What's the use of espresso and filter paper? Why does espresso have filter paper?

A friend found that recently many coffee shops knock out the powder cake will have white paper. So after he arrived at Qianjie Store, he couldn't wait to ask about Qianjie's real paper. If you look like this, you can guess its true identity!

That's right! It's filter paper, a round piece of filter paper. As we all know, the main function of filter paper is to filter out coffee grounds, even if it is placed in a powder bowl. However, in addition to filtering, it can also have other uses when added to Italian coffee making, and the specific effect will change depending on where it is placed.

In fact, Qianjie has mentioned its role in most articles before, but it has not been detailed. So today Qianjie plans to come and chat about the advantages and disadvantages of using filter paper in the making of Italian coffee.

1. Adding filter paper to the bottom of the powder bowl Generally speaking, when it comes to adding filter paper to the powder bowl, the high probability means adding it to the bottom of the powder bowl. Because adding a piece of filter paper to the bottom can not only reduce the bitterness of the coffee, but also increase the cleanliness of the coffee,

We all know that in the extraction of espresso, there will be a lot of fine powder that will be pressed out of the powder bowl along with the coffee, because these coffee powders are extremely small and are not within the blocking range of the filter holes of the powder bowl. So when the coffee machine starts high-pressure extraction, these small coffee powders will flow out of the powder bowl with the coffee and fall into the cup. The fine powder itself has a certain bitterness, so its existence will improve the bitterness of coffee and affect the cleanliness of coffee. If we don't want a cup of espresso to have too much bitterness and a cleaner taste, then we can lay 1 or 2 round filter papers on the bottom of the powder bowl before making espresso. In this way, the filter paper can play a filtering role and block the fine powder in the powder bowl. Espresso will have a cleaner taste and reduce the bitterness.

However, it should be noted that doing so brings two disadvantages. With the reduction of fine powder, coffee will lack a certain degree of mellow degree. Because fine powder provides both bitterness and richness. So when the fine powder in the cup is reduced, the mellow degree of the coffee will also decrease. Another disadvantage is that it will shorten the extraction time, and the extraction rate of coffee is relatively not so high. Because the size of coffee powder is not uniform, during the extraction process, some fine powder whose size is the same as the bottom hole will block the holes and reduce the channels through which hot water can flow. This move will extend the extraction time of coffee and increase the extraction rate.

But if we add a layer of filter paper to the bottom of the powder bowl, then there will be nothing more that can block the filter holes of the powder bowl. As the flow channel of hot water has been restored, the flow rate during coffee extraction naturally increases. The extraction time is shortened and the extraction rate is reduced. Qianjie has made several comparisons, and the comparison is the difference between adding filter paper and not adding filter paper to the bottom of the powder bowl. The results showed that the concentration extraction time without filter paper would be several seconds longer than that with filter paper, and the extraction rate would be higher.

So if we want to reduce the bitterness of coffee by adding filter paper to the bottom of the powder bowl, then it is best to make adjustments when grinding on the premise of adding filter paper and then extracting. Otherwise, the error between the two will cause you to adjust the concentration several times, which will be a bit more than the gain.

1. Place filter paper above the powder cake If the filter paper is placed on the top layer of the powder cake, the generation of channel effects can be reduced and the coffee can be extracted more evenly.

Because there is a certain distance between the powder cake and the brewing head, the hot water has a certain impact when it falls. Although this force will not cause hot water to directly penetrate the powder cake, it will easily lift up the coffee powder on the surface of the powder cake, making it easier to generate channels and easier to extract uneven.

But if we add a filter paper to the top layer of the powder cake, we can disperse the impact of the water before it comes into contact with the powder cake, and at the same time allow the water to spread more evenly and pass through the powder bed, thereby achieving a more uniform extraction. But if you want to talk about the actual improvement effect on the extraction... Relatively speaking, it's not that big. Because the emergence of channel effects is more caused by operational problems such as improper filling and excessive amount of agglomerated coffee powder. Therefore, few people will add filter paper to the surface of the powder cake, and more people will add filter paper to the bottom of the powder bowl. Adding filter paper to the powder cake will have the effect of extending the extraction time. Because the places where hot water needs to pass through increase, the extraction time will naturally be extended. The specific extension time depends on the thickness of the filter paper. The thinner the filter paper, the less the extended extraction time will be. The thicker the filter paper, the more extended extraction time will be. This is not a bad thing, because it means we can use less powder or a coarser grind for extraction. No longer need to be limited by the standard of the powder bowl, and the amount of powder can be used more freely.

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