How many grams of powder and liquid do you need to extract espresso? Can I make espresso twice?

As we all know, we usually extract espresso according to a certain formula. For example, the formula used in Qianjie is a powder-to-liquid ratio of 1:2, and the extraction time is controlled at about 30 seconds. The purpose is to get an espresso with an extraction rate and concentration that meet or are close to our standards.

But occasionally, we will be distracted for some reason, and the extracted espresso does not reach the target liquid weight. For example, we were supposed to extract 40ml of coffee liquor, but the extraction was stopped when 28ml of coffee liquor were extracted. Obviously, this cup of espresso is far from the liquid weight of our goal, so there is a high probability that its taste will not be any better. So at times like this, I believe many friends on Qianjie will think: Can we press the extract button again to "replenish" the amount that is not extracted enough? At least Qianjie had this idea when he first started. So today, Qianjie plans to share with you through experiments whether such an idea is feasible. The content of the experiment is also very simple, which is to extract a normal concentration first, and then extract multiple "re-extracted" concentrations for comparison to see if there is a difference between the two. If so, then how big will the difference be?

Experimental sharing The coffee beans used in Qianjie in this experiment are Qianjie Strawberry Candy·Espresso in Qianjie bean list. This is a special blend of Qianjie in order to make the extracted espresso coffee also have a strong aroma of flowers and fruits. Coffee beans. Because Qianjie is made from Costa Rican and Ethiopian coffee beans with strong fruit and fruit aroma and mellow Colombia coffee beans, the coffee made with this blended beans will have strong white flowers, strawberry fudge, citrus, cream and other amazing flavors. At the same time, it will also have a soft and mellow taste, and the taste will not be very sour and is relatively balanced. Made into American, latte and other coffees will have excellent flavor and rich layers. It can be said that it is a hexagonal warrior very suitable for producing Italian coffee.

As Qianjie mentioned earlier, Qianjie uses the extraction parameters used to make espresso coffee: a powder-to-liquid ratio of 1:2, a time of about 30 seconds, and a powder amount of 20g, which means that 40ml of coffee liquor should be extracted. In addition to the concentration for conventional extraction, Qianjie will extract three more cups of concentration, which will stop the extraction when one-half (20ml), two-thirds (26ml), and fifths of the target liquid weight.(32ml), and then restart the extraction until the liquid weight reaches the target. We skipped the extraction process and now we have four espresso shots. From left to right, they are: "one-half concentrate","two-thirds concentrate","four-fifths concentrate", and espresso coffee with normal extraction.

Measured by a concentration meter, their final concentrations were 10.17%, 10.35%, 10.47%, and 10.53%. It can be seen that the difference in coffee concentration is still quite large, especially the earlier the extraction time, the greater the gap between the coffee concentration and the normal extraction concentration. Although they all taste delicious, the difference is also very obvious. The concentrated extract at one-half of the weight of the target liquid will taste relatively thinner, while the coffee will become stronger as it goes later, especially the normally extracted coffee, which has outstanding sweetness and full taste, strawberry and floral flavor. The flavor is very obvious and super delicious.

The reason why there is such a difference is that the extraction efficiency of stopping the extraction and then resuming the extraction will not be as high as before, and this has to mention the unique extraction method of the coffee machine-pressure extraction. Pressurized extraction uses pressure to assist hot water extraction of coffee. Unlike normal pressure extraction, this method has extremely high extraction efficiency and will allow a large amount of flavor substances in the coffee to dissolve out in a short period of time.

But the condition for the coffee machine to apply pressure is that the powder must have enough resistance. The higher the resistance of the powder, the greater the pressure will be applied by the coffee machine. So we use a very, very fine grind to grind coffee beans, in order to prevent hot water from passing through easily and force the coffee machine to apply greater pressure for extraction. What everyone needs to know is that even if the powder we used at the beginning had extremely high resistance, as soon as the extraction started and the coffee machine started applying pressure, the resistance of the powder would gradually decrease. Although there will still be escaping carbon dioxide to slow down the water launch rate at first, as carbon dioxide decreases, the flowing channel of hot water gradually increases, which is why the flow rate gradually increases as the extraction process progresses.

If we stop the extraction halfway, the coffee machine cannot apply the same pressure to extract the coffee when we start the extraction again. The reason is simple. The density of the powder cake has been changed during the previous extraction process, and then there is not much carbon dioxide that can hinder the penetration of hot water, so even without pressure assistance, hot water can easily pass through the powder layer. Compared with the original, the extraction efficiency will be much lower. Originally, it took 10 seconds to complete 20ml of espresso liquor after Qianjie extraction. However, after re-extraction after the extraction was interrupted, it took less than 5 seconds to extract all 20ml of coffee liquor. Therefore, the extraction rate of coffee will be lower than before. The earlier the extraction time node is stopped, the more the difference will be in the extraction rate, which will affect the taste, concentration, and taste of the coffee.

To sum up, you can know that if you break the extraction early, then it is best to re-grind a portion of coffee powder and start the extraction again to avoid the quality of the coffee produced far deviating from your standards. But if the node that is cut off is relatively late and almost all of the extraction is completed, then whether the remaining amount needs to be made up depends on the individual ~

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FrontStreet Coffee is a long-established specialty coffee roaster in Guangzhou China, selling freshly roasted beans from its own farm in Yunnan as well as dozens of carefully selected single-origin beans from around the world for both pour-over and espresso. The products deliver consistently excellent quality and great value, with shipping within 24 hours. Guangzhou’s FrontStreet Coffee shop is recommended by many coffee lovers, and the beans are now available online at the Tmall 。

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