Coffee common sense the judging method of Italian coffee oil is determined by the flow rate.

The flow rate of Italian coffee directly determines the taste of ESPRESSO, too fast flow rate will make the essence of coffee has not been dissolved into the water, but the water has passed through the coffee powder, resulting in coffee tasteless; too slow flow rate will make the essence and dross of coffee all into the water, resulting in coffee with obvious scorching taste or exciting bitter taste. For beginners, the flow rate control is a quantitative standard, generally we take 22 seconds to 28 seconds as the best value. The more advanced ones will judge the flow rate by the shape of the water flow when the coffee is extracted. Foreign baristas like to use the mouse tail to describe the flow rate of coffee. The higher level is that the flow rate of coffee is determined by its taste. If the flow rate is faster, the taste will be single but refreshing, and the sour taste will be heavier; if the flow rate is slow, it will increase the mellowness, and the more complex but bad taste will be released at the same time. The bitterness will be a little heavier. The speed of the flow rate is a dynamic process, no barista or any kind of coffee equipment can guarantee the consistency of the coffee flow rate, and even the humidity of the weather will affect the speed of the coffee flow. So baristas must know that it is easy to control the flow rate rather than being controlled by it.