Why do coffee beans produce oil?

Why do coffee beans produce oil?

Coffee beans produce oil during the roasting process because the fat inside the coffee beans is released by high temperature roasting. The following will analyze the structure of coffee beans, the roasting process and the oil release mechanism.

1. The structure of coffee beans

First, we need to understand the structure of coffee beans. Each mature coffee fruit contains two seeds, which we often call "coffee beans". These seeds are composed of the exocarp, mucilage layer (pectin), endocarp (silver skin), endosperm and pollen tube.

The main focus during the roasting process is the endosperm, which accounts for about 60% to 70% of the volume of the seed and is rich in nutrients such as carbohydrates, protein and fat.

2. Baking process

Next, let's take a look at the effect of roasting on the production of oils in coffee beans. Roasting is the process of heating raw coffee beans to high temperatures to cause chemical changes.

At the beginning of roasting, the water inside the coffee bean is heated and converted into steam, and the carbohydrates in the endosperm are broken down. This stage is called "retorting" or "initial reaction", when small cracks begin to appear on the surface of the coffee bean.

As the temperature rises, the proteins and amino acids inside the coffee beans begin to undergo acid-base reactions and Malad reactions. These reactions produce many organic substances, including the oils we are concerned about.

3. Oil release mechanism

Finally, let's discuss how oils are released from coffee beans. Under high temperature, as nutrients such as carbohydrates and amino acids in the endosperm gradually decompose, liquid oil bodies are formed under pressure.

These liquid oils seep out from the inside of the coffee beans through tiny holes or cracks, and eventually form the oils we see. This is why the surface of the roasted coffee beans will show a layer of light and oily moisture.

Summarize

In summary, the reason why coffee beans produce oil is mainly due to the decomposition of nutrients such as carbohydrates and amino acids in the endosperm under high temperature during the roasting process. These liquid oils are released from the inside of the coffee beans through holes or cracks, and form a layer of light and moist feeling on the surface.

For those who like to taste rich taste and aroma, these oils not only add flavor to coffee, but are also one of the important indicators for judging the degree of roasting and quality.

I hope that through this article I can have a deeper understanding of why coffee beans produce oil, and understand the secret better when enjoying delicious coffee.