Drinking coffee must start with raw coffee beans.

The Espresso boiled at the ideal water temperature is very dark reddish brown, and the foam on the outside will be mottled with dark brown (the Italians call it "el tigre"), and the foam should be more than 4mm thick.

On the whole, large coffee beans produce better coffee. In the case that the quality of coffee beans is now fully mastered, the first skill problem to be dealt with is "blending". "blending" refers to the selection of coffee beans of different origin and quality to achieve the desired results. The "matching skills school" trust: 50% of the success factors of a perfect Espresso depend on the composition and quality of the match. No single-origin coffee can fully fulfill the taste required by Espresso. Coffee beans from African and Arab coffee trees are characterized by clutter, large berries and floating aromas, while coffee from Latin America is clean, full-bodied and refreshing, while coffee from Southeast Asia is characterized by satisfactory fruit and earthy smell. Many coffees are a mixture of several types of coffee, making the taste more messy.

A perfect match is not a random mix of several boutique coffee beans. The basic blending process is to first decide the benchmark beans, then participate in the coffee beans that can increase flavor and special flavor, and then change the blending coffee according to the mixing share and roasting degree of all kinds of beans. Raw beans for blending have their own characteristics to prevent the flavor from being similar. The quantity and share of blended coffee beans depend on constant testing, so before blending, they mostly choose the method of mathematical combination to draw up a matching schedule, and then determine the best plan through the process of assembling cups.

Bake first and then match, or match first and then bake? This has always been a controversial topic between bakers and assemblers. As if blending wine is the same, blending before baking can make the aroma and quality more uniform, but the "decay" of roasting must be taken into account, as coffee from different places requires different baking time and temperature. If you have a determined formula, you can put different coffee beans together and then bake them together. Most long-established coffee makers have their own secret recipes.

In contrast to the "matching skills group", the "baking skills group" believes that 80% of the taste of coffee depends on baking. Regardless of the percentage of negligence data, whether the degree of "baking" is exquisite or not, and whether it is self-baking or not, this has indeed become the primary goal of verifying the identity of a coffee glutton. "roasting" refers to roasting raw coffee beans with a special machine, so that the coffee beans show a common coffee color, aroma and taste, the key is to evenly "stir-fry" the inside and outside of the beans without being overburnt. A series of chemical changes occur during the baking process: moisture decreases from 10% to 1%, fat from 12% to 16%, sugar from 10% to 2%, chlorogenic acid from 7% to 4% to 5%, and nitride from 12% to 14%. The physical change is that water is lost, the weight is reduced by 10% to 15%, and the volume is increased by 60%.

A vivid analogy is: "the roaster is a machine between a popcorn machine and a clothes dryer." The temperature in a large industrial baking bucket can reach 288 degrees Celsius, coffee beans turn yellow first, and popcorn tastes like popcorn. About 8 minutes later it began to snap and expand, and when the temperature reached 204 degrees Celsius, the coffee beans began to turn brown and the oil began to spill. The spilled oil is called "caffeine" or "caffeine", and the chemical reaction between calories and caffeine is called "pyrolysis", which produces a strong coffee flavor in this process. In another 3 to 5 minutes, the machine will announce the sound of snapping again, and the color of the coffee will soon change to a dark color, indicating that the baking is now over. When the preset baking temperature is reached, the baking can be stopped with cold air. The roasted coffee beans are wrinkle-free, glossy and symmetrical, fully demonstrating their unique flavor. If the early stage of baking is too irritable, the bean skin will be mottled and the taste will become bitter and choking.

Generally, roasting is divided into three degrees: shallow, medium and deep, and the length of baking time varies according to the type of coffee required. The slightly roasted coffee bean color is light and sour, the intermediate baking is sour and bitter, and the deep roasting color is rich and bitter. The lighter the roasting degree is, the stronger the sour taste of the coffee bean is, the deeper the baking degree is, the sour taste is gradually lost, and the bitterness is heavier. Professional baking methods are generally divided into the following eight stages: very shallow baking (Light Roast), shallow baking (Cinnamon Roast), micro baking (Medium Roast), medium baking (High Roast), medium and deep baking (CictyRoast), deep baking (Full-City Roast), very deep baking (French Roast) and very deep baking (Italian Roast). Deep baking, also known as "Italian baking", is mainly popular in Latin countries and is considered to be the most suitable for Espresso. The color of the very deep-roasted coffee beans is black and the oil is now soaked to the outside so it has a bitter taste of carbon ash and its mellowness is significantly reduced.