A Beginner’s Guide to Roasting Coffee

Hot or iced, no matter how it is prepared, nothing beats a good cup of your favorite coffee. Whether it’s your morning pick-me-up or your go-to drink at any time of the day, coffee is certainly a part of many people’s lives. Every year, over 400 million cups of coffee are consumed worldwide, making it one of the most widely consumed beverages.

Many people enjoy drinking coffee for a number of reasons, including the fact that it awakens our senses and keeps us energized, that it is an excellent source of antioxidants, and, of course, that it has an amazingly good flavor and aroma.

But have you ever wondered about what coffee beans go through before they reach our cups? 

The coffee that we all enjoy takes a long journey before it reaches our cups. Behind every sip is a labor-intensive process carried out with passion and precision by coffee growers, millers who meticulously remove the fruit and dry the beans, those who clean and grade the quality of the beans, to those who roast them, and lastly the consumers and baristas who grind them.

Before coffee beans can be ground or brewed into the coffee we all know and love, they must first be roasted. Unroasted coffee beans, also known as green coffee beans, range in color from greyish green to yellowish-green and have a beany and grassy scent that does not smell like coffee at all.

Related: Mistakes You Can’t Make When Handling Green Coffee


What is coffee roasting?

Roasting is the process of turning green coffee beans into flavorful brown ones. It is a rigorous heating process that changes the physical and chemical properties of coffee beans. It is an important step in the coffee-making process because it brings out the aroma and flavor that are locked inside the green coffee beans.

There are several methods for roasting these beans, and each has a different effect on the flavor of the finished product. There are three major stages to it: drying, browning, and development or roasting.


The Roasting Stages


Since green coffee beans have a high moisture level of around 8-12%, the first stage of roasting is to dry out the moisture in the bean. The stage starts when the coffee is charged into the roaster and finishes when the coffee's color changes from green to yellow.

With a traditional drum roaster, the drying stage normally lasts 3 - 8 minutes, but this still depends on the number of beans, the larger the batch the longer time it takes. Controlling the temperature of the roaster is crucial for preventing over or under-drying of the beans, which can impact their overall quality.

Related: Importance of Moisture Content in Coffee Processing


This is where the Maillard reaction takes place; it is a series of chemical reactions that are critical in developing the flavors and brown color of roasted coffee. The internal pressure increases to the point that it can break the cell walls of the beans, causing them to pop, which is referred to as the first crack, and the development stage begins.

Development or Roasting

The final stage of the roast is responsible for the overall flavor of the coffee, depending on the roast degree and time.  A color meter can be used to measure the roasting degree, which ranges from light to dark. Lightly roasted coffees are typically more acidic, whereas dark roasted coffees are more bitter. The total roast time also affects the coffee’s flavor profile. Roasting the beans quickly produces more desired aroma compounds, but there is a risk of burning them. Slow roasting gives more control over the flavor development of the beans.


Storing roasted coffee beans

Knowing what happens to coffee beans before they reach our cups, the physical and chemical changes that take place during the roasting process, can help us understand how important it is to store them properly in order to maintain their freshness and distinct flavor.

Many things can affect the taste and overall quality of the coffee beans, including air, moisture, heat, and light, all of which can speed up the staling process of the beans.

During the roasting process, coffee beans undergo a natural process known as "degassing," in which carbon dioxide is released. Once the beans have finished releasing CO2, they begin to collect oxygen and oxidize, so the more it is exposed to air and oxygen, the more the coffee flavor degrades. 

Furthermore, because coffee beans can easily absorb moisture from their surroundings, moisture on the surface of the coffee beans will drain out most of their aroma and flavor.

Another factor is heat; when coffee beans are heated when stored, the oils that are the primary source of flavor quickly sweat out onto the bean's surface. Because these oils are volatile, they evaporate quickly, causing the flavor and aroma to drain away once more.

Exposure to light can also damage the quality of fine coffee beans. When roasted coffee beans are exposed to light, both natural and artificial, UV radiation speeds up the breakdown of the chemical components in the beans. This is process is called photodegradation, and it causes the beans to become stale and less aromatic.

With a better understanding of the effort that goes into producing coffee and the factors that can affect its quality, it is reassuring to know that there is a solution that can help preserve it. With the help of GrainPro Hermetic bags, made from materials with superior air and moisture barriers, no oxygen or moisture can be absorbed by the beans. 

This means that roasted coffee beans remain fresh and that there is no loss in quality or quantity, allowing for the production of more cups of good coffee.


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