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What are the "round holes" in the bag of baked coffee powder for? (cold knowledge)

Published: 2026-08-25 Author: World Gafei

Last Updated: 2026/08/25, Wen / Ziquan, as a newcomer who is addicted to coffee, I recently bought a batch of roasted coffee beans. It is found that there will be a hard, round part with small holes on almost all the packages. Is the breathable hole for me to smell the coffee? The scientific name of the small hole is the one-way valve. To put it more popularly, this air valve is only out and not in. What it does:

Wen / Ziquan

As a newcomer who is addicted to coffee, I recently bought a batch of roasted coffee beans. It is found that there will be a hard, round part with small holes on almost all the packages. Is the breathable hole for me to smell the coffee?

The scientific name of Xiao Kong is "one-way valve".

One-way valve, to put it more popularly, that is, this air valve only goes out and does not enter.

Its function: explosion-proof bag + ensuring the quality of coffee

Only outgassing (explosion-proof bag): coffee beans will continue to release carbon dioxide several times the volume of coffee beans for a period of time after roasting. In order not to let the coffee packaging burst and be isolated from sunlight and oxygen, an one-way valve aluminum foil bag is designed to discharge excess carbon dioxide out of the bag.

No air intake (coffee fresh-keeping): in addition, the one-way exhaust valve can also block the outside oxygen from entering the bag to prevent the coffee bean from oxidizing and causing the aroma to spread quickly, thus absolutely ensuring the flavor of the coffee bean remains unchanged.

Additional function: smell fragrance

Of course, when you buy coffee, you can squeeze the bag and smell the fragrance through the hole.

How to keep the coffee bag after it is taken apart?

Freshly baked coffee beans, it is best to put in an one-way valve bag, because it is still exhaust, it can be kept fresh in a glass sealed jar after 48 hours.

If there are no glass cans, when the coffee beans are opened or sealed, drain the remaining air from the container as much as possible to reduce the excessive contact between the coffee beans and the air. Or pack it into small bags and squeeze out the air for preservation.

Temperature requirements for coffee preservation

Try not to put it in the refrigerator and keep it at room temperature.

The air in the refrigerator is cold and dry, so it is easy to evaporate the moisture in the coffee beans and lose the aroma of the coffee.

If you keep it in the refrigerator, you should pay attention to:

1. The packing should be absolutely sealed.

two。 Do not unpack until you return to room temperature (otherwise the coffee beans that have just come out of the refrigerator will condense water vapor in the air, and these small droplets will make the coffee powder into lumps, easily leading to uneven brewing of coffee. The rate of microorganisms and oxidation at room temperature is quite appropriate.

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