Parsing | Why does the coffee we drink taste bitter?

There are two main reasons for the bitterness of coffee:

Roasting of coffee beans and brewing of coffee.

To the surprise of many people, coffee beans themselves are not bitter, here coffee beans refer to raw coffee beans. The bitterness of coffee beans is caused by the process of turning raw beans into ripe beans, that is, the roasting of coffee beans. Raw coffee beans contain a component called chlorogenic acid, which is produced by plants in response to environmental changes and is found in many plants. The bitter stool of coffee is related to chlorogenic acid. Chlorogenic acid is composed of quinic acid and caffeic acid.

During baking, chlorogenic acid is decomposed into quinic acid and caffeic acid, and coffee beans will experience bitterness (from quinic acid) and astringency (from caffeic acid). At this time, if continuous baking, quinic acid into quinic acid lactone (taste bitter), caffeic acid into vinyl catechol vinyl catechol is not only bitter, but also astringent.

There is another reaction of chlorogenic acid in the baking process to form chlorogenic acid lactones. Chlorogenic acid lipids are bitter and sweet, and there will be layers of bitterness to sweetness when tasting. Therefore, some people call chlorogenic acid lactone a pleasant bitter taste, while vinyl catechol is a bad bitter taste. The bitter taste of coffee beans produced by roasting, according to the characteristics of raw beans, grasp the firepower and time of roasting. Generally speaking, the longer and deeper the baking time, the more bitter the beans.

Coffee

The preference for the roasting degree of coffee beans in each country often varies from region to region. It is said that the baking degree in Italy is getting deeper and deeper from north to south, and Rome in the south prefers the bitterness of baking to Milan in the north, while the roasting of coffee in the United States is getting lighter and lighter from west to east, and the coffee on the west coast is darker than that on the east coast.

In addition to the roasting of coffee beans, the water temperature, time, grinding degree of coffee powder and the ratio of powder to water will also affect the bitterness of coffee.

The brewing of coffee is actually the process of coffee extraction.

Thousands of soluble substances in coffee powder are dissolved in water, which involves the dissolution rate of coffee powder.

There are three main factors affecting coffee extraction:

Water temperature, coffee powder grinding degree, time.

When the water temperature is higher, the faster the extraction, the higher the dissolving rate of coffee powder.

The finer the coffee powder and the larger the contact surface with water, the higher the solubility.

The longer the extraction time is, the higher the solubility is.

In addition to the above factors, the cooking method will also have an effect on the extraction. For example, the use of Italian coffee machine, the higher the pressure, the faster the extraction, the higher the dissolution rate; when using hand flushing, the flow speed will also affect the extraction rate.

The higher the dissolution rate, the more substances extracted from the coffee powder, the more miscellaneous flavors in the coffee, and usually the thicker and bitter taste.

Generally speaking, the first half of coffee extraction is aromatic substances, coffee oils and so on, while the substances extracted in the second half taste astringent.

So it is not that the higher the dissolution rate, the more complete the extraction, the better the coffee. How to effectively extract the front segment of coffee and reduce the impact of the aftertaste on coffee is the task of many baristas.