Did you know that coffee needs to be steamed?

Steaming is the prelude to coffee extraction and one of the key steps that cannot be ignored in coffee extraction.

There are two main purposes of steaming:

1. To release the gas in the coffee particles, mainly carbon dioxide. Generally speaking, the fresher the coffee beans are roasted, the more bubbling there is during pre-infusion. Darker roasted coffee beans have less water content, so they release more gas during the steaming process than lighter roasted coffee beans.

2. If the coffee particles can be evenly saturated with water after the gas is discharged, the subsequent extraction can be uniform. In short, the air between the coffee powder particles expands due to heat during steaming, and a large amount of carbon dioxide is released at the same time. A short gap layer appears between the coffee powder particles, which will provide the space required for hot water to pass through the powder layer when the water is officially poured.

【Steaming method】

Hand-brewed coffee is usually steamed in a circle from the center to the outside. It is important to note that the water should be evenly distributed on the coffee powder during steaming, and it should not be poured directly on the filter paper. What will be the effect of pouring it directly on the filter paper? The filter paper fits the filter well, and the heat has nowhere to dissipate. It will break through the coffee powder layer and form a cavity. Cold air will enter, destroying the steaming process, and the wonderful taste of coffee will not be so easy to extract.

【Key points of stewing and steaming】

1. Before adding water and steaming, make sure that the coffee powder is as level as possible in the filter or filter paper. When steaming, the force of water injection should not be too strong, but gentle. It needs to be gentle, light, fast and even, just like spring rain moistening things. Pay attention to the key points of light, soft, fast and even water injection.

2. Water temperature during steaming

You also need to pay attention to the water temperature during steaming. This is not fixed. Generally speaking, the water temperature for extracting coffee is more suitable to be kept between 83 and 92 degrees, and the water temperature for steaming should also be within this range.

Treat different beans differently and they will have different tastes at different temperatures. You need to find a method that suits you. You may not like what others recommend. If I were to make it, I would use Huang Man's medium to dark roasted premium beans. I like a slight acidity, so I would grind them to medium to coarse powder, use a water temperature of 80-82, simmer for 20 minutes, and use a water-to-powder ratio of 1:18.

If you like a mellow and rich taste, you can grind the powder to medium-fine, increase the water temperature appropriately to 88-90, simmer and steam for 40-60, and the water-to-powder ratio can be about 1:13-15

It should be noted that too high water temperature (above 95 degrees) will destroy some of the flavor characteristics of the coffee during the infiltration process of the coffee powder, resulting in a turbid taste in the extracted coffee, while too low water temperature (below 80 degrees) will lead to insufficient steaming and insufficient stimulation of the coffee activity, resulting in a monotonous and not rich taste in the extracted coffee.

3. The amount of water used for steaming

A common saying is "the amount of water for steaming should be appropriate". But what is considered "appropriate"? Many sayings rely on "looking". For example, "seeing one or two drops of coffee dripping onto the bottom seat" or "a thin layer dripping onto the bottom seat", evenly soaked, dripping without leaking, etc. I personally think that the amount of water for steaming should be enough to fully wet the powder, with the powder mound slightly moist and bulging, but not too much to form a very obvious soaking condition. This is related to the degree of grinding of the beans, and the grinding depends on the degree of roasting, the flavor of the beans, etc., so the steaming powder-water ratio can be used as one of the reference indicators but not the only one. The principle summary can be: evenly soaked, dripping without leaking. The details require more practice on your own.

Of course, this is just a technique, and there is no fixed right or wrong. Some friends also like to steam and add water powder multiplied by 3, and then pour out the bottom water. The mellowness will decrease and you can get a cleaner taste. There is also a Japanese hand-pour technique, which cancels the steaming step and starts with dripping directly, prolonging the entire extraction process, which can take up to one or two hours, and so on. So there are many ways to play hand-pour, you have to find the method you like.

4. Steaming time

The key role of steaming is to stimulate the activity of coffee powder. Having the right water temperature and the right amount of water is not enough. Time control is equally important. Steaming for too long will cause the coffee powder to soak for too long, and the flavor characteristics of the coffee powder will be fully stimulated. The bad flavor characteristics will also become active, and the good flavor components will begin to disappear after being fully soaked. If the steaming time is not enough, it will obviously result in insufficient steaming. The flavor characteristics that have not had time to fully awaken will soon begin to be extracted, and the flavor cannot be fully expressed.

[Some questions about stewing]

1. What is the correct way to steam and add water? Why do hamburgers always collapse quickly?

The burger has nothing to do with the taste. The possible reasons for its collapse are:

(1) Over-steaming

(2) Excessive water injection after steaming

(3) The beans are roasted lightly

The hamburger collapsed soon after being steamed. This may be related to the cooking technique, such as injecting water too hard to break the powder layer or injecting too much water, or too little water during steaming, and the coffee powder at the bottom of the filter cup is still dry. When water is injected again and it encounters heat, it is particularly easy to produce large "volcanic bubbles".

2. When you pour water into hand-brewed coffee for the first time after steaming, there will be a lot of bubbles. Do you need to stop pouring water at this time?

The main reason for the generation of bubbles is that the coffee is relatively fresh and contains more carbon dioxide, so a large amount of carbon dioxide gas will be emitted violently. Therefore, large bubbles are generated. Because carbon dioxide is insoluble in water under normal pressure, the most important function of steaming is to soak the powder evenly, so that carbon dioxide can be discharged and ensure uniform extraction when water is poured.

If a large amount of air is released when water is added, it may be caused by insufficient amount of water, short steaming time, or uneven steaming.

If the steaming is not done properly, even if you stop adding water, it will affect the final extraction result. Uneven extraction may result in a lower extraction rate and an unbalanced taste.

3. If the coffee beans (powder) are not fresh, will the hamburgers not be produced during steaming?

This can be used as a reference. The phenomenon of the coffee powder layer expanding like a hamburger during steaming is due to the rich carbon dioxide in the cells of the freshly roasted coffee powder, which is released rapidly and instantly in large quantities under the action of hot water.

For beans with a darker roasting degree, when the water temperature is higher, you can use the "hamburger" to judge whether the beans are fresh;

But for medium-light roasted beans, because the amount of carbon dioxide emitted is relatively small, even if they are freshly roasted beans, even if they are rinsed with very hot water, they will not have a big "hamburger". So there is no need to be too obsessed with the size of the "hamburger".

Generally speaking, about 50% of the carbon dioxide in roasted coffee beans will be released after a week. Because the smoke and fire smell is strong right after roasting, it takes about three to seven days for the carbon dioxide to be released. At this time, the beans are just finished and enter the best tasting period. About 70% will be released after a month. As the date increases, the flavor of the coffee beans will gradually disappear. Therefore, we usually recommend that it is best to drink it within a month, and try not to exceed two months. After three months, the flavor of the coffee beans will almost completely escape with the carbon dioxide, which means that the coffee beans are almost dead. This is a phenomenon that cannot be prevented by modern packaging technology, no matter how advanced it is. Of course, the beans will not go bad, but the beans are no longer young, the flavor has disappeared, and the taste is no longer the same as before.