Indonesian coffee and its process Giling Basah or wet threshing

The Origin of our Cup of Excellence VII: Bali Giling Basah

Origin of the variety: This coffee comes from the Buleleng region, in the highlands of the island of Bali (Indonesia). It is an estate coffee, traced back to the Sukasada estate, located between 1300 and 1700 metres above sea level.

In our quest for the ultimate cup of excellence, we try coffees from all over the world, and some of them catch our attention in a powerful way, such as this coffee from the island of Bali in Indonesia.

Bali is a volcanic island in the Pacific, famous for being a colourful and paradisiacal tourist destination. But in 1963 it also became sadly known for the eruption of the Mount Agung volcano, which caused the death of thousands of people and extensive material damage, including to the coffee plantations. But after the catastrophe came reconstruction, and taking advantage of the fertility of the land, small farmers promoted the cultivation of quality Arabica coffees all over the island, as was also the case in other regions of Indonesia, such as Java, Sumatra and Sulawesi.

Organic farming and shade coffee: In Bali almost 100% of the producers are organic farmers. Mostly shade-grown, i.e. coffee is grown alongside other varieties of taller trees with thick foliage, which reduces the exposure of the groves to the sun by 30-50%. 

This favours significant populations of indigenous birds in the crops, which are beneficial as they act as a "natural pesticide" against pests that can affect the coffee bushes. As a result, no chemical pesticides are used in Bali whatsoever. It also happens that in the 1990s a lot of orange and mandarin trees were planted, and the citrus notes of their fruits are also carried over to this coffee.

But what really sets this coffee apart from all the rest and gives it a special personality is what is known as Giling Basah, or wet threshing. And what it is: it is an accelerated way of drying the coffee and separating it from its parchment when the bean is still wet (20-25% humidity). This is done to accelerate the drying of the coffee, which is very important given the high humidity of the climate in Indonesia. The result is a full-bodied, complex, slightly acidic and fruity coffee. 

How is wet threshing or Giling Basah done?

This is a threshing method used almost exclusively in Indonesia. The coffees from Sumatra, Sulawesi or Bali that have been processed using this method are famous. The reason for this exclusivity: the extremely humid climate in this part of the world. The result in the cup: a full-bodied coffee with a slight acidity... but be careful, Giling Basah is not easy, and the possibility of damaged beans is high. You have to choose your coffees very well if you don't want to get an unpleasant surprise.

But let's take it one step at a time: what is wet threshing? Or even simpler:

What is threshing? How is the process done?

We must not forget that coffee is initially a cherry, and we have to turn it into a couple of dry beans, which are what we need to make coffee. That is why we have to take out everything that is in the bean (the pulp, the mucilage and the parchment). This process is called Beneficiado or processing, and broadly speaking there are three types: natural, washed or wet and honey.

What about threshing? Threshing is the last part of processing, which consists of separating the parchment from the grain. It is normally done once the grain is dry (11% moisture content) and hard, as this makes the skin, which is very dry and fragile, much easier to remove, and the grain, which is very hard, is practically unbreakable during this process.

Wet threshing is a nuisance, as it occurs when neither the grain nor the parchment is dry. In other words, the parchment is much more stuck to the grain, and the grain has much more humidity (between 20-25%), is soft and breaks much more easily. As the parchment is much closer to the grain, the process is more complex and requires more energy and friction... and the result is not as homogeneous.

What are the steps prior to the threshing process?

It all starts with the harvesting of the berries. On the same day that the cherries are picked from the bush, they are put into a (small, simple, custom-made) pulping machine that removes the pulp from the berries. This was the easy part, as the berries are still covered with mucilage and parchment. 

To remove the mucilage, the beans are left overnight in a water tank or, failing that, in polypropylene bags, which is the most common method. Before closing the bag, as much air as possible is removed. This helps to break down the pectin present in the mucilage, which facilitates the removal of the mucilage.

The next day, the beans are washed with water and the mucilage is removed. The beans are then left to dry, but unlike the usual wet processing, they are not dried for two or three weeks until they reach 11% humidity (and are easy to thresh), but rather, and this is the crux of the matter, they are only dried for 2 to 3 days (no more!), until they reach a humidity of 20 to 25%. In other words, we save a few days of drying.

Then we have what is also known as Labu, i.e. a wet coffee bean covered by a layer of semi-dry parchment. 

Now we need to thresh (separate the parchment from the bean) and for this we need a much bigger and much more powerful machine, which generates more friction than the usual dry parchment threshing machine, as the semi-dry parchment is much more sticky than usual and is more flexible. 

These machines run with water and this makes the semi-dry parchment stick to the grain more, and also this grain is much more fragile and softer, to the point that it can be crushed with the finger. 

The result is that in many cases the parchment does not come out at all, and there may also be broken grains at the ends, due to the low density of the grain. 

These grains are dried until they reach the desired moisture content (and hardness), which is slightly higher than when dry threshing. Thus, we normally aim for a moisture content of 11%, but in this case we will dry them until they reach 12-13% moisture content. The beans are dried in the sun during the day and in polyethylene bags overnight. All to speed up the drying process, which is what it is all about.

The result is dark green and somewhat uneven grains.

Why is this threshing process done in Indonesia?

It is not a matter of taste, but of necessity. When processing (and not threshing!) coffee, it is essential that the coffee is dried and ventilated under optimal conditions. For this you need sunshine and not too much humidity, otherwise the process would take too long and the bacteria would cause fermentation defects that would be noticeable in the cup..... Conclusion: if it rains you have a lot to lose!

What happens in Indonesia? Well, they may be beautiful islands, but they have an annual rainfall of more than 2000mm, a relative humidity of around 70-80%, and are prone to typhoons and torrential rains. So farmers have to do everything in their power to shorten the drying time. 

They do this by using polypropylene bags and removing the parchment before drying. By not having this layer that protects the beans in normal drying, the beans without parchment dry much faster (it is like drying with wet clothes, or without), so that the whole process is 2 to 3 times faster, i.e. what you would do in a dry climate in 3 weeks, in Indonesia is done in one week.

How does Giling Basah taste in a cup?

Well, if it is well made and uniform, it is a coffee that is characterised by a full body, a fruity and complex touch, with a light acidity.  

I hope you have enjoyed this explanation and that it has been understood... and if you have been left with the desire to drink a good Giling Basah coffee, now is the time, if you are quick, with the Bali cup of excellence from Cafés Caracas, which you will find in our online shop. Don't let it slip away!

Tasting note for the taster:

This is a cup that will surprise you with its great sweetness, with an intense and prolonged aftertaste. With citrus notes of mandarin. Full-bodied, very complex in flavours and light acidity.

Tasting note for the roaster:

These coffees are also a bit more difficult to roast. One of the most important parts of roasting coffee is dehydrating the beans to ensure that they can reach first crack at the appropriate time. 

These beans tend to have a moisture content of around 10.7% -11%, or higher. This is about 1% more moisture compared to other coffee methods, so you will need to heat the coffee a little more at the start of roasting. If you don't dehydrate your coffee sufficiently, you will end up with a coffee that is inconsistent in terms of flavour, astringent, unbalanced and sour; not exactly the ideal profile for a coffee.