Coffee roasting machine to better roast coffee beans roasting temperature and time with roasting machine

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If the coffee roaster knows the structure of the roaster he uses, he can effectively control the whole roasting process. Coffee roasting is a process in which raw beans (Green Bean) are transformed into the flavor of ripe beans (Roast Bean) by heat generation of Non-Enzymatic Browning.

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Heat is a kind of physical energy that is measurable and proportional to temperature. The heat in the roasting process plays a leading role in the change of coffee flavor, so it can be said that understanding heat is tantamount to understanding baking. However, heat is difficult to quantify, and it is impossible to use exactly the same amount of heat for each baking. Therefore, it is important for bakers to understand the types, functions and differences of heat in order to maintain a complementary relationship.

The types and understanding of Heat

The heat used in baking can be divided into convection (convection), conduction (conduction) and radiation (radiant). Each roaster uses a different ratio. In the case of a general drum roaster (Solid Drum), the drum is heated by a combustion furnace, and the raw beans in the drum are absorbed by convection and conduction.

For example, Probat's Type-1 uses conduction 2: convection 8, but the new Type-2 uses almost 100% convection.

The W6 model of Giesen uses conduction 4: convection 6, while the W15 model uses conduction 1: convection 9.

2 ▲ Probat,Giesen

Conduction is the transfer of heat from the higher temperature part of the object to the lower temperature part of the object, and the heat transfer rate to the raw bean is slow. After the beginning of baking, the conduction accounts for a large proportion in the endothermic process of raw beans. However, overheating of the drum can lead to Scorching.

Convection is a process in which heat transfer is realized by the macroscopic flow of gases or liquids. Convection is better and more uniform than heat conduction. The proportion of heat transfer to raw beans is the most in the whole baking process. However, poor exhaust balance can lead to baking time being too fast or too slow.

Radiation (radiant) is emitted in the form of electromagnetic waves and particles, and heat transfer can be carried out without a medium. The external and internal heat transfer of raw beans is uniform, but it is difficult to control and accounts for a small proportion in actual baking.

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Types of ▲ heat

Types and characteristics of combustion furnace (Lamp)

The combustion furnace of the roaster can be divided into two furnaces, environmental furnace (Environment-Lamp) and infrared furnace (Infrared-Lamp).

The flame of the environmental furnace (or gas furnace) is blue and the height is low. It is used by most commercial roasters. The taste is characterized by good sour taste and heavy feeling (Body).

The flame of the infrared furnace is red and has no height. The representative roaster using this furnace is Diedrich of the United States. The taste is characterized by a balance between sour and sweet taste.

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Infrared furnace, gas furnace

Drum (Drum) and heating method

The structure of drum roaster (Solid Drum) is that there is a combustion furnace under the drum. Therefore, single-layer drum (Single Drum), it is easy to produce scorch (Scorching) phenomenon. In order to avoid this problem, some roasters install a heat dissipation plate between the combustion furnace and the drum, but this can not control the heat of the heat dissipation board, and it is not easy for the baker to control the roaster.

The double-layer drum (Double Drum) is made of two steel plates, and some of the outer and inner plates are made of different materials. Because of the double-layer plate, the conduction heat is lower and the chance of scorching is also low. Therefore, the baking result of double-layer drum is more uniform and stable than that of single-layer drum.

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Double drum, single drum

The roaster with 100% convection (hot air type) will not directly heat the drum, so coke burning will hardly occur. The baking curve of this roaster is HTST (High Temperature Short Time), the baking time is high, and the production efficiency is high. The representative roaster in this way is the Loring of the United States. The taste is characterized by high sour taste and low Body.

Thus it can be seen that the heat transfer ratio and mode of each roaster is different, and the coffee roaster should know the structure and characteristics of the roaster to apply it. The more the roaster knows the details, the more finished the coffee will be.

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