What is the performance of insufficient coffee extraction? What is the reason for the acidity of coffee? The hand coffee is too sour.

Guide reading

In the last article, Qianjie explained "how overextracted coffee behaves in flavor", and this issue of barista training goes on to discuss how underextracted coffee will behave!

What is insufficient extraction?

According to SCA's gold cup extraction theory, 18-22% of the water-soluble substances in coffee are good flavors. Therefore, when we brew coffee, the extraction rate is guaranteed in the range of 18-22%. Then the lack of extraction is actually that the extraction rate does not reach the lower limit of 18%.

What is the manifestation of insufficient extraction?

Sensually, the lack of coffee extraction can be divided into the following situations:

① has a sharp acidity.

The most obvious manifestation of insufficient extraction of coffee is acidity. Because in the case of normal extraction, the first release is sour substances, then sweet molecular substances, and finally bitter substances. Therefore, if the coffee is under-extracted, the sour substances in the first stage are basically extracted, while the sweet and bitter substances are not extracted. Therefore, the overall extraction rate is slightly lower, a cup of coffee lack of sweetness and bitterness neutralization, will appear sharp and exciting acidity.

② is salty.

The salty taste of coffee comes from minerals and inorganic compounds in coffee beans. In fact, these salty substances are also extracted into the coffee liquid during normal brewing, and we can't feel the salty taste in the coffee because the sweetness masks the salty taste (salty and sweet are mutually reinforcing). When the sweetness is not enough (extraction is not enough), when the sour taste is too strong, the salty feeling will be highlighted.

The remaining rhyme of ③ is empty.

Another manifestation of underextracted coffee is its short aftertaste, which makes the sensory experience of the whole coffee incomplete.

So how can we avoid insufficient extraction?

The concentration of ① is high and the extraction rate is insufficient (rich sour and salty)

This situation is probably caused by the fact that the ratio of powder to water is too small, that is, more coffee powder is made with less water, which leads to the inefficiency of the overall extraction of water, resulting in only the first half of the coffee flavor can be extracted. while the flavor of the second half is still in the coffee powder, and because the ratio of powder to water is too small, it leads to a strong and sour flavor.

In view of this situation, as long as the proportion of cooking powder is properly enlarged, it can be very close. In general, it is recommended to use 1:15 or 1:16 powder-water ratio in Qianjie.

The concentration of ② is low and the extraction rate is insufficient.

There are many factors involved in this situation. First of all, you should check whether the water temperature you use, the degree of coffee grinding and the ratio of powder to water are reasonable. For example, too low water temperature, too coarse grinding and so on will make a cup of coffee tasteless or irritating acid (low water temperature will make the extraction efficiency inefficient, too coarse coffee powder will lead to short contact time between water and coffee powder).

The second is to observe the state of the filter cup powder layer to see if a channel is formed, that is, water injection breaks through the coffee powder wall or over the coffee powder layer, resulting in the flow of water from the edge of the filter cup, resulting in insufficient extraction.

Last

Finally, the development of coffee is a dynamic process, during which new ideas will replace the old ones. In the case of defining whether the extraction is insufficient, the data of 18% cannot be used as the only indicator. We use the knowledge of the golden cup as the basis for brewing coffee, and the most important thing is to make a good cup of coffee. nowadays, some brewing schools use only the front and middle flavor substances of the coffee to be extracted and diluted to the appropriate concentration by adding water. In this method, the conversion extraction rate is less than 18%, but it is not the flavor shown by the insufficient extraction of one cup.

Therefore, Qianjie believes that the word insufficient extraction will put more emphasis on describing the phenomenon of acidity, saltiness, lack of aftertaste and so on.