Can You Still Drink Coffee Beans When the Bag Inflates?

What Happens When Coffee Beans "Inflate" in Their Bag?

Here's what happened: A friend purchased a bag of coffee beans from our physical store and left it unopened until the next day, only to discover that the bag had suddenly inflated! So he left a message in FrontStreet Coffee's backend: "Can I still use this bag of coffee beans after it has inflated?"

Typically, when sealed food products suddenly experience bag inflation, there are only two possible causes: one is physical inflation, commonly known as air leakage, where the packaging bag has damage or holes that lead to insufficient vacuum inside the bag, causing it to inflate; the other is bacterial inflation, which occurs when gas-producing bacteria that may exist in the food are not completely eliminated during the sterilization process, leading to their reproduction in the food after packaging is complete, producing gas and causing the bag to inflate. However, these two factors do not apply to coffee beans, because coffee beans naturally release their own gas. The reason for the bag inflation is likely that this particular bag of coffee beans happened to meet these three factors:

1. Extremely Fresh Roast Date

As we all know, freshly roasted beans have a notable characteristic: "they contain very vigorous gases!" And this gas refers to carbon dioxide (CO2).

When we roast coffee, a large amount of carbon dioxide is produced. After roasting is complete, about half of this carbon dioxide will be hidden within the porous structure of the coffee beans. These carbon dioxide gases will gradually release over time, especially in the period immediately after roasting, when the release is at its maximum!

2. Medium-Dark Roast Level

Different roast levels of beans directly affect the final carbon dioxide content, mainly because, as we mentioned, when coffee beans are roasted darker, their internal structure becomes more thoroughly "destroyed," resulting in a more porous overall structure that can produce and accommodate more carbon dioxide. Therefore, generally, dark-roasted beans tend to release more gas than light-roasted beans! We can observe this very intuitively during the blooming phase of pour-over coffee!

3. No One-Way Degassing Valve in the Packaging Bag

This is the biggest reason for the bag inflation: the coffee bean bag doesn't have a one-way degassing valve! In the article "No!!! This hole is not for squeezing air and smelling aroma!!!" we can learn that the purpose of a one-way degassing valve is to prevent the packaging bag from bursting due to gas pressure.

Beans are immediately cooled after roasting, and after cooling, they need to be packaged for storage immediately, otherwise the flavor will be lost along with the carbon dioxide! After packaging, the beans continue to release large amounts of gas, and at this time, something is needed that allows gas to escape while preventing outside air from entering, thus both eliminating the risk of the bag bursting and preserving the flavor. And that something is the one-way degassing valve!

However, not all coffee bags come with one-way degassing valves. Sellers might want to reduce the beans' exposure to air to preserve flavor for a longer time and thus use bags without degassing valves! Bags without degassing valves combined with freshly roasted dark beans lead to the phenomenon of bag inflation! "But every bag of coffee beans sold by FrontStreet Coffee comes with a degassing valve, so this shouldn't happen. Could it be a sample?" With this question in mind, FrontStreet Coffee replied to the friend. And this is how the friend responded: "Is there a possibility that I bought it from someone else..."

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FrontStreet Coffee

No. 10, Bao'an Qianjie, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province