What are the characteristics of V60 and Kono drippers? Advanced pour-over coffee brewing techniques! How to brew a rich, layered pour-over coffee?

Understanding Gold Cup Extraction: Why Coffee with Same Extraction Rate Can Taste Different

As we all know, the concept of "Gold Cup Extraction" expresses that coffee has a "wide audience appeal" extraction range. When we control the extraction rate and concentration within this range, the coffee will be liked by the vast majority of people.

To put it simply, take extraction rate as an example. A coffee bean contains 30% soluble substances, and the Gold Cup Extraction considers delicious coffee to have an extraction rate between 18% and 22%. In other words, if we extract two-thirds of the 30% substances from the coffee beans, this coffee will be accepted by most people (considered delicious). Less extraction leads to under-extraction, while more extraction will cause the coffee to develop bitter, mixed, and astringent over-extraction flavors.

Applying this principle to coffee extraction means we need to control the extraction rate of this coffee powder to around 20%. But did you know that even two cups of coffee with the same extraction rate can produce extremely different performances under different brewing methods? One cup has more acidity and less bitterness, with rich layers; another cup has balanced flavor and mellow mouthfeel. So the question arises: why do such differences occur?

Actually, it's quite simple because the extraction rate of these two cups of coffee is calculated based on "average" values! It's very simple to extract 20% of soluble substances from a single coffee bean because there's only one object, making it highly controllable. However, if we have 15g of coffee beans, we're facing hundreds of coffee beans. Additionally, these coffee beans will be ground and crushed into countless tiny coffee particles, making calculation extremely difficult and unnecessary. Therefore, our measurement method is based on "average" values. And this is the key point that leads to differences in coffee performance.

Average value means that this coffee powder could either all receive uniform extraction, dissolving the same amount of substances, or it could mean that different coffee particles dissolve different amounts of substances due to varying extraction efficiency. Therefore, even two cups of coffee with the same extraction rate will produce different performances because the coffee particles receive different degrees of extraction. In other words, as long as we can understand this point, we can freely control the performance of a cup of coffee. For example: balanced flavor or rich layers.

FrontStreet Coffee often mentions that soluble substances in coffee have different dissolution rates due to varying molecular sizes. Although they all release simultaneously upon contact with water, the quantity released differs. First comes a large amount of acidity, followed by bitterness, and these flavors exist in mutual balance. Therefore, if we want to brew a cup of coffee with balanced flavor and mellow mouthfeel, we only need to ensure that the vast majority of coffee particles receive consistent extraction rates, or that the bitterness in the coffee can balance with the acidity; whereas if we want to brew a cup of coffee with rich layers, we need to maximize the differences in substances dissolved between coffee particles. Only then can the sweet, sour, and bitter flavors not tend toward balance, allowing the coffee to possess more layers (referring to taste layers rather than temperature changes).

Practical Methods for Coffee Extraction Control

Although it may seem complex, it's actually not difficult in practice. So FrontStreet Coffee will skip the complex theories and directly share how to implement this!

1. Retention or Removal of Fine Particles

Even with the highest quality grinders, ground coffee will always contain a certain amount of fine particles. Because coffee grinding is not absolutely uniform - there are both large particles and small ones, with differences as shown below. (The image below shows 15g of coffee ground at Ek4310 setting)

The smallest particles on the far right of the image are fine particles - coffee particles smaller than 0.3mm. Their presence can disrupt the uniformity of coffee extraction. Because of their small particle size, they dissolve all substances very quickly when in contact with hot water. In other words, they are more easily extracted. Therefore, when a batch of coffee powder contains an appropriate amount of fine particles, the coffee often tends to have richer layers. If we sift out the fine particles and use only similarly-sized coffee particles for extraction, the coffee's layers tend toward balance.

2. Contact Time Between Powder and Water

The premise of the above comparison is that during the brewing process, all powder and water contact time is the same. However, in actual pour-over brewing processes, not all coffee particles have the same contact time with water because pour-over coffee uses drip extraction rather than immersion (an extraction method like tea where powder is soaked in water). Therefore, this can also be a key factor in adjusting coffee performance.

It's well known that coffee brewed with V60 drippers has more layers, while coffee brewed with Kono drippers is more balanced. This is because the dripper structure affects water flow speed, thereby changing the contact time between powder and water. V60 drippers have faster flow rates and more gaps, causing coffee particles at different positions to receive varying degrees of extraction; whereas Kono, due to slower flow rates and fewer gaps, allows coffee particles more time to contact water for extraction, resulting in more balanced flavors. The performance difference between cone-shaped drippers and flat-bottom drippers follows the same principle.

3. Pouring Methods

In addition to these reasons, pouring methods also affect coffee performance. Things we often mention, such as using large water flow to raise the powder bed, or small water flow for slow circular pouring, all aim to change the final performance of a cup of coffee by altering the number and time of coffee particles in contact with water.

Since FrontStreet Coffee often mentions this, everyone can search for previous articles on their own, so we won't elaborate further here~

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