As a barista, I noticed many of fellow baristas remove the brewer from the carafe before all the water has dripped through. This was a common practice in most pours.

I wonder, does this “interception” technique make coffee taste better? If so, will it improve the flavor of brewed coffee universally and by how much? 

what is “interception”?

“Interception” is to cut water from fully dripping through carafe, as seen in the clip below.

When we pour water into coffee grinds, a number of compounds are dissolved by water.

Using “interception,” a portion of the dissolved compounds are removed with remaining water. 

Three stages of coffee extraction

This begs the question: Why do baristas love “interception”？ First, we need to know how coffee is extracted.

70% of a coffee bean is non-extractable lignocellulose, and 30% of the substance can be extracted. Of this 30 % of substances, good substances are usually only about 18% - 22%. Therefore, our goal is straight forward: we want to extract as much of the good from coffee as possible, and leave behind the bad.

Fortunately, not all substances in coffee are extracted by water at the same time, depending on the molecular sizes. The first extraction includes the smaller molecules such as “acidity,” then the medium molecules such as “sweetness," and finally the larger molecules such as “bitterness” or “astringency” that are unpleasant to taste. This provides a good understanding of “interception” technique.

The purpose of carefully controlling or deliberately cutting off the flow of water after brewing is to prevent the bad bitterness from affecting the cup of coffee.

“Interception” is one of the many modulation methods

Ultimately, the goal of interception is to avoid bitterness and astringency, and to make brewed coffee more delicious.

But there are many ways to modify extraction, so much so that "interception" has become the "lifeboat" for many baristas to avoid bitterness, perhaps because it is the most convenient (lazy) way.

Meanwhile, the disadvantages of “interception” technique are also obvious.

• Interception can easily lead to under extraction and a loss of coffee flavor during the middle and later stages.

• Beginning learners can struggle to grasp the interception point, which leads to an increase in inconsistencies of the brews.

• It takes about 30 seconds to a minute after the final pour until the drip is finished. During this period, baristas can become distracted by preparing the drink presentation. However, while using interception, we mustn’t leave sight of the brewer until it reaches “interception point,” which could unfortunately slow down bar flow during a cafe’s busiest hours.

I will be the first to admit, there are some prejudices about the "interception" approach. We will use the most intuitive experiments to unlock this method, but how much will interception help in the brewing process?

3 experiments- extraction recipe comparison

For this experiment, I selected three brewing cases. We tested a set of slightly different extractions methods for each example (standard without an interception, standard with an interception, adjustment variables without an interception) and compared the sensory of different extraction recipes.

Medium/dark roasted single origin 

Since third wave specialty coffee shops tend to serve lighter roasted espresso blends, it’s harder to find medium/dark roasted single origin coffee in specialty coffee shops.

Many baristas have grown accustomed to using light roasted beans. When brewing medium/dark roasts while using the same recipe, it is easy for a cup to become astringent. Is “interception” a way to redeem darker roasted coffees?

If you have an understanding of the roasting experience, you know most organic acids and enzymatic chemicals that cause floral and fruity aroma will decompose earlier on. However, caramel, spices, and other flavor substances are created when roasting temperature increases. Dark roasted coffee extracts most of its substances in the middle and later stages.

We compared four brewing recipes:

• Coffee: Yunnan Washed  

• Roasting level: Medium/Dark  

• Grind: 3.5 

• Water Temperature: 90℃

• Water/Coffee Ratio: 1:15

As we can see, “interception” in this case was not a good choice. By adjusting the temperature, the extraction was reduced. At the same time, the extraction of bitter macromolecule substances was mostly avoided, resulting in a good cup of washed Yunnan coffee.

High density coffee extraction recipe

Coffee from higher altitude is relatively more dense. In order to express the complexity of high-density coffee, roasters usually use a lighter roast. Because of its high density and light roasting profile, this kind of coffee is difficult to extract and has many fine grinds.

We compared three brewing recipes

• Coffee: Ethiopia Yirgarcheffe  

• Roasting level: light  

• Grind: 3.5 

• Water Temperature: 91℃

• Water/Coffee Ratio: 1:15
  
  
  
  

Larger dose extraction recipe

15-20g is the usual dose we use to brew coffee. Many baristas are not sure how to brew a larger dose, because the larger amount of grinds calls for a longer extraction time. This means that some of the coffee grounds steep for a long amount of time, which causes uneven extraction and higher probability for bitterness and astringency.

Would “interception” be a helpful way to avoid this problem?

We compared four brewing recipes

• Coffee: Yunnan natural   

• Roasting level: light   

• Grind: 3.5   

• Water Temperature: 90 Dose: 30g   

• Water/Coffee Ratio: 1:15

It's difficult to brew perfect coffee in a larger dose, but it is impossible to achieve this goal by changing one single parameter or simply cutting off the water flow.

After to reducing the water/coffee ratio and water temperature at the same time, a relatively balanced cup of coffee was finally achieved.

Through the sensory analysis of several different groups using common brewing methods, we can see that the interception technique used by many baristas can make for better cups of coffee, but it is not the best solution for every type of bean.

There are many ways to adjust extraction in order to brew more delicious coffee. No matter how we use it, we should adjust the variables according to the actual situation rather than copy all kinds of championship recipes. Otherwise, in the end, the cup of coffee will only perfect in figures but not in taste. 

What are your views on the various methods of brewing? We would love to exchange ideas.