Do oils on coffee beans grow over time?

The oils on coffee beans refer to the oils on the surface of coffee beans, which grow over time. This oil is an important part of the unique flavor and aroma of coffee and is essential for making a strong and delicious cup of coffee.

First, we need to understand why oil forms on coffee beans. When coffee beans are roasted, the internal moisture is gradually removed, and due to chemical reactions under high temperature, the internal substances are converted into gas and liquid. Some of the liquid will seep out through tiny holes to the surface of the beans and quickly solidify in the air to form oil.

Over time, the amount of grease formed on these surfaces will gradually increase. On the one hand, during storage, due to contact with air and environmental factors such as light and humidity, the originally small amount of grease on the surface will continue to diffuse and accumulate; on the other hand, the high temperature generated during the cooking process will also cause more internal substances to transform into liquid and flow to the outer surface.

The oils on coffee beans not only grow over time, but also affect the flavor of coffee. These oils are rich in aroma substances, such as phenols, aldehydes and ketone compounds. When these oils are formed and gradually accumulated during the roasting process, they interact with other chemicals inside the coffee beans and release a unique and rich aroma through volatilization.

However, it should be noted that too much oil may also have an adverse effect on the quality of coffee. When a large amount of oil accumulates on the surface, over-extraction and bitter taste are prone to occur during roasting or brewing. Therefore, when storing and using coffee beans, it is necessary to control their contact with environmental factors such as air and humidity to slow down the growth rate of oil.

In short, as time goes by, the oil formed and accumulated on the coffee beans will gradually increase. This change not only makes the coffee have a richer and more charming aroma, but also requires us to pay attention to controlling the growth rate of oil when storing and using coffee beans to ensure the quality of coffee.