coffee roaster

Coffee roasters are classified into three main types according to the heating method: direct-fire, semi-direct-fire and hot-air.

Direct-fire roaster: This roaster uses flame to transfer heat directly to the coffee beans, and the boiler surface has a perforated design so that the flame can burn directly to the bean surface. Although it is possible to make the coffee beans evenly heated by stirring the drum, it is difficult to control the fire, and it is easy to scorch the surface of the beans, resulting in the situation that the outside is cooked and the inside is not cooked. Direct-fire roasters regulate the heat through the exhaust valve, which is a great test of the roaster's skills.

Semi-direct-fire roaster: This roaster combines the characteristics of direct-fire and hot-air roasters. There are no small holes inside the drum, so the flame can't roast the beans, but instead transfers heat evenly through the metal of the drum. This way makes the beans roast more evenly and is the most widely used heat transfer method on the market today.

Hot air roaster: Using a blower to draw in air, the temperature of the air is raised by a heating coil, and the hot air is used as a heating source to roast the coffee beans. The hot air not only provides the temperature needed for roasting, but also uses the airflow to stir the coffee beans so that they are evenly heated. The advantage is that it heats up quickly and the raw beans are heated evenly. The disadvantage is that heating up too quickly can easily cause the beans to be trapped, and too high a temperature can easily make the caramelisation of the coffee insufficient.

These different types of roasters have their own advantages and disadvantages and are suitable for different roasting needs and flavour preferences. Choosing the right roaster takes into account the skill level of the roaster, the type of beans and the desired flavour of the coffee.