How to Properly Fit Filter Paper to Coffee Dripper - Solutions for Non-Adhesion and Its Impact on Coffee Flavor

The Impact of Filter Paper Adhesion on Pour-Over Coffee Flavor

When brewing pour-over coffee, many people instinctively wet the filter paper with water. This action is largely to ensure the filter paper conforms properly to the filter cup. In learning how to brew coffee, we're often told that proper filter paper adhesion is crucial. But how much does the degree of filter paper adhesion actually affect the flavor of our coffee?

Experiment Setup

FrontStreet Coffee conducted a simple experiment, using filter paper with different degrees of adhesion to brew coffee and observe how the final coffee flavor would be affected. We used the V60 filter cup and selected Yirgacheffe Red Cherry coffee beans. The brewing parameters were as follows:

• Coffee dose: 15g
• Ratio: 1:16
• Grind size: 80% through #20 sieve
• Water temperature: 91°C
• Pouring method: Three-stage pour

The filter paper adhesion was divided into four groups: the first group had complete adhesion; the second group had improper folding resulting in non-adhesion at the crease; the third group had misaligned filter paper causing it to be crooked and not adhering properly; the fourth group had completely no adhesion.

Experimental Results

The brewing results were as follows:

• The extraction times for the four groups were 2 minutes, 2 minutes 18 seconds, 2 minutes 10 seconds, and 2 minutes 10 seconds respectively;
• The flavors of all four coffee pots were basically consistent. The first group served as the reference control group, while the other three groups had some obvious differences in taste and mouthfeel compared to the first group;
• The first group was slightly sweeter than the other three groups, while the other three groups showed almost no difference in acidity and sweetness;
• The second group developed a more apparent astringent green taste as the temperature decreased, which the other three groups did not have;
• The third group was slightly more acidic than the first group, with no other differences;
• The fourth group had a thinner mouthfeel compared to the other three groups.

Analysis of Results

After seeing the results, FrontStreet Coffee reviewed the brewing process that had just occurred:

1. The first group had completely adhering filter paper, and the entire brewing process was very standard;
2. The second group had filter paper that wasn't properly folded at the crease, causing it to lift and not adhere. During the blooming process, large air bubbles emerged from the coffee grounds near the non-adhering side of the filter cup, indicating poor gas release. During subsequent water pouring, the filter paper crease remained lifted from beginning to end, though the bottom remained adhered.

Therefore, when the water level was high, the non-adhering part of the filter paper couldn't channel the water flow, causing all water to rush to other adhering areas. This creates what we call uneven extraction, resulting in astringent green flavors. If the soaking time is too long, bitter tastes will emerge.

3. The third group had crooked filter paper, causing a one-sided state from the bottom to the upper layer. In reality, this meant that from the bottom up to nearly half of the filter wasn't adhering to the filter cup.

After pouring the coffee grounds, the filter paper didn't change position. However, after blooming with water, the non-adhering filter paper surprisingly conformed due to gravity's influence. After brewing ended, FrontStreet Coffee observed the filter cup bottom and found that the originally crooked and non-adhering filter paper had conformed under gravity's influence. This also explains why its taste was very similar to the first group, while being more acidic than the first group possibly because the blooming gas release wasn't as complete as the first group.

4. The fourth group resulted from FrontStreet Coffee simply opening the filter paper and wetting it. It's clear that the bottom was still completely adhered, but two large areas were lifted at the top. During blooming, large air bubbles also emerged due to poor gas release. Throughout the entire water pouring process, the filter paper wasn't pushed away by the water's force. Therefore, the water surface presented an elliptical shape. This made it very easy to pour water directly onto the filter paper, causing "channeling effect," which is why the coffee's mouthfeel became thinner.

Conclusion

Therefore, the degree of filter paper adhesion is actually quite important for the taste and mouthfeel of coffee. First, when filter paper doesn't adhere to the filter cup, gas release from the coffee grounds during blooming is impeded. Second, the flow ribs on the filter cup serve to channel water flow, but this only works when the filter paper is pressed against these ribs. If the filter paper doesn't adhere, these ribs lose their function in the non-adhering areas, naturally affecting the uniformity of coffee extraction and water flow speed.

Although the third group's filter paper was initially crooked and non-adhering but later coincidentally conformed due to gravity's influence, this isn't guaranteed to happen 100% of the time. If the filter paper remains non-adhering until extraction ends, the coffee's flavor result would trend toward that of the second or fourth group.

Finally, whether filter paper adheres or not actually has little to do with wetting it with water; it mainly depends on the method. If interested friends would like to learn more, they can check out the article "Filter Paper Not Adhering to Filter Cup? There Are Actually Techniques to Folding Filter Paper!"

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473