The principle and category division of coffee roaster Coffee Roaster

1. Commercial baking machine

The manufacturing principle of commercial baking machine is mainly divided into three categories: direct fire type, semi-hot type and hot air type. At present, the latter two roasts have the best effect and are the mainstream in the specialty coffee market.

1. Direct fire type

The earliest baking tools used by human beings are direct fire, that is, the hot roller is baked with fire, and then heat is transferred to the raw beans in the barrel. Although the motor keeps rotating the drum, stirring the coffee beans in the drum in an attempt to make each coffee bean evenly touch the hot iron wall to achieve the goal of balanced roasting. However, this baking method still has many shortcomings: iron heat conduction speed is not fast, it must take more time to complete the baking; fire outside the drum, hot air is dissipated in the air, failed to make good use of, it is a pity; when the raw beans touch the inner wall of the drum for too long, it is easy to be burnt, causing bitter taste and burnt taste; during baking, there are many fragments, which are easy to adhere to the surface of coffee beans in the barrel, which will make the flavor chaotic.

2. Semi-hot air direct fire type

Between 1870 and 1920, the German van Guben improved and manufactured the barrel baking machine. In his theory of roasting, he refers to coffee beans that bring hot air into roasting. In 1907, the German-made Perfekt roaster began to introduce this concept, using gas heating, with an air pump that carried half of the hot air into the drum and half to the outer barbecue drum. To this day, Germany's roller baking is still widely used, and the country's Probat roller baking machine is famous all over the world.

General roasters use gas or electricity as heat sources. Derrick Corporation of Idaho pioneered the use of gas-activated infrared heat sources in 1987 to achieve more accurate temperature control and was praised as the first brand in North America.

Today's roller baking machine is almost all semi-hot air direct fire type, one side to the fire directly to heat the roller, one side will be hot air into the roller. The hot air blown into the drum increases the heating speed and blows away the crumbs, thus producing balanced and clean coffee beans.

3. Hot air type

In the 20th century, some people thought of roasting coffee beans with hot air, so that there is less iron barrier, and the heat source can be transmitted directly to the raw beans to improve the roasting efficiency. In 1934, the United States by the Bern Company manufactured Thermo (jabez burns thermalo), that is, a large hot-air model, to this day, there are some large baking plants in the United States are still using the company's baking machine.

4. Airbed baking machine

The hot air roaster still uses the roller design, by rolling and turning the raw beans, to achieve the goal of balanced baking. However, someone thought of blowing the raw beans with hot air to make them float up and down, breaking the concept of the roller. In 1976, American Michael Schweiz designed the air bed baking machine. He blows hot air from below into an airtight container, causing the beans to float up and down the container until they are baked, then pour them out of the cooling tray outside the container and cool them. In Australia, renowned coffee expert Ion Berstein has similar designs and manufacturing.

During the normal baking process, less and less water evaporates from the beans and they become lighter and lighter. If you use this roaster, the heavy quality will fall faster, and then accept the roasting of hot air, so repeatedly up and down, that is, you can roast uniform coffee beans. However, the lack of metal roller burning, some people will feel that there is a lack of flavor.

Second, household baking machine

In recent years, there has been an upsurge in roasting coffee beans in small quantities. Many home roasting machines have appeared on the market, and roasting coffee beans by themselves has become quite simple. At present, household roasters can be roughly divided into three categories: self-fired, hot air and roller. Although these are not very sophisticated professional models, as long as they are properly operated, the roasted coffee beans are still fragrant.

1. Direct fire type: ceramic roaster or pan

The straight-fire type is the simplest, and can be a pan or a long-handled ceramic roaster made in Japan. The ceramic roaster is enclosed and has a stewing effect. It can roast delicious and complex coffee; it tastes the most natural and thick. Today, this ceramic roaster is often available outside Japan. The pan works poorly and is therefore not recommended.

The ceramic roaster is a simple way to bake. First, put the raw beans into a pot, and then shake them constantly on a gas stove with a long handle. The baker can control the amount of fire and control the baking time.

The disadvantage of this tool is that there is no hot air to blow off the silver film and debris, which is easier to have a miscellaneous smell; in addition, it does not have a cooling function. After baking, you have to pour the beans into the basket and use a fan or electric fan to cool them, which is more troublesome.

2. Hot air type: hot air popcorn machine or hot air household baking machine

The hot air popcorn machine was originally used for popcorn, and then someone used to roast coffee beans, and the effect was still good, once popular. Its shortcomings are: no function of collecting debris, hot air blowing debris film flying everywhere, after the effort to clean up; and heating speed is too fast, about 4-5 minutes can hear the first burst sound, moisture is not completely evaporated, taste is not full enough, slightly sour. The popcorn maker can bake 100 grams of raw beans at a time, less or too much to bake. It has no automatic shutdown function, so you have to look after it when you use it, otherwise you may burn the whole pot of beans.

These machines can be bought in specialty coffee shops or on websites in areas where coffee is popular. When using, just put in raw beans, set the baking degree, press the start button, from baking to cooling are automatically completed.

All hot air home roasters have crumbs collection and cooling functions to produce clean baked beans. The ideal baking degree setting should be able to judge the temperature and then automatically stop baking. However, the baking degree setting function of these machines is only a timer. When the time is up, it automatically switches to the cooling stage. Because winter and summer temperatures vary greatly, and the time required to roast coffee varies, the roasting scale may differ by more than a quarter.

3. Roller type household baking machine

Traditional baking machines are drum type, by the fire baking non-stop rotation of the drum. This roasting method has the characteristics of stewing, which will make the coffee beans older and taste fuller, similar to the effect of clay pot. At present, the AIpenrost model manufactured by Swissmar Company is available on the market, which belongs to the household roller baking machine. It can roast half a pound of coffee beans at a time, and the roasting time (including cooling and beans) takes about 21-25 minutes. The deeper the roasting degree, the longer it takes.

When using, just put in raw beans, set the baking degree, press the start button, from baking to cooling are automatically completed. The recommended baking degree of the machine is based on half a pound of raw beans. If the baking amount is less than half a pound, the actual time required for baking is relatively short. At this time, human intervention is required. When the desired baking degree is reached, press the "cooling" button, otherwise a pot of beans will be burned; if the baking amount exceeds half a pound, it may occur. In addition, it warms slowly, about 13-15 minutes to hear the first crack, so there is enough time to evaporate water, and then enter the high temperature cracking stage, so that the inside and outside of the coffee beans can be cooked, forming a richer texture. Therefore, most roasters think it is closer to commercial professional roasters, so Alpenrost has a good market in North America.

The baking degree setting function of this machine is just a timer, and when the time is up, it will automatically switch to the cooling stage. Because winter and summer temperatures vary greatly, the time required to roast coffee varies, and there may be more than a division difference in setting the roasting scale.

In winter, the rate of heating is too slow, and the machine cannot bring half a pound of raw beans to the roast of Espresso. Therefore, if you want to have heavy roasted coffee beans, you should reduce them moderately. In addition, its debris collection function is only a small plate at the bottom, so that debris and silver film automatically fall into the plate, and there is no hot air blowing debris, therefore, a lot of baked beans debris, it is recommended to use iron mesh to screen debris, otherwise it will produce more miscellaneous smell; secondly, there are more dead corners inside, the smoke of the stew is easy to leave oil, and the cleaning work afterwards is very time-consuming.