Regardless of the type, variety, region of origin, quality, or other factors, all coffee beans are processed
using one of three methods (or a combination of them):
1. Dry, also called natural.
2. Semi-dry/semi-wet (also known as “honey”).
3. Washed.
Description of Coffee Processing and Drying Methods
In the first case, after sorting (when unripe and low-quality cherries are removed), the coffee cherries are
immediately laid out under the sun to dry. Nothing else is done—no removal of pulp or skin, no washing. However,
since this process can take up to two months (depending on the weather conditions at the drying site), it is often
accelerated by using electric, gas, or wood-fired drying drums, where the entire process is completed in just hours
or 1–2 days instead of weeks or months.
In the second case, after sorting, the cherries undergo pulping. If only the skin and the mucilage layer
beneath it are removed, the method is called “honey.” If the pulp and deeper layers closest to the bean are also
removed, the method is called “semi-washed,” “semi-wet,” or “semi-dry.” Depending on what each producer
chooses during pulping and subsequent processing, this method can be divided into numerous variations with
different names.
The washed method is the most common because it is simpler, faster, cheaper, and more versatile than the
others. In this method, sorted and fully pulped beans are washed under water pressure, being turned and rubbed
for hours until they are completely stripped of all layers that naturally surround them inside the cherry. Most
producers then use semi-dry or wet fermentation as the next step, during which the beans “mature” as a
commercial product, acquiring a more consistent flavor and aroma, as well as clearer expression of certain
organoleptic qualities.
So, beans processed by the dry method are almost always sweeter than those produced by other methods.
Why is that? We’ve looked into it and present the main factors below.
Why Does the Dry Method Produce Sweeter Beans?
Research into this question began about 70 years ago, when the difference was first noticed and confirmed.
The earliest hypothesis was that sugars contained in the skin, pulp, and mucilage of the cherry transferred
into the bean during drying through chemical diffusion.
Another assumption was that during washing, part of the sugar on the bean’s surface layer was washed
away, and subsequent fermentation amplified this effect through sugar breakdown.
The most up-to-date and widely accepted explanation today is no longer a hypothesis but a confirmed fact:
beans processed with water actually begin to germinate.
Germination and Sugar Loss
The germination process of any seed (not just coffee) is a complex, multi-level natural mechanism—one of
the most intricate in biology. Scientists still don’t fully understand what exactly triggers germination, but several
factors are known:
● Coffee cherries have no “dormancy” period, unlike most other plant seeds, and are ready to germinate at
almost any moment after ripening.
● While still on the coffee tree, cherries do not germinate because the process is suppressed by enzymes
from the parent plant.
● During sun-drying, cherries don’t germinate because moisture content decreases (signaling unfavorable
conditions for sprouting), and structural breakdown in the bean gradually eliminates its ability to
germinate.
● In a water-rich environment, once the bean is pulped, germination starts automatically, as the conditions
are interpreted as favorable.
During germination, any seed rapidly consumes its stored nutrients — beginning with sugars. A coffee bean is
composed of 5%–9% sugars by weight, about 90% of which is sucrose. This means that during the first few days
of wet processing, the tiny sprout (still invisible inside the bean) consumes some of these sugars, which are
responsible for sweetness, along with certain amino acids and other compounds.
Therefore:
● Beans dried naturally or processed semi-dry don’t actually gain sugars from the pulp and mucilage;
● Washed beans, however, lose part of their inherent sugars, reducing sweetness.
This is why the dry method often produces sweeter specialty coffee.
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