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Why is Extraction Speed So Important for Optimal Coffee and Espresso Taste?

Coffee consists of 70% wood fibers that are insoluble in water. The remaining 30% is water soluble. During coffee extraction, water-soluble components (flavours, oils, bitter substances, acids and minerals) from ground coffee are dissolved with the help of water. Therefore, extraction describes the extraction of soluble fractions from a solid. If all 30% is removed, but only 18% - 22% is removed, you will not achieve the best flavor result in the cup. Then the balance between bitterness and acidity is best and you can taste a certain sweetness in natural unsweetened coffee/espresso. Thus, the balance between acidity and bitterness can be determined by the extraction rate,

Sample extraction rate: With an extraction rate of 20% and the amount of ground coffee used in 18 g, 3.6 g of substance (= 3.6 g of positive coffee aroma) is released from the coffee.

18% - 22% subtraction rate

In the 1960s, a study was commissioned by the Coffee Brewing Center in the USA to determine the coffee extraction preferences of filter coffee consumers. Data from the Coffee Brewing Center show ideal coffee extraction when 18% to 22% of ground coffee is dissolved in hot water. This specification of "correctly brewed" coffee has been adopted by various international coffee associations, including the Norwegian Coffee Association (NCA) founded in 1975, the Specialty Coffee Association of America (SCAA) founded in 1982, and the Specialty Coffee Association. Europe (SCA was founded 1998). Thus, the extraction rate between 18% and 22% has become the global standard.

Extraction rate is crucial for a balanced beverage

An espresso tastes best when the balance between bitterness and acidity is at its best. The balance between acidity and bitterness can be determined by the extraction rate, which can be measured using a refractometer. The extraction rate tells you how many ingredients are separated from the ground coffee during the brewing process. If it's below 18%, it's called incomplete subtraction in technical jargon. In this case, the coffee/espresso is acidic and the flavors are underdeveloped. Especially a lightly ground coffee/espresso is deficient in the body. If the extraction rate is more than 22%, it is called over-extraction. Filter coffee or espresso turns bitter, tastes unpleasantly intense and sometimes burnt. In this case, too much (unpleasant) content has been removed from the coffee bean.

Subtraction rate? Is it really that important?

If, at the start of your career as a home barista, the issue of extraction rate seems a little too big for you and you really don't want to deal with it, we get it - after all, it's all about brewing a drink. . However, it's really worth examining, because the extraction rate is what determines whether a coffee/espresso is a "scientific" success or failure. Therefore, if you are not sure whether your coffee / espresso is good or bad, we recommend purchasing the VST LAB coffee refractometer for baristas. Of course, you don't make such an investment every day. But with the help of a refractometer you gain absolute control. It also allows you to calibrate the various components in espresso preparation to suddenly be very close to your perfect coffee/espresso.

Guidelines for an ideal extraction even without a refractometer

If you don't have a VST LAB Coffee Refractometer, you can follow simple guidelines for brewing strength and extraction speed to get a compatible beverage. For this you need a digital scale with which you can determine the amount of ground coffee and the amount of water/filling.


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