Coffee common sense Why is plain coffee bitter?

Today, several friends have expressed to varying degrees that they do not adapt to the bitter taste of pure coffee. I believe many people feel the same way, but why is pure coffee bitter? A seemingly simple problem has been bothering scientists for decades. Now, scientists have narrowed down their research and targeted two chemical molecules.

When you drink a cup of coffee, you actually drink a mixture of more than 30 chemicals, some of which give off fragrance, some make the taste better, and some have something to do with sour taste.

Since the 1930s, scientists have begun to separate chemicals from coffee, and many flavor-related chemicals have been separated from coffee by scientists, but no bitter chemical molecules have been found.

To make the discovery, Thomas Thomas Hofmann of the University of Technology in Munich, Germany, and his colleagues once again separated the brewed coffee. They found that the chemical molecules with the smallest molecular weight in coffee tasted the most bitter, and this part of the chemical molecules became the object of further study. After analysis by mass spectrometer, Hoffman identified one of the molecules, chlorogenic acid lactone (chlorogenic acid lactone), which is a decomposition product of chlorogenic acid (found in almost all plants).

They found that when roasting coffee beans, it triggers a chain reaction in which chlorogenic acid is first broken down into chlorogenic acid lactone, and if the baking continues, chlorogenic acid lactone breaks down into another substance: phenyllindane (phenylindanes). Although lactone will only produce mild bitterness in mild and moderate roasted coffee, the secondary decomposition products of lactone will produce strong bitterness if the coffee beans are roasted for a long time.