Is the oil from coffee beans not fresh? Is the oil leakage of coffee beans normal? How to brew so as not to be bitter?

It is said that history is a reincarnation. 40 years ago, coffee beans were shiny black and bright, but now they have become coffee beans. Is it not fresh and there is a problem?

Front Street today to explain why some coffee beans surface oil, some do not. We often find that oily coffee beans are darker in color, while dry coffee beans are lighter in color (light brown). So the main reason for coffee beans out of oil is the degree of roasting coffee beans.

Coffee beans produce a lot of carbon dioxide when roasted. Generally, the deeper the roasting degree, the richer the carbon dioxide produced in the beans. When roasted, most of the abundant carbon dioxide in the coffee beans will be excreted in large quantities within 3-4 days, and the oil will also be released from the surface with the release of carbon dioxide. The deeper the baking, the more oil seeps out.

In the past to the second explosion as the node of the time, coffee beans are almost all dark black "Italian roast", just out of the oven, coffee beans do not have obvious oil, in 1-2 days after the placement, oil will quickly seep out, making the whole coffee beans shiny. The current "Japanese deep baking" basically shows this state. Coffee roasting is generally not that deep anymore. So it's hard to see shiny coffee beans these days (the only ones you can see now are coffee beans from a well-known coffee chain, Italian coffee beans, Japanese roasted coffee beans).

The second explosion is densely baked, and there is no grease on the surface of the coffee beans roasted in the former street coffee. Only Indonesia's Mantenin, Jamaica's Blue Mountain, and Italian blended coffee beans are roasted deeply, and there will be slight oil. Other lightly roasted coffee beans basically do not appear oil.

Some friends say that Costa Rica coffee beans will also have a slight oil phenomenon. In fact, this is a phenomenon of honey processing coffee beans. Honey treatment Because the pectin layer is not peeled off, the pectin will be thicker in the center line and both ends of the coffee bean, and it is easy to leave sugar. After the caramelization reaction during roasting, those sugar will caramelize, and the center line and both ends will be darker than the bean body. Sometimes there will be a reflective feeling.

Is it true that pre-roasted coffee beans are not fresh? There is indeed such a phenomenon, but not absolute, some coffee beans in the exhaust will exude oil, so that coffee beans appear a kind of "oil" flavor, so that coffee beans lose their original flavor. However, it has been difficult to explain clearly to consumers what is light roast, medium roast and medium light roast. Coffee beans are processed in an increasingly diverse way, and new anaerobic treatments are emerging that make it impossible to distinguish them in the original way. For example, in the flower moonlight coffee beans, its flavor performance for sweet strawberry jam, rose, wine chocolate flavor, in everyone's definition is what baking degree? After 4-7 days of cultivation, this coffee bean will exude a small amount of oil in the center line of the bean. But there is no "grease" smell, oozing grease is a normal phenomenon. Therefore, it is easy to misjudge whether coffee beans are not fresh by oil extraction, or use the old method to see whether steaming expands, and then taste whether it is more reliable.