All about Sumatra
What is Sumatra Coffee?
Before I go racing on ahead it’s probably a good idea to do a quick overview of Sumatra coffee so you have a better understanding of this unique bean.
Cultivated from the lush Indonesian island we know this bean for being full-bodied with a smooth mouth-feel and spicy flavors of dried herbs and earthy notes.
Plus, this coffee has almost no acidity making it the perfect choice for anyone with a sensitive stomach.
You will almost always find Sumatra in some of the best coffee blends due to the unique flavor profile these earthy, spicy, and herbal beans can bring to the mix.
Where Do Sumatra Coffee Beans Come From?
If you hadn’t already guessed Sumatran coffee beans come from Indonesia, more specifically the Sunda Islands; and it’s not just one island. The Islands of Sunda are a small group of islands that are tucked away on the west coast of Indonesia. Sumatra is an out-of-the-way place and can be difficult to get to, because of the remote location almost all the coffee growing landscape is rural and happens on a small scale.
The largest of the islands are named the Sumatra island (Sumatera in Indonesian) and the coffee grown in this region has proudly inherited the name. Much of the landscape on this remote rugged island is fertile, and the soil is enriched with leftover ash deposits from one of the earth’s largest volcanic eruptions.
The location of the Sunda Islands couldn’t be any better and they’re in what coffee aficionados call the coffee green belt. It’s the perfect mix of tropical weather combined with hot and humid conditions make for some of the best coffee growing regions in the world.
What Makes Sumatran Coffee So Special?
There are two main reasons why Sumatran coffee is so special.
Small Family Run Sumatra Farms
The first reason why this bean is special comes down to the remote location and the rugged landscape so almost all (if not all) of the cultivation is done by hand and on a small scale.
In fact, virtually all the coffee grown and processed in the Sunda Islands is done in small family plots or even in backyards. It’s also worth pointing out that most of the planting, growing, harvesting, and transporting of the coffee is carried out by women.
The cherries are meticulously handpicked and sundried (often on the patio of the family home) and sorted up to three times to ensure that any defects are removed and don’t make it into the final product.
Wet-Hulling Processing Method (Giling Basah)
The second reason is due to how the coffee is processed. Almost all of Sumatran coffee uses a unique traditional wet-hull processing method (or Giling Basah in the local Bahasa language – translated from Indonesian, the term means “wet grinding”).
Before they can roast the coffee beans they have to go through a processing method that will turn it from a fruit into a dry green bean. There are many ways to do this but the most popular methods (which are natural processes) are washed, wet, or honey.
However, don’t confuse wet with wet-hulling as both methods are not the same even if the name implies similarities – the final cup characteristics are different.
How Does Wet-Hulling Work?
If we start right at the beginning.
Inside every coffee cherry, you’ll find a bean, a layer of parchment, and mucilage. The term hulling is the process to remove the parchment layer from the bean.
The removal of each layer is done separately and typically requires three or more separate processing stages. Initially, processing the “wet-hulled” coffee up to now has been almost identical to the wet method.
However, when it comes to drying the beans, the other coffee-producing countries using the wet method would require that the beans dry until there’s at least 11% moisture content left – this can take many days and the beans are fairly dry at this stage.
Dry beans are easier to process because the parchment layer is brittle and can be removed much more easily when the beans move onto the next stage.
This is where the differences become clear.
Due to volatile weather in Sumatra farmers only have a limited window before the rain pours down. So, the wet-hulled beans are sun-dried for only 3 days which leaves the moisture content at around 20-24%.
With so much moisture still left the bean is inflated with water and soft to touch and if you were to poke the beans firmly with your finger, they would be easily crushed – but the parchment layer is almost dry.
Due to the moisture and the delicate soft bean, a special huller machine is used that’s designed to process semi-dried parchment. This machine requires more power since removing the damp parchment that clings to the bean thus making it harder to remove and requires much more friction to get the job done.
During this stage, the hulling machine also helps ferment the coffee beans which in-turn creates a complex earthy flavor that Sumatran coffee beans are known.
The beans are then left in the sun to dry and stored in bags during the night to help with the fermentation until they have roughly 12-13% moisture content.
Simply put – wet-hulling leaves coffee moister for longer
Remember that most of the coffee processing is carried out by hand – so you can only imagine the amount of work involved to keep coffee lovers around the world stocked up with their favorite Sumatran coffee!
That’s it in a nutshell.
There is a lot more to the entire process which could warrant an entire article dedicated to it. But hopefully, this gives you a quick and easy-to-understand overview of how wet-hulling is done in Indonesia.
Sumatran Wet Hulling Produces Unique Characteristics
Due to the nature of this multi-stage processing method and the fact that most of the cultivation and processing is done on such a small scale – even down to using homemade hulling machines and many roasters opt for a dark roasting which helps to counteract and mask the high variance found in this particular origin.
It’s this wet coffee processing that gives Sumatran coffee its unique characteristics, flavors, and aromas. Other coffees are known for their notes while Sumatran can be characterized by their full bodies and low acidity.
The flavor profile is completely its own, and that’s what makes this Indonesian origin of coffee so unique. So, don’t be surprised if you pick up flavors and aromas of mushrooms, damp soil, moss, and just general earthy tones.
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