Indonesia is the fourth-biggest coffee producing country in the world, behind Brazil, Vietnam, and Colombia. 

After coffee leaf rust wiped out most of the high-quality arabica varieties in the late 19th century, the country switched to robusta as a substitute in 1900.

Today, roughly 25% of the coffee produced in Indonesia is arabica, but only a tiny fraction of that is specialty. And while the climate in Indonesia is suitable for coffee production, its comparatively low altitudes make it difficult to cultivate some of the more prized and sought-after arabica varieties. 

To make the flavours in their coffee more distinctive, some producers are instead using innovative or experimental processing methods to develop more complex flavours. I spoke to three different producers to learn more.

Lee este artículo en español Tres Métodos de Procesamiento de Café Innovadores en Indonesia

Carbonic Maceration At Karana Spesialis Kopi 

First, I spoke to Rodney Glick, Director of Coffee at Karana Spesialis Kopi. Karana has recently added carbonic maceration to its coffee processing.

Carbonic maceration is a processing technique that was first introduced by World Barista Champion Saša Šestić in 2015. It originates from the winemaking sector, and has since been adapted to suit specialty coffee.

Carbonic maceration involves sealing coffee cherries in an airtight container with a one-way valve that allows for the release of pressure and oxygen. After being flushed with carbon dioxide, the cherries are sealed in the tank, and its temperature is closely regulated.

Carbonic maceration creates complex and unusual flavours in a coffee. It requires a lot of time and energy, however, and if the temperature is not properly controlled, it can lead to the whole tank being discarded and wasted as a result. 

Carbonic maceration is not a method in itself, but rather an additional step that can be added to either washed or natural coffee processing. With washed processing, the cherries are depulped before being introduced to the tank; with natural/honey processing, the cherries are sealed first, then dried as normal.

Rodney says: “Fermentation techniques used in winemaking are unfamiliar in a lot of coffee producing countries, including Indonesia. Historically, countries that grow grapes haven’t grown coffee, so until recently, linking fermentation methods between the two products wasn’t obvious.”

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Rodney adds that Indonesia’s tropical climate makes fermentation quite difficult to control. He says that when humidity and moisture levels aren’t controlled, the coffee can overferment. “When dried without enough sun, fermented flavours turn vinegary and sour.”

At Karana, Rodney has added carbonic maceration as a step used for their natural processed coffees. While this has been popular in other countries around the world, Rodney tells me that it is viewed as highly experimental in Indonesia.

Rodney says: “So far, little is known about this technique and its outcome… it’s the perfect opportunity to create new flavours, but [in Indonesia], it’s also risky because the season is only three to four months long. 

“Cherries are only available for a brief period, and a substantial investment is required to fund research like this. There are also no second chances, as it’s impossible to reverse over-fermentation.”

For this reason, Rodney regularly cups and evaluates his coffees to gauge and judge the role that carbonic maceration plays.

Terroir-Specific Fermentation At So So Good

All coffee undergoes some degree of fermentation. It begins at the moment the cherries are picked. The terroir of a coffee-producing region has a significant impact on how fermentation occurs, and how it influences the flavour profile of the resulting coffee. 

As well as factors like elevation and soil quality, terroir also includes the natural yeasts and bacteria present in a certain region. During fermentation, these microorganisms consume the sugars and acids present in the coffee cherry. This process ultimately affects the flavours which will be present in the cup once it is roasted and brewed.

The “microbial terroir” (the microorganisms present in a certain producing region) is just one of a countless number of parameters which affect the flavour of your cup.

In 2020, Mikael Jasin launched So So Good, a coffee company that works directly with specialty producers in Java, Bali, and Flores. Mikael tells me that So So Good uses “terroir-specific” fermentation starters.

A fermentation starter is effectively a culture of yeast that is intentionally introduced to “kickstart” the fermentation process and guide it in a certain way.

“We want to isolate the dominant yeast [present in the region] and create several starters based on it,” Mikael tells me.

In order to do this, Mikael and his producers send fermentation water samples to the Bandung Institute of Technology to be analyzed and measured. Each producer then receives fermentation starters that are specific to their terroir.

“What we’re doing is reverse-engineering the way we produce coffee,” Mikael explains. “So, first, we taste the coffee. Then we look at how the fermentation is going to affect it. We aim for a specific taste profile, and this helps us decide which fermentation starters we use.”

By using terroir-specific fermentation starters and monitoring the pH level throughout fermentation, producers get more control over the outcome of their product. The impact, Mikael tells me, is significant. 

He says that two fully washed coffees from totally different regions can taste similar if the right fermentation starters are used to “guide” the coffee to a certain flavour profile. Conversely, without fermentation starters, coffees from similar regions may taste incredibly different even if they are grown and processed similarly.

Experimenting With Lactobacillus & Yeast At Frinsa Estate

Fikri Raihan Hakim of Frinsa Estate is one of the few coffee farmers and processors in Indonesia who promotes and sells single varieties. “We began planting new coffee trees in 2011,” Fikri tells me. “And we are very adamant about having one lot for one specific variety. 

“When workers pick, each variety is put into its own bag. And at processing sites, each variety has its own area.” 

Even though it’s common for coffee farmers to plant several different varieties to manage their farm sustainably, most of the time, these different varieties are processed together in a single batch. 

Currently, Fikri has more than 14 varieties growing on his farm. They include Ateng Super, Borbor, Andungsari, Timtim, Lini S, and Typica. “All seeds are obtained directly from the Indonesian Coffee and Cocoa Research Institute (Puslitkoka),” he says. 

Fikri believes that by isolating and carefully keeping the single varieties separate, he ensures consistency and traceability. By doing this, he says that Frinsa Estate provides roasters with precise, detailed information about their beans. 

In 2019, Fikri and his father, Wildan, experimented with lactobacillus and yeast in collaboration with Nordic Approach. Fikri tells me that the particular lactobacillus he uses is isolated from the digestive system of the Asian palm civet, which is used to produce kopi luwak coffee.

Kopi luwak coffee, mainly produced in Indonesia, is made by feeding coffee cherries to a cat-like mammal called the Asian palm civet.

These coffee cherries are then partially digested, and the beans are passed whole in their faeces. These beans are then separated, cleaned, and sold to be roasted. The digestive enzymes in the civet’s gastrointestinal system cause the coffee to start fermenting.

However, while this method has drawn a lot of media attention, its effect on the resulting flavour is up for debate. Many believe kopi luwak coffee to be little more than a gimmick, with the Specialty Coffee Association of America even saying there is a “general consensus… that it tastes bad”.

However, using the isolated lactobacillus alone, Fikri has managed to yield unique flavours. He tells me that his natural coffees are made by adding the bacteria and the yeast after the cherries are cleaned.

They are then placed in plastic bags, where they ferment anaerobically (without oxygen). Fikri tells me that the resulting coffee has notes of sweet spices and fruit candy. 

With a climate that makes producing sought-after varieties difficult, Indonesian producers must look to other methods to set their beans apart and create high-scoring coffees.

While these methods might not be unique to Indonesia, they are certainly interesting, and unusual for the country. Whether or not they become more popular remains to be seen, but one thing is for sure: it is certainly a sign of innovation in Indonesian coffee processing.

Enjoyed this? Then read Coffee Fermentation: What Is It & How Can It Improve Coffee Quality?

Photo credits: Wirasathya Darmaja, Karana Spesialis Kopi, So So Good, Frinsa Estate

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