Espresso grind size should be perfect, however, the finer grind is not necessarily more effective. Espresso making has been a challenge to master over the years. Even the best baristas occasionally make mistakes. If you're using a machine that's super-automatic, it's even more difficult.
There is one thing that's constant, the grind size for espresso is the same. In order to nail the perfect shot that keeps some sweetness and is not too bitter, you must find the ideal grind size.
Espresso Extraction
Roasted coffee beans are about 28 percent water-soluble. So, out of the whole coffee bean, you will extract around 28 percent. The remainder is mostly cellulose and plant material that form the structure of coffee beans.
Full story - Espresso Extraction and Grind Size
Water needs help to dissolve soluble chemicals. If you drop coffee beans in hot water, they only dissolve the outer layer. The coffee bean's structure is very dense and complex which means that water cannot move through it easily. The water is able to collect every flavor.
Coffee is more enjoyable when you expand the bean's surface. In this way, you can create spaces that let water penetrate the entire taste. Coffee beans can be ground to increase their surface area. Coffee beans are more reactive to water if they have greater surface area.
Water extracts flavor compounds according to the order, regardless of how it is produced acidic substances, fats sugars, fats, and acids, before converting to plant fibers.
We don't have the ability to taste all flavors of coffee, which is why we must be careful about the extraction. We don't want the entire substance that is soluble to go into the coffee. Some of these compounds are not ideal, so we attempt to stay clear of extracting them.
Fortunately, chemistry cooperates with us in this regard, as most bitter compounds are more difficult to extract. If we stop extracting in time, we only get the best substance.
Under Extraction
You will get a cup with a low amount of solids in the ground coffee. Many of the flavors that give balance to your shot aren't extracted from the grounds. Since acids are the compound that release the fastest, an under-extracted shot might taste bitter, strangely salty, and lacking sweetness.
The strength of a coffee is directly in relationship with extraction. For a potent cup of coffee, you can cut down on the amount of water you use. While it's possible, it isn't the best option. The greater the amount of coffee you extract, harder it is to extract out all the great flavor. The brew is saturated. It is crucial to remember that there are different levels of saturation of coffee's compounds can be utilized to get more. That's why when we brew the coffee in drips to strength of espresso it taste bad.
It's interesting to know that baristas, scientists and roasters examined the extraction of coffee and found that grinding too fine doesn't yield the best tasting cup.
The Grind Size and Extraction
Pressure pumps are used to force water into the "puck" of ground espresso. This results in a dense and concentrated coffee.
Extra-fine grind settings of around 20 grams are a common way to make espresso. This allows you to brew one shot. This is done to increase the area of the coffee's surface to water. This will result in a more efficient extraction yield. Extraction yield refers to the quantity of solids that are soluble and ends up in the final drink.
How Grind Size Affects Surface Area
An experiment conducted by Christopher Hendon, a computational chemist and a competitor barista, revealed that cafes strive for extraction yields between 17 and 23 percent. Higher yields of extraction can be bitter, while low yields can cause you to feel bitter.
The team prepared hundreds of espresso shots and came up with a mathematical formula to determine the variables that are required to ensure a consistent yield. They found that if coffee is ground too fine, the flow of coffee is sometimes too restricted and the shot gets over-extracted.
If you grind your coffee too fine, then you'll be aware of this. Water just doesn't pass through the coffee grinds when the coffee grounds are too thin. Water cannot pass through ground coffee that is tightly packed because the puck is too small.
Part of the problem is the size of the coffee particle. A good analogy would be the comparison between sand and rocks. The equivalent amount of sand rocks is equal in weight. It is possible to pour water over the rocks and it will instantly go through. If you put the same amount onto the sand it will take some time to move through the sand layer.
The other part of the issue is taping. If you tamp extremely finely ground coffee, you are able to pack it better, so the coffee puck is smaller. This will limit the flow more, if you tap too difficult.
The research team discovered that using a more coarse grind, and reducing the amount of ground coffee per cup is better. This will leave more room within the coffee bed creating a larger smoother, more even brewing.
The Other Extreme
But, finer coffee may be as problematic as coffee that is coarser. It is only necessary to make slight adjustments to the grind size, these changes are unnoticeable for the untrained eye.
Let's look at a more extreme case. If you use an espresso shot with a medium grind shots, which is the method that is used for drip coffees, your espresso will flow in three seconds. This would be way too fast, and it will only draw out the acids. Your coffee will be severely under-extracted.
Espresso Variables and Extract
The roasting temperature can affect extraction, however it's not a factor that determines. The same coffee bean is more efficient in extraction if it's roasted dark , as opposed to a lighter roast.
Double shots of coffee ought to weigh between 14 and 21 grams. For the best results, you should make sure to keep the measurement within one gram from the weight on the container.
Tamping can affect the rate of flow of your coffee, which then affects how much ground coffee is removed.
Grinder dust is beneficial since they can clog the puck and aid in flow. They create a 20-second contact time for water with coffee grounds. A lot of finesse could block the puck and cause the shot to stop flowing.
Don't be too strict
Coffee is a process that is creative.
The appeal of coffee and the reason why people are so passionate about it is that it is impossible to get rid of the human aspect. It's the scientific aspect which allows us to make choices about the flavor. We can make use of it to improve the quality of our coffee. But personal creativity and taste are equally important.