Make "delicious coffee" based on chemistry and physics

byNathan Dumlao

The coffee that the barista brewed in a cafe, a coffee shop, etc. is more tasty than the coffee brewed at home and it feels "delicious". So what's the difference between coffee brewed at home and coffee served at shops? So that is Associate Professor of Computational Materials Science and ChemistryChristopher H HendonHe explains how to put delicious coffee from the viewpoint of chemistry and physics.

Brewing a great cup of coffee depends on chemistry and physics
https://theconversation.com/brewing-a-great-cup-of-coffee-depends-on-chemistry-and-physics-84473

For filter coffee, included in coffeeOrganic acid·Brown substance·ester·Heterocyclic compoundComponents such as 1.2 - 1.5% of the total, this proportion increases to 8 - 10% when using an espresso machine. Although this coffee ingredient is related to feeling that people are "delicious", it is technically very difficult to make coffee with a component ratio of 8 to 10% or more.

Hand drip,Turkish Coffee,Aero Press,siphon,French pressIn the extraction method such as coffee ingredients, the proportion falls within the range of 1.2 to 1.5%. So why are the ingredients almost the same, will the taste change depending on the extraction method?

First of all, it is an element called "temperature". Except for the method of making a concentrate like espresso, the way of putting in coffee is roughly divided into two types: "to soak coffee beans in hot water" and "to let hot water pass through coffee beans." And from the perspective of physics, the biggest difference is that the temperature of the coffee fine particles becomes higher when "immersing in hot water".

byChristy

The temperature of the coffee particles is related to the "speed" at which coffee flavor moves from hard particles to water, the higher the temperature the faster the speed. At this time, if the temperature of the particles is high, "delicious" elements trapped in the coffee particles will be extracted well, but if the temperature is too high, elements not wanting to dissolve out in hot water like spicy It will melt away.

In the method of immersing beans in hot water, "time" can be controlled relatively easily, but the method of passing hot water through coffee beans is more complicated. The pace at which hot water flows differs depending on the way beans are ground, as a result of which the extraction time changes. Also, not only to finely grind the beans but also to increase the amount of beans will slow the time until the hot water falls into the cup, so the extraction time will be longer. If you reduce the amount of beans you can increase the proportion of hot water to coffee beans, but on the other hand it is necessary to shorten the extraction time, etc, rather than the method of "immersing in hot water" There is a need to think of several elements, which is far more complicated work.

And even if coffee is brewed using the same extraction method / tool as your favorite barista, the taste will be different. The quality of coffee depends on the size of water and coffee bean particles.

bySabri Tuzcu

First, calcium ions andBicarbonateThere is soft water with less soft water and hard water with more of them. Coffee made with soft water is sometimes expressed as "sour" but acid becomes stronger, but coffee made with hard water is slightly dusty because bicarbonate is neutralized by acid contained in coffee is.

For delicious coffee it is not too acidic and not too powdery, just a good middle flavor is required, but many people do not know the concentration of bicarbonate in water they are using. In order to ascertain how much the taste differs depending on the water, it is recommended to extract coffee with Ebian, which has the highest bicarbonate concentration among the water sold in plastic bottles.

Also, the size of coffee bean particles is a factor that greatly changes the taste. In general, it is said that when using a rotating blade type grinder, the size of the particles are disjointed, while the grinding mill type can be ground evenly and finely. However, there is an argument as to how much grind it is, at a certain school we tell students to grind finely and finely so that the surface area of ​​beans is maximized, and at another school we suppress the harshness In order to teach it to grind coarsely as much as possible. In other words, it is best to grind beans according to the taste of drinkers.

byAnthony Tran

And the important thing is the freshness of the coffee beans themselves. Roasted coffee beans contain a considerable amount of carbon dioxide and volatile constituents, but over time the ingredients will escape from the beans. Coffee after the volatile ingredients have gone out will be less flavored, so it seems that cafes sticking to coffee do not use beans for more than 4 weeks from the date of roasting. Also, since deterioration of coffee is relieved by preserving in a cold place, if you want to keep coffee beans fresh at all, it is recommended to put in the freezer with it in a closed container.

As you can see from the above contents, various elements including science are involved in one cup of coffee, which is why one cup of a shop is finished to feel "delicious" than one cup drinking at home It is. However, because delicious coffee is not based on mathematical one perfect algorithm, it is made to fit the human tongue, so it is important to repeat the experiment and pursue the coffee for your tongue It can be said.