Why is there a small hole in the bag when buying coffee beans?

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Have you ever had the experience that when you buy coffee beans in a store, you can't help but squeeze the packaging with your hands, then suck into the hole in the packaging and say, "Wow-- this coffee smells good"? Here to remind you, in fact, this is a wrong demonstration, and will affect the flavor of coffee beans! The scientific name of this breathable hole is "one-way exhaust valve". One-way exhaust valve, to put it more colloquially, is that this valve only goes out and does not enter. The carbon dioxide emitted from roasted coffee beans will squeeze out the air and slow down the oxidation of coffee beans.

Its function: anti-inflation bag + to ensure the quality of coffee

1. Exhaust only (anti-inflating bag):

Roasted coffee beans will continue to release carbon dioxide larger than the coffee bean's own volume for a period of time. In order not to burst the coffee bag and isolate it from sunlight and oxygen, an one-way exhaust valve is installed on the coffee bag to remove the excess carbon dioxide from the bag.

2. No air intake (coffee fresh-keeping):

In addition, the one-way exhaust valve can also block the oxygen outside the coffee bag from entering the bag, preventing the coffee bean from oxidizing and causing the aroma to spread quickly, thus absolutely ensuring the flavor of the coffee bean.