How long the coffee steams! Why does it take 30 seconds to steam hand-brewed coffee?

"What is the difference between a coffee steamed for 30 seconds and a coffee steamed for 60 seconds? "This was a question raised by a friend on Qian Street yesterday. Not to mention, this question is indeed interesting!

As we all know, steaming is a regular part of hand-brewed coffee. The specific operation is that before the formal water injection, we will inject a small portion of hot water in advance to wet the powder layer and pause for about 30 seconds. In the production of coffee, such an intervention can greatly improve the efficiency of coffee extraction and increase the dissolved coffee substances. Simply put, it can make the coffee that comes out more delicious. Qianjie has conducted a special test for this. When the coffee beans and extraction parameters used are the same, the extraction rate of coffee steamed for 30 seconds will be much higher than that of coffee without steaming. The difference in taste can also allow novice Xiaobai to distinguish the two with one bite. It is enough to see that the impact of steaming cannot be underestimated on hand-brewed coffee.

"But if we follow Qianjie's statement above, wouldn't it mean that the effect of steaming for 60 seconds would be better than that of 30 seconds? "This is the reason why our guest friend raised the opening question yesterday. Very good! Since a friend has asked questions sincerely, then I will come from Qianjie to make a comparison of brewing and brewing to share with you what kind of difference there is between coffee steamed for 30 seconds and coffee steamed for 60 seconds.

Brewing Experiment In this brewing, Qianjie will use three coffee beans with different freshness to compare! They are fresh coffee beans that are only 3 days away from roasting time, coffee beans that are 15 days away from roasting time, and coffee beans that are 30 days away from roasting time. Then Qianjie will use each coffee bean to brew two pots of coffee. One pot will steam for the regular 30 seconds, and the other pot will have 60 seconds. Finally, the extraction rate and taste will be measured to compare the differences between them. Since the baking degree of the three beans is medium and light, other parameters except the steaming time are the same! The following: powder amount used: 15g, boiling water temperature: 92°C, powder water ratio: 1:15, degree of grinding: 10 scale of Ek43, 75% sieving rate of No. 20 screen, grinding and boiling method of fine sugar: Three-stage auxiliary equipment: drip filter shower (reduce the impact of artificial cooking)

We directly skip the introduction of the brewing process. After the coffee is brewed, we will taste and measure the extraction rate. The final results are as follows: Baking 3-day group: the extraction rate after steaming for 30 seconds is 19.95%; The extraction rate after steaming for 60 seconds is 20.33%; Baking 15-day group: the extraction rate after steaming for 30 seconds is 20.21%; the extraction rate after steaming for 60 seconds is 20.49%; The extraction rate after steaming for 60 seconds is 20.49%; Baking 30-day group: The extraction rate of steaming for 30 seconds is 20.37%; the extraction rate of steaming for 60 seconds is 20.58%. It can be seen that no matter which group, the extraction rate of steaming for 60 seconds will indeed be higher than that of steaming for 30 seconds., but the gap between them will be smaller than everyone thinks and not much. The same is true for the difference between flavors. Coffee steamed for 60 seconds will taste slightly stronger than that steamed for 30 seconds, but not too strong.

Although there is a difference of 30 in steaming times, the experimental results of "0 seconds and 30 seconds" and "30 seconds and 60 seconds" can be said to be quite different. The comparison of the former can be accurately distinguished by Xiaobai under a blind test, while the blind test of the latter requires careful tasting by the barista to distinguish the two (except for the first group, which will be more obvious). The reason is that the effect of steaming we need has been almost completed in a short 30 seconds.

Why does hand-brewed coffee need to be steamed? The main reason why the addition of steaming can improve the extraction rate of coffee is that it can expand the coffee powder and emit carbon dioxide accumulated during the roasting process.

Coffee extraction is carried out through concentration gradient differences! When hot water comes into contact with coffee powder, the flavor substances in the coffee powder will be transferred to water with lower concentration due to the difference in concentration. In this process, a problem we need to face will arise, that is, water cannot immediately enter the inside of the coffee powder and come into contact with the flavor substances inside. Because carbon dioxide in the coffee powder is quickly discharged after coming into contact with hot water, this will slow down the speed at which hot water reaches the inside of the coffee powder. If a large amount of water is extracted before the water has completely wetted the coffee powder, there will be a lot of hot water that will not be able to fully extract the flavor substances in the coffee.

Therefore, we need to steam to complete carbon dioxide emissions. By using a small part of hot water to pre-moisten the coffee powder, carbon dioxide is discharged and the hot water is immersed into the inside, so that subsequent hot water can better dissolve the flavor substances in the coffee powder, making the extraction more uniform and efficient. However, the time it takes for hot water to complete the job will change depending on the status of the coffee beans and the parameters used. I believe that some friends have found from experiments shared on the street that the difference in the extraction rates of the two pots of coffee compared in the first group was the largest, and then the gap between the coffees became smaller as they went on.

This is because the coffee beans used in the first group are the freshest and have the most carbon dioxide content. They require longer steaming to release the carbon dioxide in the coffee powder, so the difference between the two pots of coffee in the first group will be larger. In addition, parameters such as baking degree, density, and extraction parameters will affect the time required for steaming. However, it would be too difficult for a novice to compare them one by one and then find the right steaming time. Therefore, generally the Front Street Association recommends that novices use "30 seconds" to steam first. This is a relatively safe steaming plan. It will not be too short to exhaust enough, nor will it be too long to waste time. As long as the right parameters are used, this time can still allow the coffee to be fully extracted.

And when we can steadily brew a cup of delicious coffee, it will not be too late to start learning advanced knowledge. Of course, if you need it now, you can directly click on "Portal" to jump to understand ~

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