On the shelf of the supermarket, we found a row of coffee bean bags have a small hole, both hands hold the bag and squeeze, you can smell the aroma of coffee out of the hole. Some customers will ask, does the hole in the bag not cause the beans to spoil?
First, what is a small hole
In fact, these "holes" called one-way exhaust valve. One-way exhaust valve is a functional packaging accessories, the role is the same as its name, and one-way street, only allow gas flow in one direction, never allow retrograde.
When the pressure inside the coffee bag reaches a certain level, the air can be discharged from the inside out through the exhaust valve. When the pressure inside the container is insufficient to push the valve plate open, the valve automatically closes, so that only the air inside the bag can go out, and the water vapor and air outside can not come in.
Two, why to install small holes
After roasting, the ingredients in the raw coffee beans undergo a series of chemical and physical reactions that produce gases. Coffee beans are usually bagged as soon as they are roasted and cooled in order to preserve flavor and reduce loss. Due to chemical reactions, freshly roasted coffee is very rich in carbon dioxide and will continue to emit it for a long time.
If the gas is not released, it will lead to bag swelling or even bursting, but if the gas is released by opening the package, it will destroy the sealed environment inside the bag, leading to water vapor and oxygen entering, so that the packaging will lose its significance.
The one-way exhaust valve is installed on the bag, which can expel the internal gas through the exhaust hole and prevent the external gas from entering the bag due to the pressure, so as to achieve the purpose of coffee preservation.
In addition, one-way exhaust valve is user-friendly for users, by squeezing out the smell, you can distinguish whether the flavor of coffee beans conform to their taste. However, it is not recommended to squeeze the bag, as the exhaust will also cause the coffee to lose flavor, which is not conducive to long-term retention of flavor.
