Coffee Bags Degassing Valve: The Secret To Keep Coffee Fresh

Many friends who like to drink coffee will use sealed coffee bags. When you see a thing like a belly button on a sealed coffee bag, you can’t help but wonder what it is and what its function is. This is coffee bags degassing valve. Today, let me give you a detailed explanation.

The name of this thing is one-way degassing valve. Its function is to allow carbon dioxide to be discharged from the one-way valve while isolating external oxygen from entering to prevent coffee oxidation.

Let me explain the origin of the coffee bags degassing valve to you.

First stage:

This one-way degassing valve coffee bag similar to a belly button was invented by an Italian company in the 1960s. Its original function was to solve the problem of coffee bags bursting during the transportation of coffee beans. Its design idea is to allow carbon dioxide to be discharged from the one-way valve while preventing external oxygen from entering to prevent coffee beans from being oxidized.

Second stage:

In the era when deep roasted coffee beans were popular, coffee beans would release a lot of carbon dioxide after roasting. Plain coffee bags swelled and even burst because of the large amount of carbon dioxide released by the internal coffee beans. As a result, the one-way degassing valve became the industry standard at the time, and a one-way valve was installed on almost every reusable coffee pouch.

The third stage:

In modern times, with the popularity of lightly roasted coffee beans, the gas production of this type of coffee beans has decreased, and many coffee bean roasters have begun to think about the necessity of one-way degassing valves. However, lightly roasted coffee beans still have a degassing cycle, and a certain amount of carbon dioxide will still be produced, causing the coffee bean packaging bags to swell, so the one-way degassing valve is still widely used so far.

Let me explain the structure of the one-way degassing valve to you.

The early coffee bags degassing valve was composed of a rubber diaphragm and a liquid sealing layer, with a movable valve sheet structure inside. The outer layer is a plastic ring fixed to the top or side of the packaging bag.

When the pressure inside the coffee bags degassing valve exceeds the surface tension, the gas is discharged; the valve closes under external air pressure to prevent oxygen and moisture from entering. This design protects the coffee flavor and avoids physical damage to the packaging.

With the upgrading of material technology, the current one-way degassing valve uses polymer composite materials instead of liquid layers. The sealing function is achieved through the molecular structure design of the valve plate, so that the one-way degassing valve can isolate oxygen without using liquid media. This new type of valve plate is made of polymer composite materials through precision mold injection molding. The surface smoothness and elastic coefficient can be precisely controlled. It can directly achieve one-way barrier through physical deformation, eliminating the liquid filling link.

Why do we use this polymer composite valve plate instead of a liquid sealing layer now?

The liquid sealing layer has the risk of leaking liquid to contaminate coffee beans or high-temperature volatilization failure. At the same time, the liquid sealing process requires additional production steps and raw materials, while the solid valve plate structure is simplified and the cost is reduced. As a flexible packaging practitioner and coffee lover, I am also worried that the liquid sealing layer will leak and contaminate the coffee beans. So I strongly support coffee bean bags with valve.

Finally, I will also answer a common question about using coffee bags degassing valve.

Some coffee bean processors receive custom coffee bags from coffee bag manufacturers, especially black matte coffee bags. After filling them with coffee beans, they will find that the matte coffee bean bags are greasy, especially the position of the valve. There are several reasons for this;

1. After the coffee beans are roasted, the internal oil is discharged together with the carbon dioxide. The deeper the coffee beans are roasted, the looser the structure is, and the greater the release of carbon dioxide and oil. During the exhaust process of deeply roasted coffee beans, the oil may seep out of the surface through the exhaust valve with the gas, so you will see an oily feeling at the valve position. This is a normal phenomenon and there is no need to worry.

2. The inferior exhaust valve is not coated with silicone oil layer or liquid sealing layer leaks, causing the oil to leak out with the gas. This type of valve cannot effectively prevent the coffee oil from volatilizing to the outside. In this case, the coffee bag manufacturer should be held accountable.

3. In a high temperature environment, the oxidation of coffee bean oil is accelerated, the fluidity is enhanced, and it may passively seep out through the exhaust valve. This is also a normal phenomenon.

‌4. Coffee varieties with high oil content are more likely to leak oil, especially deep roasted ones. You can communicate with the coffee bag manufacturer to reduce the oil leakage by changing the structure of the coffee bag.

The above content is my detailed explanation of one way valve coffee bags. Finally, I recommend coffee bags with one-way valves to the majority of coffee bean processors, and choose valves with polymer composite valve plates. This is the most popular coffee beans large bag solution on the market. ‌