How do you drink the coffee powder? The principle and function of hand stew?

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About coffee steaming. Many baristas or enthusiasts have different opinions on the way, time and amount of steaming. They learn the process of steaming coffee from the physical principles of steaming coffee. When coffee beans are ground into coffee powder particles, the coffee powder particles we see with the naked eye are a whole particle, but in fact, the microscopic structure of coffee powder is actually a honeycomb-like structure with numerous through-holes. Freshly roasted coffee beans emit carbon dioxide continuously, and many of these carbon dioxide will remain in these through holes in the coffee beans at the beginning.

Imagine that hot water is poured directly on such a coffee powder in large quantities and at high speed, and the hot water will be extracted from the periphery of the coffee powder, and the internal carbon dioxide will be blocked by water and cannot be eliminated. Because there is carbon dioxide in the powder, hot water cannot penetrate into the coffee powder. Therefore, hot water will only constantly wash the surface of coffee powder, resulting in excessive extraction of the surface of coffee powder, but the interior is not extracted.

Therefore, the purpose of steaming coffee is to help coffee powder to expel carbon dioxide smoothly. In order to achieve this goal, the amount of water required must be appropriate, and gently let the water stop on the coffee powder, let it squeeze into the coffee powder a little bit, forcing the carbon dioxide to be discharged, so as to ensure the smooth extraction later. For hand flushing with this method of production, the amount of steam is the best to master. Steam just enough water to wet the powder layer, see the lower edge of the powder layer began to drip until. However, at this point, there are very high requirements for the way of water injection, which requires that the water injection must be gentle, stable and fast, and it is best not to bubble on the surface of the steamed powder layer. Because if foaming, it means that the local water injection is high, resulting in water flow directly through the powder layer, and the powder particles are not evenly soaked.

At this point, the coffee powder layer has been fully saturated, and water begins to penetrate into the coffee powder to squeeze out the carbon dioxide. We can clearly see that the powder layer begins to swell, and the carbon dioxide in it is continuously discharged, but if the best time to re-inject water is when the carbon dioxide is completely discharged and the coffee powder layer begins to collapse. However, it really needs to be observed very carefully when it collapses, but if it cannot be observed for the time being, we suggest that the newer the coffee beans, the longer the steaming time. For example, the stewing time of freshly roasted overnight can even be reduced to 45-50sec, the coffee beans after three days can be appropriately reduced to 30-35sec, and the stewing time of coffee beans after one week can only be reduced to about 20sec. If the coffee beans with a long time can not swell after water injection, it is recommended to cancel the steaming and direct secondary water injection.

Similarly, for the French press pot, electric drip filter, Philharmonic pressure and other appliances, we also hope that everyone has achieved more efficient extraction for the relatively new coffee beans by adding the steaming process. The amount of steaming water and time can be appropriately referred to the hand flushing, but the amount of steaming water for the French pressure is recommended to be appropriately reduced.