Tea can be brewed back and forth, why can't coffee be brewed repeatedly?

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"the tea can be washed back, so why can't the coffee be brewed repeatedly? "

This is a question that the editor is often asked by guests. Do you have the same doubts? On this issue, we should start with the characteristics of coffee beans. Generally speaking, ripe coffee beans are composed of soluble aromatic substances (about 30%) and wood fibers (about 70%), but when brewing coffee, do not think that the more aromatic substances are extracted, the better the coffee tastes. The principle is actually the same as squeezing Sugar cane juice.

Sugarcane is composed of water, sugar, minerals, vitamins, amino acids and other nutrients and fiber. Whether it is juicing or chewing, what we eat is juice. But even if the machine squeezes juice, there is still a small amount of juice in the discarded fiber, that is, 100% of the juice cannot be squeezed dry. If you collect the discarded fibers and repeatedly squeeze the juice to drink, some of the fibers will enter your mouth with the juice, bringing a bad taste.

Just like sugar cane, if the coffee is brewed repeatedly, it will become bitter and bitter, so generally speaking, coffee with an extraction rate of 18% to 22% will taste better. The soluble aromatic substances in coffee adhere to the cell walls of ripe coffee beans, dissolve when in contact with water and are taken out with water, a process we call coffee extraction. The deeper the roasting, the looser the internal space of the coffee beans, and the easier it is to release the aromatic substances. After the ground coffee comes into contact with hot water, it only takes two or three minutes to bring out most of the delicious flavor.

When the water constantly washes away the coffee powder, the aromatic substances are constantly released. When about 22% of the aromatic substances are taken out, if you continue to inject water, the liquid will have a miscellaneous smell, just like repeatedly squeezing the fiber of sugarcane. The soluble substances of coffee contain aromatic substances with medium and low molecular weight, as well as insoluble substances with high molecular weight. According to the dissolving rate, acid and fruit aroma are first released, followed by sugar and caramelized flavor, and finally bitterness and impurities.

So when brewing coffee by hand or brewing earbags, don't think of more than one bag or one cup because of petty gain, because after the coffee is brewed normally, there are only bad impurities and wood fibers left!