About extraction and powder quantity

According to the habit of many baristas, the amount of powder we set has far exceeded 14g (two portions). A friend asked me whether this is a problem of excessive extraction, or whether the current standard needs to be changed.

At this point, there is a tidbit that in 2003, Australian barista Paul Basset won the WBC championship (Australia's only WBC championship.) The runner-up at the time, Tim Wendelboe, the 2004 champion, raised questions after the game. Because Paul is tapping while receiving powder, his powder quantity is much higher than that of other contestants. Although we can see that this practice is not unusual now, at that time, we began to have a different view of Dr. illy's 14g.

I am very concerned about these four words, excessive extraction. Because we sometimes unconsciously mix high concentrations with excessive extraction. High concentration means that the soluble substance in coffee is on the high side. Using the standard of espresso, which is higher than 11%, we can call it high concentration. If you use the standards of the American Fine Coffee Association, filtered coffee is about 1.5%. However, when we mention excessive extraction, in fact, it is not directly related to the concentration in the liquid. More importantly, how much substance can be extracted from our coffee. And this range, whether it's espresso or filtered coffee, we basically set it between 18% and 21%. So what does that mean?

Extraction rate icon of filtered coffee (picture excerpt from SCAE Filter Coffee handout, not self-made)

The highest soluble substance in coffee is about 30%. When making coffee, if we are less than 18%, then coffee is not easy to be fully extracted. If it is higher than 21%, we may extract substances that we do not want. So, more strictly speaking, whether coffee is over-extracted has nothing to do with how much water we add, but how long we extract, how much coffee we have extracted during this period, and the temperature of our water. how much pressure makes us extract per unit of time.

Therefore, here is a conclusion that is actually completely contradictory to that friend. That is, if the other parameters remain the same, the increased amount of powder means that our extraction rate is reduced per unit time. To be more popular, only 14g of coffee was passed by water in 30 seconds, but now there is 20g, so compared with the total amount of 20g, the amount of substances and denominators we extract is lower than that of increasing the total amount of coffee powder.

Speaking of which, we can actually understand or understand some phenomena.

1. In the WBC competition, the balance and cleanliness of the taste is extremely important. So the cleanliness of the taste has a lot to do with preventing excessive extraction. With an increase in the amount of powder, it is helpful to extract as many substances as possible per unit time.

two。 This is not an axiom, but it is a universal experience. At the same flow rate, small powder / fine grinding tends to reflect the flavor than large powder / rough grinding, but at the cost of the loss of some alcohol (less powder). However, please note that in the early 14g, that is, in Italy, the degree of roasting tends to be deep-baked, and there will even be coffee beans with deep oil in the middle of the second explosion in southern Italy. In this case, the coffee beans are carbonized seriously, so they are too full and lose their flavor obviously. At that time, the amount of powder decreased, adjust fine grinding, as much as possible to extract some flavor is necessary. This is a bit like hand brewing. If the roasting degree of coffee is too high, we should actually reduce the amount of powder accordingly. However, today, the concept of boutique coffee comes out, and the coffee we drink is just the opposite. In order to highlight the flavor, the degree of roasting is greatly reduced. Then we need to increase the amount of powder to make up for the lack of alcohol.

3. We finally have to return to the most basic concept, the problem of extraction rate. In other words, whether 14g or 20g is reasonable depends on whether the extraction rate is in an acceptable range.

We all know that 25-30ml espresso is extracted in 20-30 seconds at 9 atmospheric pressures at a high temperature of about 93 °. And the extraction rate is 18-21% and the concentration is between 8% Mel 11%, we call it espresso.

Well, what we need to talk about today is the amount of powder. 9 atmospheric pressure, water temperature, extraction flow rate can be unchanged, because whether the extraction flow rate is 14g or 20g, it can be achieved by adjusting the grinding degree. What we are going to see today is whether there has ever been a question of excellence.

Remember the espresso I made from the Italian capsule last time? http://www.douban.com/note/192204273/ used fresh espresso, a serving of 7 grams, and made 18 grams of espresso with a concentration of 8.8 percent. The reason why I don't use volume is that the weight is more accurate. However, at that time, because of the rich oil, the cup of espresso had 25ml. And we got 1.584 of the soluble matter in 170.088g coffee powder, or 7g coffee powder. That is, exactly at the extraction rate of 21%. But we can see that if the concentration is higher, it will be higher than 21%, right on the edge of the extraction.

Using the example of seven seeds made a few days ago, my powder quantity is 19g (9.5 per serving), and the concentration is 10.9%, and the espresso I extracted is also about 28ml, and the weight is 17g. Then our extraction rate is 170.109, which is 9.5 or 19. 5%

Obviously, whether it is 14g or 20g, as long as it is extracted properly, a suitable espresso can be made. Then what needs more attention is the characteristics of coffee beans.