Sharing of hand punching skills: the necessity and parameter adjustment of "stuffy steaming"

For professional baristas, please follow the coffee workshop (Wechat official account cafe_style)

In the process of learning hand flushing, in addition to the conventional circular water injection method and water cut-off method, the most common term asked by many students is "steaming" and put forward all kinds of strange statements. I think it is necessary to write an explanation about it to explain one or two.

First of all, 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 style or hand flushing today, carbon dioxide must be fully emitted to avoid being hindered by exhaust in the extraction process, thus making the front extraction incomplete (insufficient extraction). In order to make the follow-up hot water extract the 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 quickly 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 a student asked, if I am not stuffy and steaming, can I make the extraction return to the normal proportion for a longer time? theoretically, yes, but it also prolongs the brewing time, enhances the concentration of the coffee and dissolves 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". Today, we apply a small amount of hot water to discharge carbon dioxide, so the amount of water can be controlled to 2 times the weight of coffee powder. For example, 20 grams of coffee powder, we can use 20-40 grams of water to do steaming.

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 students and consumers are brewing, if they use coffee beans within 2 to 4 weeks, the steaming time is about 20 to 30 seconds after water injection, and then they can continue to inject 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.

# the text of this article is painstakingly created by OWL, and the copyright is owned by OWL. Please indicate the source and website for reprint.

By │ Bruce Bruce

# founder of Owl Forest Coffee

# American Fine Coffee Association SCAA Bean Baker # European Fine Coffee Association SCAE Bean Baker # European Fine Coffee Association SCAE Gold Cup Brewer

# SCAE sensory development of the European boutique coffee association # City & Guilds international baristas in the UK