What does under-extracted coffee taste like? What are the characteristics of over-extracted coffee? How to tell if coffee is over-extracted or under-extracted?

Qianjie found that many friends always encountered such a problem when they first started learning to make coffee: they found that the coffee they brewed was not good, but they couldn't tell what was bad.

Reasonably, if we want to make a cup of coffee well, in addition to learning the underlying logic of brewing and mastering the correct extraction parameters, we also need to know how to identify the extraction of coffee.

Because the bad taste of brewed coffee is mainly caused by the two conditions of "insufficient extraction" and "excessive extraction"(Qianjie refers to the effect of extraction here), and their characteristics and solutions are different. Only by knowing what situation makes the coffee difficult to drink can we find corresponding improvement plans and finally make a delicious cup of coffee.

Therefore, whenever a friend reports that the coffee poured out is not good at Qianjie stores, Qianjie will always ask everyone to explain the specific characteristics of the coffee's bad taste, and then give corresponding improvement suggestions. It doesn't matter if you don't know. Today, Qianjie will come to share with you how to distinguish the extraction situation of coffee!

What is excess? What is insufficient extraction? Friends who have learned coffee theory will know that the definition of insufficient and excessive extraction mainly comes from gold cup extraction. In the Gold Cup Guidelines, an extraction rate of 18% to 22% is considered a reasonable extraction range for a cup of coffee to taste good. An extraction rate below 18% will be judged as insufficient extraction, while an extraction rate above 22% will be considered excessive extraction. But making coffee is after all a daily thing. Even experienced baristas will not take out a concentration meter to measure whether the concentration of coffee is up to standard, let alone ordinary, newly-started coffee lovers.

And the most important thing is that the Golden Cup Guidelines are not absolutely correct. Coffee within the extraction range of the gold cup may not be good, while coffee liquor beyond the extraction range of the gold cup may not be bad. Why? Because it is related to the quality of coffee beans. First of all, we need to know that the soluble substances in coffee beans only account for 30% of the weight of the beans. In this 30%, there are not only high-quality flavor substances that we like, but also some unlikable substances. Many times we think coffee tastes bad because these unflattering substances have the upper hand in the cup.

The proportion of these substances in coffee beans is mainly affected by the quality of coffee beans. The variety of coffee beans and planting environment are all among the factors that determine the quality of coffee. When the quality of coffee beans is higher, there are fewer undesirable substances, and vice versa. What does Qianjie want to express? That is, if the quality of coffee beans is high enough, even if we dissolve a large amount of its soluble substances and the extraction rate exceeds 22%, the coffee will not necessarily be difficult to drink, because there are not many unpleasing substances in its body; conversely, if the coffee contains many unpleasing substances, even if the extraction rate falls within the range of a golden cup, it will not be good to drink.

Of course, this is also related to differences in the dissolution of substances. Since the extraction rate is only an average value, it cannot determine which substances in coffee are good and which are not good. Therefore, instead of relying on instrument measurement, Qianjie recommends that everyone combine reality and judge the specific extraction situation through the characteristics of coffee taste.

What are the manifestations of insufficient extraction? Combined with the above, Qianjie believes that everyone has a certain understanding of insufficient extraction and excessive extraction. Insufficient extraction means that only a small amount of flavor substances in the coffee are carried out by the water. For example, coffee has 30% soluble matter, but we only dissolve 10% or 15% by brewing. Generally speaking, under-extracted coffee will have one or more of the following three negative characteristics. Weak flavor: Since many flavor substances have been extracted before they can be dissolved, coffee that is not extracted enough will usually have negative characteristics of weak aroma and weak taste.

Very water-sensitive: Because there are not enough flavor substances in coffee, when the powder liquid is relatively small, the concentration will be slightly insufficient. Coffee will have a strong watery feel and the taste is very thin. Sour and salty: Sour, salty, sour, etc. are all negative manifestations common in under-extracted coffee. Because the dissolution rate of coffee's flavor substances will be affected by the molecular weight. Light-weight molecules related to acids dissolve fastest and dissolve in large quantities at the beginning; sweetening molecules are second; bitter substances have the largest molecular weight, so they dissolve slowest.

Many friends stop extracting the sweet and bitter substances before they have been sufficiently dissolved, so there are only sour substances in coffee that have been dissolved in large quantities at the beginning. Since there is no balance of other flavors, sourness dominates the family, and coffee may taste very sharp sourness. You may even get a distinct salty or astringent feeling from coffee that is not sufficiently extracted. When extracted properly, the salty and astringent taste of coffee will generally be concealed by other flavors, which is generally difficult for us to detect. But when the extraction is insufficient, we can taste it from the coffee because of the lack of other flavors to hide them.

If we taste any of the above three negative manifestations from coffee, then there is a high probability that this cup of coffee is under-extracted. There are many factors that lead to insufficient extraction, such as too rough grinding, too low water temperature, too short time, too little water, and even insufficient stirring frequency can cause insufficient extraction. Because the solution was the same as that of Gao Cui, Qianjie put it last and said it together.

What are the manifestations of excessive extraction? Over-extraction is much easier to distinguish, because over-extraction means extracting too much, dissolving too much of the unlikable things in the coffee, such as macromolecules with slower dissolution rates.

The main manifestation of over-extracted coffee is obvious bitterness, dryness, or some miscellaneous flavors such as wood and straw. Because we are all sensitive to these manifestations, many times we can easily identify that coffee is over-ripe.

The reason for over-extraction of coffee is the opposite of insufficient extraction, which is the extraction efficiency is too high. For example, grinding too fine, water temperature is too high, time is too long, stirring is too strong, etc. However, in most cases, over-extraction is caused by too long extraction time.

How to improve under-extraction and over-extraction? The reason for over-extraction and insufficient coffee is nothing more than too high or too low the efficiency of the parameters, so we only need to reduce the extraction efficiency when the coffee is over-extracted, and increase the extraction efficiency when the extraction is insufficient. However, the difficulty is that with so many parameters affecting extraction, how should we choose the objects to adjust?

In fact, it's very simple. We just need to fix a few of the parameters and then adjust one parameter. Water temperature, grinding, time, and water quantity are the four major parameters that affect coffee extraction, and only the value of grinding degree is invisible, so our fixed objects can be water temperature, time, and water quantity, and then grinding is adjusted as the only variable. Take the former street as an example! Assuming that Qianjie brewed a lightly roasted coffee bean, Qianjie will use a water temperature of 91 - 93°C (86 - 89°C for deep roasting), a powder-to-water ratio of 1:15, and two minutes to brew it, and choose a commonly used scale for grinding. If the washed out taste is characterized by insufficient extraction, adjust the grinding degree. If over-extraction characteristics appear, the grinding is coarse.

In this way, we can quickly find parameters that suit the current coffee beans, and at the same time correct the taste of the coffee to make it taste better. But this method can only make a preliminary improvement. In addition to the parameters that will affect the extraction and taste of coffee, there are many other factors that will affect coffee, such as the problem of fine powder. For more complicated situations like these, you can move to the article "Portal" to understand, and we won't go into it too much on the street.

- END -