A Home Brewer’s Guide to Indonesian Coffee

Indonesian coffee has had its time in the coffee industry and continues to innovate. The Dutch brought coffee to Indonesia in 1699 and it has since become their main crop. 

Because of their unique landscape, terroir, terrain, all the coffees they’ve grown there have a unique flavor to them. This is not just because of the unique varietals and weather conditions there. It is also due to the unique processing they’ve created called “Giling Basah”, which translates to ‘wet-hulled’ processing. 

In this guide, we’ll discuss everything you need to know about Indonesian Coffees as a home brewer – from how they taste, to how they are grown and produced, to some ways you can brew them, and everything else in between.

The Flavor Notes of Indonesian Coffee

Indonesian coffees have a very distinct flavor and mouthfeel because of their processing method, Giling Basah (wet-hulling). A lot of people describe Indonesian coffees as “herby” or “vegetal”. But it’s not like other “vegetal” flavors that normally describe very raw flavors like biting green lettuce. Think of this “vegetal” flavor more like a cooked vegetable or stewed leafy green. 

There are a few coffees in Indonesia that are non-gili basah processed. These are normally use either natural or honey processing. There are a few producers that also do fully-washed processing. But this is even more rare than natural or honey-processing. 

The natural-processed ones have heavy fruit flavors and can have some of the funky flavors characteristic to that processing method. Meanwhile, the honey-processed ones are clean, sweet, and have a nice acidity.

Visually, most Indonesian coffees can be associated with the color green. Other colors we can use for this origin are beige, red, and even yellow. These are more for the natural and honey-processed coffees.

What to know when buying Indonesian coffee

As with all coffees, the more traceable, the better. When it comes to processing, try to look for coffees that are processed using the natural, honey, and hydro-natural methods. 

While I’ve tasted good coffees that were wet-hulled, I don’t gravitate towards them as much because they are hard to deal with, in terms of roasting. They normally impart vegetal and unfavorable bitter flavors that need a lot of careful attention to not bring out in the roast. 

That being said, I still think that it’s important to taste giling basah-processed coffees, take stock of the experience, and have that as a future reference. 

Seasonality

Because Indonesia is composed of different islands that experience varying degrees of humidity, harvest times are more spread out per region. There are enough regions that harvest at different times – making Idonesian coffee in season virtually for the entire year. 

Region	Harvest Period
Sumatra	January to March
Timor	May to September
Java	July to September
Sulawesi	July to November

Common varietals

• Java
• Bourbon
• Caturra
• Typica
• Catimor

Indonesia used to exclusively produce Arabica coffee. However, leaf rust became a big issue for most producers over the years. This prompted many of them to shift their production to mainly Robusta coffee. Now only 25% of Indonesia’s coffee production runs on Arabica varietals. 

Coffee processing

• Washed / Wet-Processed
• Natural / Dry-Processed
• Honey
• Giling Basah
• Kopi Luwak (Civet Coffee) 

Processing makes a huge impact on most coffees. Indonesian coffees are no exception. You can have the same farm and use the same varieties but you’ll get very distinct flavor differences from the processing method alone. 

In this case, the natural-processed coffee will taste very different from the honey-processed one, and that will also taste very different from the wet-hulled coffee. But, you’ll easily spot the wet-hulled one from the other processing methods because they’ll carry earthy and herbal flavors instead of fruity flavors. 

Giling basah has some similarities to fully-washed processing methods. Many growers still “wash” their coffees to remove the seed from the coffee cherry. But the difference lies in how the coffees are processed after. 

After the coffee cherries and mucilage are removed from the seeds, the coffee is briefly dried then either offered for sale at a local village market or delivered very wet (at 30 to 50 percent moisture content) to a nearby collection station. Afterwards, the coffee is hulled and re-dried until it is dry enough to store without rotting. 

Kopi Luwak (Civet Coffee) is another form of processing that originated in Indonesia and is mainly produced in the islands of Sumatra, Java, Bali, Sulawesi, and in East Timor. This method involves roasting the defecated coffee cherries previously eaten by an Asian Palm Civet. 

Civet coffee has built a reputation for being a novel rarity. A 40-gram bag can run up to $43. At more than $1per gram of coffee this can even cost more than some of the most expensive Geisha coffees in Panama. In terms of flavor, they share a similar earthy and herbal profile common to Indonesian coffees. 

Kopi Luwak as a processing method, however, does raise ethical and traceability concerns. This is mainly due to the intensive farming methods where the civets are placed in battery cages and are force-fed the coffee cherries. It’s for these reasons that many roasters in specialty coffee do not support this processing method. 

Farming conditions and how they affect your cup

Along with the unique processing method that was cultivated early on, Indonesia has a good coffee culture. The Indonesian government and non-governmental organizations (NGOs) are aware that coffee is a big cash crop for them. 

Coffee is also a cultural thing for Indonesia because of how well known their coffees have become. Because of these, a lot of farmers get support in the form of subsidies. 

Indonesia is a very humid country. Wet-hulled processing was invented in the first place to compensate for the humidity there. Giling basah creates enough moisture content so the coffee does not rot. However, the overall humidity in Indonesia still causes problems.  

Most farms are not able to fully do natural or honey processes because those run the risk of the crops rotting. The few farms that are able to do these have special facilities to compensate for the humidity. 

Washed processing is also not as viable an option because water is a bit of an issue for many producers. Only a few producers can afford to have huge amounts of water brought in. They would also need more funding for the proper infrastructure to adequately produce fully-washed coffees.

Brewing guides

Pour Over

If you have a lighter roast, use higher temperatures but try not to go above 200°F / 94°C. The key is not to push extraction as far as possible. Otherwise, you might still get some of the flavors characteristic of the wet-hulled processing. 

Aim for shorter brew times with these coffees. For a 15g – 20g dose of coffee, a total brew time of between 2:15 to 2:35 would be ideal for pour overs. Use a flat-bottom style dripper like the Kalita Wave or the Blue Bottle Dripper to maximize the sweetness and body of these coffees.

Be as gentle as possible with these coffees by not aggressively agitating them throughout the brew. Approach them with very gentle pours that line up with the roast level. 

Immersion

Do a cupping or brew a French Press using James Hoffmann’s method. 

Espresso

*observations on these ratios were made using light to medium degrees of omni roasts

Indonesian coffees can take longer ratios for espresso and still retain a stable flavor profile. You can push ratios between 1 : 2.7 to 1 : 3 and it would still be good with milk. 

For straight up espresso, try using ratios between 1 : 2.5 and 1 : 3. 

Indonesian coffees are known to have a good and heavy body to them. That’s why they are a good staple for blends because they add a good mouthfeel. 

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