Coffee roasting | Maillard reaction

[definition of baking]

The so-called coffee roasting (coffee roasting) refers to the process that through heating the raw beans, a series of physical and chemical reactions take place inside and outside of the coffee beans, and in this process, the sour, bitter, sweet and other flavors of the coffee are formed, forming mellowness and hue, and transforming the raw beans into dark brown beans.

[Maillard reaction] what is it?

In fact, to put it simply, Maillard reaction is: protein + sugar, cooking at a high temperature above 150 degrees Celsius, the scorching phenomenon of food. Is it still not clear?

Maillard reaction

Maillard reaction is one of the most complex chemical reactions that take place during coffee roasting. After Maillard reaction, coffee beans will contain more than twice as much flavor as raw beans before baking. Therefore, Maillard reaction is one of the most important reactions to produce thousands of flavors of coffee.

Maillard reaction means that amino compounds (amino acids and proteins) and hydroxyl compounds (mainly glucose, fructose, lactose, maltose and other reducing sugars) undergo a series of complex reactions to form brown compounds and then form black macromolecular compounds-melanin-like compounds in the later stage of the reaction. So Maillard reaction is also called non-enzymatic browning reaction.

Maillard reaction process

During coffee roasting, the Maillard reaction mainly begins when the bean color changes to yellow and then brown after dehydration, and the reaction does not stop until the beans are completely cooled. But at the beginning of the explosion, another reaction that plays an important role in the flavor of coffee, the caramelization reaction, will begin, and it will share the same raw material-sugar as Maillard's reaction. The rate of Maillard's reaction began to slow down. Therefore, the main Maillard reaction stage refers to the period from the beginning of yellowing to the explosion of coffee beans in the roasting process. Melanin, a macromolecular compound, is continuously produced during the reaction, and more than 600 volatile organic compounds are eventually found in roasted coffee beans. So Maillard reaction brings flavor, taste, color and complexity to coffee.

Then, in the process of coffee roasting, we can adjust the degree of Maillard reaction indirectly by adjusting the rhythm of roasting, and then adjust the flavor of coffee.

Since the Maillard reaction has little effect on the reaction rate by increasing the temperature after 80 degrees Celsius, it is generally adjusted by prolonging or shortening the reaction time. Prolonging the Maillard reaction time will produce more macromolecular melanin, which will bring thicker taste, more complex and deeper flavor to the coffee.

On the contrary, shorter reaction time will result in lighter taste, lower complexity and brighter tonality. Too long reaction time may make the tone of the coffee too low, the sour texture heavier, dirty or the mouth feel "dry" after swallowing. Too short reaction time may make the coffee flavor too green and monotonous or even almost no flavor, similar to seed, immature fruit taste, sharp sour, too much astringency, no texture.

With the increase of reaction time, there is a fresh floral and fruity aroma to a lower tonal aroma of flowers and fruits, followed by more nuts, vanilla, cream and caramel, but the aroma of flowers and fruits will begin to weaken.

Cinnamon Roast:

Cinnamon baking: this is the lightest kind of baking. There is no oil on the surface of the coffee beans. Large coffee bean manufacturers often mix the lightly roasted coffee beans with the coffee beans they sell. Because it can save money and increase the quantity. Cinnamon-roasted coffee beans usually don't appear in.

City Roast:

Urban baking: the name of baking first appeared in the 19th century. It usually means "thick". But as time goes on, the color of roasted coffee beans gets darker and darker, so a new name becomes inevitable. Today, "City" roasting is only a little darker than "cinnamon roasting". People use "Full City" to call moderately roasted coffee, which is slightly darker than "cinnamon roasting" in color. There is no fat on the surface of the coffee beans.

Vienna Roast:

Viennese roasting: this is the next level of baking. Traditionally, Vienna Roast is a mixture of coffee beans from different baking times. But in fact, during this baking period, the oil inside the coffee bean has just appeared on the surface, with dark brown spots on the surface. This is a moderate baking phenomenon.

Italian Roast:

Italian BBQ: this is the next level. At this time, the surface of coffee beans is covered with more than half of the grease. The color of coffee beans is the brown of cream chocolate. Italian copying varies from place to place in terms of choice and color.

French Roast:

French roasting: coffee beans that Europeans like to use are usually roasted until the surface of the beans is covered with oil and the color is like bitter chocolate. at this stage, the coffee beans have been severely carbonized, and it is difficult to distinguish the taste of one kind of coffee bean from another. This is a strong flavor.

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