Hendon was conducted with a barista and computational chemist. It showed that coffee shops tend to aim for extraction rates between 17 percent and 23 percent. A lower extraction yield is more bitter than a higher one.

The team brewed thousands and thousands of espresso shots before developing a mathematical model that could pinpoint the variables necessary to ensure consistent yield. They found that coffee can be too finely ground, which results in a shot being too concentrated.

Don't grind your coffee any finer than necessary. The coffee grounds that are too fine won't allow water to pass through. Water cannot pass through tightly packed coffee grounds because the puck is too small.

Coffee particle size is a major problem. The comparison of rocks and sand is a good example. You have the same weight. Water will flow through rocks if you put water on them. You can pour the same amount over the sand but it may take a little longer to get through the layer.

The other part of the problem is the tamping. The best way to compact coffee is to tamp finely ground coffee. This restricts the flow even further, if you tamp too hard.

Researchers discovered that a coarser coffee grind and a lower amount of ground coffee per cup is better. This creates more room in the coffee bed and results in a more satisfying brewing experience.

The Other Extreme

But, finer coffee can be just as troublesome as coarse coffee. These changes can be made by making very minor adjustments to the grind size.

Let's consider an extreme example. An espresso shot made with a medium-ground coffee will yield a 3 second pour. This would make it impossible to extract the acids. It will result in a coffee that is extremely under-extracted.

Espresso Variables, and Espresso Extraction

All things equal, roast degree will have as well an impact on the extraction. The same coffee bean will extract easier if it's roasted dark , compared to a lighter roast.

A double shot should contain between 14 and 21g of coffee. The best results are achieved when the quantity is within one gram.

Tamping will affect the flow rate of your coffee, which in turn impacts how much of the ground coffee is extracted.

Fines from a grinder are good as they clog your puck and increase flow. They reduce the contact time of water and coffee grounds by 20 seconds. The shot may not flow if there is too much finesse.

Don't be too rigid

Make sure not to take the creativity out of coffee brewing.

The human component of coffee is what makes it so special and why people love it. While the scientific component is essential in making decisions about flavor, it also allows us to make choices to improve our coffee. However, creativity and personal tastes are equally important.

This article was syndicated from Daily Preston UK News.