How to tell if the bitterness of coffee is over-extracted or over-roasted? How to control the parameters of hand-brewed coffee?

Yesterday, Qianjie received a very interesting question, from a guest friend, he asked Qianjie, he obviously made a river closure operation, but why the coffee is still so bitter?

Well, this is another friend misled by interception. In fact, the reason is very simple, because the end of the extraction is not the main source of bitterness. And bitterness is also divided into many types, different types of bitterness will bring people completely different feelings. So today, Qianjie will share the reasons why coffee tastes bitter, as well as the corresponding circumvention schemes.

The bitter substance of the coffee bean itself is often caused by the "bitterness of the coffee" we mentioned. Coffee bean itself is a kind of agricultural product with bitter taste. Chlorogenic acid, caffeine and trigonelline in beans are the main contributors to bitter taste. But in addition to bitter substances, coffee beans also have sour, sweet, salty and other flavor substances, so we will not extract all the bitter substances from the very beginning.

Acid and sweet substances are small molecular substances with fast dissolution rate, so at the beginning of extraction, acid and sweet substances will be a large number of dissolved objects, while bitterness belongs to macromolecular substances, so its dissolution rate is very slow. It's slow, but it runs through the whole process. It is constantly released from the extraction to the end, and because it is slow, when the sweet and sour substance is released, it is still released, but when the extraction process reaches this point, it still does not stop. all the bitterness and miscellaneous flavors extracted will be added to the coffee, and the coffee will have an obvious bitter taste! And this is what we commonly call "Guojie". It happens that this node is at the end of the extraction, which leads to the tail segment being criticized as the main release node of bitter substances. So we can know that the reason for intercepting the river is not because the tail section will extract bitterness. But because the extraction of coffee has reached a critical point, after the extraction, there will be only bitter taste, astringent taste and miscellaneous taste, so we will use the closure operation. Generally speaking, the application of river closure is either because of the sudden blockage, the extraction efficiency is raised, or the liquid weight of the planned extraction scheme is reached, and it is no longer necessary to continue the extraction.

Speaking of which, we must have understood why the coffee tastes bitter! "over-excellence" is the initiator of the problem. The extraction efficiency will be greatly improved if the grinding is too fine, the fine powder is too much, the water temperature is too high and the extraction time is too long. So if you brew coffee with obvious bitterness frequently, you should pay attention to the extraction parameters during brewing and correct them to reduce the efficiency of extraction, so as to reduce the appearance of bitter taste.

In addition to the bitter taste carried by the coffee bean itself, the roasting process also adds a certain amount of bitter substance to the coffee bean. At present, the coffee beans sold on the market are mainly divided into two kinds of roasting degree, deep roasting and shallow roasting. The lighter the baking degree of the beans, the more sour substances retained in the beans themselves, and the high proportion of sour substances will make the coffee mainly sour; while when the beans are roasted more deeply, the sour substances will decrease with the deepening of roasting, and the bitter substances will increase with the deepening of roasting, less sour and more bitter, so bitterness will become the dominant taste.

What we need to know is that the "bitter" mentioned here in Qianjie is not like an exquisite, hard-to-swallow bitter taste. Instead, it is the bitter aroma of mellow flavors such as caramel and chocolate brought about by the caramel reaction that has been baked for a long time. If the coffee beans have this flavor when they are roasted, these flavors will be added to the coffee during the extraction process. Although this is a positive expression of flavor, but for friends who do not like bitterness, this kind of bitterness is not much different from exquisite bitterness. So in this case, it is best to buy coffee beans, try to choose some light roasted beans, the flavor description is floral, fruit acid type beans. They are rich in sour substances, so it is not so easy to extract bitter substances. -END-