The Distinction between Hot Air Roasting and Drum Roasting

Roasting Coffee Beans

Coffee roasting is a time-consuming procedure that includes carefully applying heat to green coffee beans to change the seed's essential components–sugars, proteins and acids–into exquisite fragrances of roasted nuts, malts, chocolate, fruit, berries, and flowers.

Each coffee is carefully selected, combining scientific data logging with intuition and expertise to obtain a balanced taste and optimal flavour. There are two primary techniques of roasting: conventional drum roasting and hot-air roasting. But first, let us discover what happens in the process of coffee roasting.

The Coffee Roasting Process

The green coffee beans are roasted for an average of 11 minutes, and their temperature is increased from 120 to 400 degrees Fahrenheit, causing the chemical reactions that affect flavour. The more the green coffee beans were roasted, the darker the beans became. The length of the roasting time depends on the roasting method.

Two Methods of Coffee Roasting

To better understand coffee roasting, let us differentiate the two methods of coffee roasting.

Traditional Drum Roasting

In this procedure, the green coffee beans are put into a cylindrical drum with a rotating shaft and a heat source underneath. This heat source can be either a flame or an electric current. This machine roasts the green coffee beans by blowing hot air through the cylinder. The beans are heated evenly by the hot air blown from the centre of the cylinder.

The time needed to roast green coffee beans by the drum roaster method is usually between 15 and 45 minutes, depending on the degree of roasting preferred by the roaster.

Hot Air Roasting

This method is the most popular roasting method in some parts of the world because it is the most energy-efficient. This method involves roasting the green coffee beans in a large roaster with a system of hot air that constantly blows through the beans as they tumble and rotate.

Hot air roasting, unlike drum roasting, is characterised by its constant use of a fan. Hot-air roasters can be distinguished from all other machines because of their continued use of a fan powered by the electricity from the wall outlet. The beans are heated evenly by the hot air blown from the centre of the cylinder.

Hot air roasting gives off a smokeless and odourless roasted coffee, which is very attractive to the consumer. This method is also easy and convenient for the roaster because it does not demand as much physical labour and time as drum roasting does.

How Flavor Is Affected by the Roasting Method Used

To understand the difference between drum roasting and hot-air roasting, we must know how each approach affects the flavor of the roasted beans.

Drum roasting is a longer process, meaning that the roasting time will be longer than in the hot air roasting method. Because of the longer roasting time, the roasted beans will develop more carbon dioxide, escaping during the roasting process. This gas release causes the roasted beans to expand.

On the other hand, hot air roasting is a faster process because the beans are roasted within six minutes. Hot air roasting causes a higher surface area to volume ratio, resulting in more roasted flavour compounds.

Get Caffeinated!

Drum roasting is a more energy-intensive process. However, drum roasting is not as fast as hot air roasting, resulting in fewer roasted flavour compounds. Now that you know their distinctions, you’ll have a newfound appreciation for the roasting process that goes in every cup.

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