There's foam coming out of the hand coffee. What's going on? How good or bad is the hand-made coffee foam?

Guide reading

When brewing hand-brewed coffee, it often feels "cured" because it can make rich coffee foam. So I wonder if you have ever thought about where the coffee foam comes from and what effect it has on the brewing flavor.

Coffee foam

Friends who have brewed by hand must have experienced that in the first stage of water injection after steaming, there will be rich bubbles. The coffee foam in the first stage of water injection is called golden, while the coffee foam in some sections will slowly turn white and become thin.

In order to uncover the mystery of this bubble, Qianjie decided to take a look at the floating foam while brewing. Qianjie normally uses three-stage style to cook Yega Xuefei (medium and shallow baked) and Brazilian Queen's Manor Yellow bourbon (medium and deep baked) respectively. And after the second stage of water injection, use a spoon to fish up the coffee foam on the surface.

When cooking, we can see that the medium-to-light baked Yega Chuefei foam is obviously thinner and lighter than the medium-deep baked yellow bourbon.

When we take out the foam on the surface and observe it, we can see that it is composed of three parts: coffee oil, very coarse powder and very fine powder. Ultra-fine powder can be especially reflected in medium-and deep-roasted coffee.

When comparing the two groups, we can see that the initial foam appears dark brown or golden yellow because the very coarse powder has a low degree of water absorption and light weight, so it will float on the surface at the beginning, and with continuous water injection and flushing, the very coarse powder gradually absorbs water and becomes heavier, and then sinks to the bottom, and all foam liquid foams will gradually fade and whiten. On the other hand, some ultra-fine powder itself is of small quality and is easy to be absorbed and noted by coffee foam and float on the surface.

What does foam taste like?

After a dead taste of coffee foam, the taste can obviously feel the roughness of coffee particles, and its taste is not as negative as imagined, with slight woody, roasted and other miscellaneous flavors, and it is not too repellent to taste alone. but if these flavors are certainly negative in a cup of coffee.

So since the flavor of coffee foam is so negative, will it be better to scrape them off during brewing? Use the Queen's Manor Yellow Bourbon coffee beans for the previous street to boil the normal version and the second section of water respectively, scrape off the foam and then inject the last section of water. The front street found that the cup of coffee that had shaved off the foam was obviously thin in taste and felt a change in flavor.

Actually, coffee with foam is better than coffee without foam.

If you have brewed stale coffee beans, you will observe that there is little or no foam on the surface of the coffee. Then the fine powder floating on the surface will sink to the bottom to participate in more thorough extraction, and some miscellaneous flavors and woody flavors will be extracted into the coffee, coupled with the fine powder sinking to the bottom will clog the water hole, causing excessive extraction risk. This is why stale coffee beans are easy to wash out of wood and miscellaneous flavor.

The foam adsorbs the fine powder to show a bad flavor, but they always float on the surface of the filter cup, and the coffee liquid flows up and down to the right, so it is difficult for the negative flavor to flow into the next pot of coffee. More traditional Japanese schools believe that foam is the source of bitterness, so in the last stage of brewing, a large current will wash up the coffee foam, and then cut off the bitterness brought by the foam.