Roasting of coffee beans | what are the roasting defects in coffee | which belong to baking defects

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Some of the defects in coffee flavor come from the defects of raw beans, some are caused by baking, and some are caused by brewing. Today, Qianjie Coffee will first talk to you about what defects will occur in roasting.

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.

Baking Baking

* Baking this baking defect looks no different from normal baking and can only be distinguished by "drinking"!

Coffee beans absorb very little heat in the roaster, absorbing less heat, and the total baking time is prolonged. The aroma of coffee beans is characterized by fast volatilization, long baking time and natural loss of aroma. The coffee baked in this way has a weak aroma, with the smell of grain and toast.

You can imagine what a bread will taste like if it is baked over low heat for a long time in the oven.

Cracked bean Chipping

In the process of coffee roasting, there are two bursting processes. The first burst is that there is water in the raw coffee bean fiber, and the water cannot come out. The pressure is caused by heating. When the coffee bean cell wall can not withstand this pressure, the coffee bean will crackle and burst. The second explosion is because the coffee bean itself is a wood fiber mechanism, and the coffee bean produces the physical phenomenon of pyrolysis due to combustion and heating, which makes the sound of wood structure rupture. "have a bang..."

* Coffee beans burst the cell wall for the first time by pressure

Okay, back to the point, what we call cracked beans is the coffee beans produced when the second explosion occurs. Why does the surface of the coffee beans crack? The reason is that coffee beans absorb less heat during the first explosion, and the expansion rate is not enough, resulting in more heat absorption on the surface, less heat absorption in the interior, and great difference between internal and external softness and hardness when the second explosion occurs. When the second explosion occurs, the surface with low density falls off. (dense coffee beans are also prone to this defect.)

* the second bursting of the wood structure of coffee beans

Top scorched TIPPING

This roasting defect is actually good and bad. Coffee beans have the lowest density at both ends, and the lowest density absorbs more calories. If it is shallow roasting, more heat absorption at both ends may bring sweetness, but if it is deep roasting, both ends absorb too much heat. It is easy to produce carbonized flavor and smoke smell when extracting coffee.

Locally charred Scorching

Before talking about this roasting defect, we first understand the three heat sources of the coffee roaster, namely, heat convection, heat conduction and heat radiation. The machine with more heat convection is not prone to local scorch, because the coating of hot air is good, and the heat absorption of beans is more "comprehensive". Then the roasting defect of local coke is easy to occur in the machine with more heat conduction and heat radiation, because these two heat sources have fast heat conduction velocity and low conduction efficiency. So it is easy to cause a "point" to absorb too much heat.

In modern roasters, most of them are machines with a lot of hot air, so this defect is not easy to occur. Generally speaking, this kind of defect is easy to occur in the roaster with more hand net baking and heat conduction.

Fast baking underdevelopment

* Fast baking (underdeveloped) is not much different from normal baking with the naked eye, and has nothing to do with the degree of baking. Don't think that shallow baking is fast baking. Fast baking actually means that the total baking time is too short (here, excluding the variables of different brands of baking machines, discuss under the premise of normal baking)

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