A guide to roasting Indonesian coffee beans

Kahwei Yoong
September 3, 2021
roasting indonesian coffee beans

Blessed with an equatorial climate, soaring mountains, and rich volcanic soil, Indonesia is one of the world’s leading coffee producers.

While the majority of production is focused on robusta, the country’s diverse growing conditions and traditional wet hulling processing methods gives its coffees complex flavour notes and long-lasting finishes that work well both as single origins and as a component in blends.

For specialty roasters, Indonesian coffees offer a good opportunity to reach new corners of the market, particularly among those who favour darker roasts.

The subtle differences between coffees from each region mean that consumers will constantly have something new to pick up on, whether it’s the vibrant acidity of Sulawesi coffee or the spicy flavour notes of Java arabica.

To understand more about Indonesian coffee beans, I spoke with Benji Salim, founder of The Q Café & Roastery.

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harvesting indonesian coffee cherries
Coffee has been grown in Indonesia since the early 18th century

Understanding the Indonesian coffee industry

With more than 300 years of coffee-producing history, Indonesia has seen it all.

First introduced in 1696, arabica coffee was being cultivated on the island of Java by the turn of the century and exported by the Dutch as early as 1711, where it became popular in coffee houses across Europe and North America.

As demand ramped up, production spread, with farms emerging in Sulawesi, Bali, Timor, and Sumatra. However, a devastating outbreak of coffee leaf rust in the late 19th century swept across Indonesia, wiping out the majority of arabica cultivar.

In 1900, robusta was brought over as a substitute in an effort to kickstart production. Today, the more resilient species makes up between 80% and 90% of Indonesia’s total coffee production, although arabica is making a steady resurgence.

“[Coffee] has become a big part of the Indonesian lifestyle.”

Benji, the founder of The Q Café & Roastery in Australia is on a mission to promote Indonesian coffee. He is a roaster, certified Q grader, and green coffee buyer who works and sources directly from farms in Indonesia.

He tells me that Indonesia has been experiencing a coffee culture boom since 2016, with a growing appetite for iced coffee.

“When I started exploring coffee in 2010, there were not many coffee roasters or specialty coffee, and we used to have a lot more tea drinkers,” he says. “Now, everyone is extremely knowledgeable about coffee and it has also become a big part of the Indonesian lifestyle.

“On the coffee production side, farmers are getting curious about different processing methods and coffee origins. Technology has also made information accessible for them to explore more about coffee.”

At the same time, however, Benji notes that the development of the industry is still behind other large coffee producing nations such as those in Central America, where farmers had a headstart in terms of learning about processing methods, consumer demand, quality control, and more.

With that being said, the country offers great potential in producing high-quality coffee.

fresh indonesian coffee cherries
Each island produces coffee with its own distinct set of characteristics

The influence of different growing regions

Indonesia comprises more than 17,000 islands, but the majority of coffee production is divided across seven regions: Sumatra, Java, Sulawesi, Flores, Bali, and Papua.

Benji tells me that although all part of the same archipelago, each island produces coffee with its own distinct characteristics.

“Because Indonesia is in the middle of the equator, some of the producing regions are located north, while some are south,” he says.

“For example, West Java is located in the southern part which gives it more sun exposure. The northern part of Sumatra, on the other hand, has a taller elevation, but it is also more humid and experiences more rainfall during harvest, which can create problems when drying coffee.”

Coffee from Java (pictured) is vastly different to coffee from Sumatra

To mitigate the difficulties of drying coffee in humid weather, a processing method known as giling basah, or wet hulling, was developed. Similar to wet processing, wet hulling involves pulping, fermenting, and washing the coffee to remove its mucilage layer.

The main difference occurs at the drying stage: wet processed parchment coffee is usually dried to 10-12% moisture, whereas wet hulled coffee is only dried to 30% moisture content, before being hulled.

“As a nation, we have created something that is unique and closely tied to Indonesia, so there is definitely a need to develop the method better,” Benji says.

“At the same time, there is also a lot more innovation among producers who are doing hybrid processing that involves wet hulling. For example, the wet hulled honey processing (called blue honey) experimented by Java Frinsa Estate.”

In addition to processing methods, the differences in terroir, climate, and growing conditions influence the subtle differences between Indonesia’s coffees.

For instance, Sumatran coffees such as Mandheling and Lintong exhibit more earthy and herbal tones, while Java coffee has a slightly spicy twist with a sweet impression.

“Overall, Indonesia has an extremely wide range of flavour profiles,” Benji explains.

“We tend to have more spice notes compared to varieties of coffee that exist in other regions like Ethiopia or Latin America, because most of our varieties are hybrid. You will also see a lot more local varieties with Indonesian coffee, like Ateng Super or Sigarar Utang.”

Due to the wet hulling processing method, Indonesian coffee beans tend to have a high moisture content

Best practices for roasting Indonesian coffee

When it comes to roasting Indonesian coffee beans, one of the most important factors to consider is moisture content.

For wet hulled coffee, Benji explains that moisture content is usually around 11.45-12%, which is slightly higher than other coffee processes. As a result, more heat is typically required to penetrate the beans.

“I am not afraid to apply high heat but you also need to be mindful that every coffee or variety will behave differently,” he says.

“Also, it will be helpful to check the moisture content before roasting, so you have a better perspective on how to approach the coffee. If you are roasting coffee with higher moisture, you might want to have a longer drying phase so you don’t roast it too quickly, resulting in metallic or green tastes.”

An article by roasting equipment retailer Sweet Maria’s suggests “stretching the drying stage and/or the post first crack stage really helps express the mouthfeel of these coffees better, reducing the harshness and starchiness.”

In addition, Benji emphasises the importance of cupping in helping roasters achieve desirable results.

“You should approach roasting the beans with utmost neutrality and always aim for best.”

“The knowledge of how to cup and the curiosity to taste everything beyond just coffee (so you can relate to coffee) is extremely important,” he says.

“If you don’t understand how to cup, what it means to cup or what the flavour means to the customer, it is going to be very difficult to make good coffee or to promote any coffee around the world.”

While one of the strongest attributes of Indonesian coffee is its body and mouthfeel, the quality of flavour depends on the score of the coffee.

Therefore, experimenting with different roasting styles and making adjustments along the way helps in achieving a roast profile that highlights the coffee’s best attributes.

Finally, roasting Indonesian coffee also comes down to having an open mindset. While there are preconceived notions surrounding Indonesian beans, roasters should be mindful not to allow biased opinions affect their motivation in exploring coffee from this origin.

As Benji advises, “Do not be afraid of Indonesian coffees; it does not have to be a very stressful experience just because you have never roasted Indonesian beans before. Like blind cupping, you should approach roasting the beans with utmost neutrality and always aim for best.”

compostable coffee bag
Using packaging to showcase origin is of the utmost importance for specialty coffee roasters

After all the hard work and effort put in roasting to bring out the best flavours of coffee, the next crucial step is to choose packaging that preserves and safeguards all those qualities. 

At MTPak Coffee, we offer a range of sustainable packaging options that keeps your coffee fresh and protects all its unique characteristics. Our high quality coffee bags can be fully customised, from material and bag structure to design and features, helping showcase the coffee in all its glory.

For information about our compostable coffee bags, contact our team.

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