What changes will occur to coffee beans after they are stored for a long time?

Roasted coffee beans will change over time. Roasted beans will lose their aroma after being left for a certain period of time, and the taste may also become bad. The process of coffee beans slowly losing their aroma is called deterioration.

However, whether coffee beans are deteriorated is a subjective judgment of the coffee maker and the coffee drinker. Which one tastes better, freshly roasted coffee beans or coffee beans that have been stored for a year? First of all, the flavors of the two are definitely different. If you judge it literally, everyone will definitely choose the former. People who choose the latter think that the coffee beans have been stored for a year before the taste is just mature. Some people don't like to brew coffee with freshly roasted coffee beans. Yes, this may be a bit disappointing for the processor.

So, why does the taste of coffee beans change? The change in the taste of coffee beans is actually a change in aroma. Freshly roasted coffee beans will release gas (carbon dioxide), which will take away the aroma of the coffee beans, and then the remaining aromatic components will begin to react chemically. The total amount of aroma is decreasing, and the quality of the aroma is also decreasing. When the pleasant smell slowly disappears, we will notice that the coffee beans have deteriorated.