Why is hand-made coffee steamed by hand? is it all right to make coffee by hand?

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We all know that coffee beans will continue to emit carbon dioxide and volatile aromatic substances after roasting. Whether coffee beans are used for Italian or hand flushing today, carbon dioxide must be fully emitted to avoid being hindered by exhaust in the extraction process. The former extraction is incomplete (insufficient extraction). In order to make the follow-up hot water extract soluble substances in coffee smoothly, steaming is very important!

A small amount of hot water is used to trigger the emission of carbon dioxide from the ground coffee particles as soon as possible, so that the hot water can smoothly enter the gap between the coffee particles, take out all kinds of soluble substances, and dissolve and hydrolyze.

For hand flushing, steaming is particularly important without the help of 9 bar atmospheric pressure in the Italian coffee machine to help you get a better extraction ratio during the previous stage of extraction.

Then someone asked, if I am not stuffy and steaming, can I make the extraction return to the normal proportion for a longer time, theoretically, but also prolong the brewing time, enhance the concentration of the coffee and dissolve more chlorogenic acid, quinic acid and other substances, causing the coffee to become sharp and astringent.

So what do you need to pay attention to in steaming?

The first is "water". A small amount of hot water is applied to discharge carbon dioxide, so the amount of water can be controlled to 2 times the weight of coffee powder. For example, for 20 grams of coffee powder, we can use 20 to 40 grams of water to steam.

Then there is the "time", which depends on how deep the coffee beans are roasted and how long they have been preserved. Generally speaking, the roasting degree of coffee that is often used to make coffee by hand is what consumers call shallow roasting, which is about 75 to 60 of the Eagram Agtron index. When carbon dioxide emissions are stable, it is about a week after baking. The longer you put it, the more carbon dioxide will escape, and after about the fourth week, the carbon dioxide emissions will become thinner. When brewing, if you use coffee beans within 2 to 4 weeks, the steaming time is about 20 to 30 seconds after water injection, and then you can continue to fill water to complete the brewing process.

But what if you encounter coffee beans that have been stored for a long time?

Under normal circumstances, fresh coffee particles will cause the coffee powder bed to rise up into a hill because of exhaust. If it is stored for a long time, it will rise slightly or not at all. At this time, it should be noted that your steaming time should not be too long. The steaming time should be halved. If you steam in accordance with the time of 20 to 30 seconds, it will make the coffee powder bed glue and condense. As a result, the second water injection can not be extracted smoothly or even because the water can not pass through the powder bed, the water flow directly through the filter paper, the astringent taste of coffee products becomes very obvious, and the concentration is low, the taste will become light and sour.

I hope that through this article, we can understand the necessity of hand steaming and adjust the steaming time according to the storage time of coffee. I wish you all can enjoy a cup of delicious hand-brewed coffee every day.