Types of Coffee Roasting Machines

Types of Coffee Roasting Machines

Whether you are starting a coffee roasting business or you would like to start roasting from home as coffee lover, the high price tag of a coffee roasting machine means you want to get your purchase right from the start. This guide will go over the different types of coffee roasting machines out there and which heating methods they utilize to help you choose the best roaster for your business.

There are three types of coffee roasters in the market: direct fire coffee roasters, semi fired semi-hot air coffee roasters and hot air coffee roasters.

1. Direct Fire Coffee Roasters

The biggest feature is that the surface of the drum has a perforated design, the holes have a certain size and interval, and the fire can be directly burned to the bean surface. Although the coffee beans can be heated evenly by turning the drum, but if the fire is not well controlled, it would still be easy to over-roast the surface of the beans, causing the situation that the outside is cooked and the inside is not cooked. The direct fire type uses the exhaust valve to adjust the heat. This will test the roaster's skills.

• Advantages: short preheating time. compared with hot air and semi-fire semi-hot air roasters, the furnace wall of direct fire type roasters is thinner, so the overall average preheating time of the drum is shorter.

• Disadvantages: the heat in the drum is not easy to adjust, because the drum has a hole design as a whole. When the furnace fire provides the first vitality at the bottom of the furnace, the heat energy will be emitted from other holes immediately, resulting in insufficient heat. However, if the temperature is increased in order to supplement the heating power, when the profit exceeds the acceptable level of the raw beans, it will be burnt. Therefore, it is necessary to carefully look at the amount of raw beans to adjust the heat from time to time.

2. Semi-fire Semi-hot Air Coffee Roasters

Also known as “Drum Coffee Roasters”. It’s the most popular and economical type of roasters. The roasting method is combining the advantages of Direct Fire Coffee Roasters and Hot Air Coffee Roasters. This roaster machine features a solid drum that rotates over a gas flame/electric heating elements to heat the coffee beans. The beans receive both conductive heat transfer by making direct contact with the surface of the drum and convection heat transfer from the ambient air inside the drum. There are paddles inside the drum to mix the beans as the drum rotates and ensure they receive the right blend of conductive and convective heat. 

With the exhaust device added to the machine, the hot air outside the drum will be introduced into the drum to improve the roasting efficiency. Another function of this exhaust device is to suck the silver skin off the coffee beans to avoid the silver skin burning in the drum due to high temperature and affecting the taste of coffee beans. This type of roasting machine has the advantages of both Hot Air Coffee Roasters and Direct Fire Coffee Roasters, and the heating method is changed by adjusting the hot air and the speed of the drum. The more the hot air is turned on, the faster the speed is, the closer to the hot air type, otherwise it is close to the direct fire type.

Advantage:

• Gives the beans a deep, full-bodied flavor
• Applies both conductive and convective heat sources to roast beans
• Flexibility in control
• Available in single-wall and double-wall styles for preference
• Comes in a variety of sizes
• Ideal for high-volume roasting

What Is Conductive Heat?

Conductive heat occurs when heat transfers between two objects in contact with each other. When roasting coffee, this refers to when the beans come into contact with the hot metal surface of a drum roaster. Conductive heat transfer is a more traditional style of roasting that roasts the beans from the outside in, similar to cooking meat in a frying pan.

What Is Convective Heat?

Convective heat is the transfer of heat through a liquid or gas. When roasting coffee, this refers to when heat is applied indirectly to the beans via hot air. Coffee roasters use a fan or pump to pull air into the roaster and heat the beans. Convective heat transfer is a more modern and upcoming style of roasting that roasts the inside out, similar to baking.

DY, BY, BR, YS and SD series supplied in our store are semi-fire semi-hot air coffee roasters, covering wide range of capacity for your option.

3. Hot Air Coffee Roasters

Also known as “Fluid Bed Coffee Roaster”. A Hot Air Coffee Roaster relies solely on convection heat transfer to roast coffee beans. It consists of a tall cylinder where hot air rises through a chamber into the roaster and causes the coffee beans to float in a fluidized bed of hot air to roast them. A Hot Air Coffee Roaster is typically electric, which can be great for companies trying to reduce their carbon footprint.

Compared to Semi-fire Semi-hot Air Coffee Roasters, Hot Air Coffee Roasters are known for roasting coffee beans more evenly and in a quicker amount of time as the air has complete and constant contact with them. However it will take longer to to preheat for first batch of roasting. These roasters eliminate the risk of scorching associated with conductive heat since the beans do not come in direct contact with the roaster. They are usually compact machines, making them ideal for small-batch roasting.

Advantages:

• Roasts coffee faster and with less energy than drum roasters
• Provides more even heat distribution and a more consistent roast
• Less likely to scorch beans
• Compact size is ideal for small roasteries

We supply 150g, 300g small capacity Hot Air Coffee Roasters for home and sample roasting.