How do you make espresso grease?-how about Dongling espresso machine

How do you make espresso grease?-how about Dongling espresso machine

The color of the oil had better be golden yellow and slightly brown, and the color of the oil is milky white, which is generally called insufficient extraction, while the preference for dark brown is excessive extraction.

Insufficient extraction

The lack of extraction is generally reflected in the milky white color of the oil, which may be due to insufficient powder, too light filling force, too low water temperature, too coarse coffee powder, insufficient water pressure or not fresh coffee beans. sometimes it is also related to the light roasting of coffee beans or the variety of coffee beans.

Excessive extraction

Excessive extraction is generally reflected in the dark brown color of the oil, which may be caused by too much powder, too much filling force, too high water temperature, too fine grinding of coffee powder and other reasons, sometimes it has something to do with the excessive roasting of coffee beans. The grease color of espresso is the most basic knowledge that coffee lovers and baristas must understand and master, which can help you understand the quality of coffee in the shortest possible time.

Emulsification: the role of a liquid in which tiny droplets are uniformly dispersed in another liquid that is immiscible. Emulsification is a liquid-liquid interface phenomenon, in which two insoluble liquids, such as oil and water, are divided into two layers in the container, with low-density oil in the upper layer and high-density water in the lower layer. If the appropriate surfactant is added under strong stirring, the oil is dispersed in the water to form an emulsion, which is called emulsification.)

(phase state: that is, the state of matter (or phase for short, also called physical state), refers to a set of states of a macroscopic physical system. A substance in a state has simple chemical composition and physical properties (such as density, crystal structure, refractive index, etc.). The most common states of matter are solid, liquid and gaseous, commonly known as "three states of matter".)

What is crema? Why did crema disappear?

A series of complex chemical changes occur during coffee roasting to produce large amounts of carbon dioxide. Most of the carbon dioxide will be released naturally during the storage of ripe coffee beans, but more carbon dioxide will remain in the cell wall.

The pump pressure correlation of 9 bar is the insoluble oil in emulsified coffee. In fact, water pressure has another function, which is to make water supersaturated to carbon dioxide, increasing the solubility of water to carbon dioxide, thus dissolving more times more carbon dioxide than normal natural pressure. That's why hot water forms thousands of tiny bubbles when it passes through pressed powder.