Is there anything better than learning about coffee? Well if your answer is no, then you are in the right place. Over the next month or so I will be writing on a few different processing methods, what affect they have on the coffee and why different methods are chosen.
When I first started learning about different processing methods, tasting coffee’s with these methods and reading about it, it really amazed me the difference it made to the final cup. The more you read and learn about this, the more you realise how important this stage is, for the roaster, barista and consumer, as the processing directly affects all of their experiences with the coffee. I have had the pleasure of sampling the same beans side by side from one grower, all processed differently to really see the effects, it’s genuinely quite amazing the difference it makes.
So let’s dive into today’s method, we are starting with a really interesting one, giling basah, or otherwise known as wet hulled processing. This process is exclusive to Indonesia, and especially common within Sumatra and Sulawesi.
Wet hulled coffee and wet processed coffee may sound very similar but they yield very different results, so it is important to not get these two confused.
The process of wet hulled coffee is:
The coffee cherries are picked.
They then go through a pulping machine, removing the fruit from the bean, leaving some mucilage and the parchment.
The coffee beans are then placed in concrete tanks or plastic rice bags overnight to ferment. This helps break down the pectin in the mucilage aiding with removal.
The next day the mucilage is removed by washing the beans, leaving a wet parchment exposed on the bean (up until this point, the process is very similar to washed process coffee).
The beans are then sun dried for a few hours up to 1-2 days, to let the parchment dry slightly. The moisture content will now be around 20-24% ready for the wet hulling. At this moisture level the beans are still swelled with water and soft to touch.
The beans are placed into the wet hulling machine, this is much larger and creates more friction than traditional hulling machines, because the parchment is harder to remove when moist.
The hulled beans are now dried in the sun during the day, then packed into bags at night until they reach a moisture content of 12-13% this normally takes 2-3 days.
This method is far from conventional, and some would say over complicated with added risk factors, all of which is true. Though with that being said, there is reasons this method is used in Indonesia.
This method was the traditional method for coffee from Indonesia. Coffee was first introduced here in 1699 by Dutch colonists, their motivation was for financial gain not for enjoyment of the product itself. Wet hulled processing is much faster than more traditional methods, approximately 2-3 times faster than other methods in their suited climates. This means they could sell the beans at an earlier timeframe and get started on the next crop increasing revenue. This method would most probably still have become a chosen method for the area due to their climate. The Sumatran climate is between 70-90% humidity year round making it very difficult to dry coffee with other methods. Extended drying periods can cause spoilage of beans in wet climates.
While this hot, wet climate may make it difficult to process coffee, it also creates perfect growing conditions for coffee. While they do have two distinct growing seasons (March - May & September - November), trees can be harvested all year round, increasing the need for a quick processing method.
Wet hulling process is not short of its downfalls either. Unfortunately a lot of the beans grown here and processed this way are of low quality. Lots of growers dry this coffee in non optimum conditions (ie. On the side of the road, on tarps), use old badly maintained equipment and with less knowledge and education resulting in higher chance of defects. The wet hulling machines themselves can damage beans quite easily. Due to the extra friction requires and how soft the beans are at this point, there is often damage to the tips of the beans. This damage or defect is known locally as kuku kambing, which translates to goats nail, describing the split in the tips of the bean.
Roasters require extra knowledge and attention when roasting this coffee. The extra moisture content held in the bean, needs more heat in the early roasting stage to fully dry the bean out and achieve first crack at the desired time of roast. Failing to do this can result in a sour, unbalanced and undeveloped cup. This coffee lends its self to medium and medium-dark roasts, helping bring out some sweetness and the chocolate flavours in the coffee.
It isn’t just the roaster that needs to pay extra attention with this bean, some small tricks and tweaking to the extraction process can improve chances of a tasty cup. It is recommended for barista’s to lower the temp of their brew water slightly to help bring sweetness into the coffee. I tend to not let my extractions go very long with this type of coffee, usually aiming for something like 21g/24sec/44g out, with brew water of 91-92c. This will be dependant on the roast and bean I’m working with, yet this would make a good starting reference for anyone wanting to give it a go. Shorter brew times work well with this coffee due to its low acidity and naturally syrupy full body.
Yes, these types of coffee’s have some downsides, yet they can have some great upsides too. They are extremely full bodied, making them highly sought after for blends, often paired with Ethiopian coffees or South American coffee to balance it out. Even as much as 10% Sumatran wet hulled coffee can increase the body of a blend, helping to carry flavours and characteristics of other origins.
If you take the time to find high quality coffees with this process method, where care has been taken throughout the whole process from growing, processing, storing and roasting, it can be a real delight to try. They can have a beautiful herbal, spicy complexity with a smooth full body and a gentle sweetness.
Specialty coffee applications have not taken off in Indonesia as much as in other countries, yet there is some growers doing amazing things. It really helps to drive these growers and others to do the same if us as consumers can show support and demonstrate that there is a market for them. The next time you have a chance to try a high quality wet hulled coffee, or in fact any high quality sustainable coffee from these regions, give them a go. It may end up being your new favourite.
Thanks for making it to the bottom of this lengthy article! You must be a true coffee lover just like myself.
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