Yemen Mocha — The Process and Characteristics of Natural Coffee Processing

After coffee cherries are harvested, they undergo a series of complex processing steps before becoming the roasted coffee beans you see. Many people have drunk coffee but have never seen what a coffee cherry actually looks like.

The fruit picked from coffee trees is also called the coffee cherry.

Coffee beans are actually the seeds inside the coffee fruit. Outside the seed are structures such as the exocarp, pulp, pectin, endocarp, and silver skin. The purpose of processing is to remove these outer layers and obtain the coffee seed inside.

Natural Process Method

The natural process is the most ancient coffee bean processing method.

After the coffee fruits are picked one by one from the heavily laden trees, they are spread flat on the ground, waiting for the sun to dry the moisture in the skin and pulp before they are processed.

The sun-drying of coffee beans works the same way. In some regions, a lack of water resources, long sunshine hours, and strong free sunlight make the natural method the most economical way to process harvested beans.

Do Natural Process Coffee Beans Taste Strange?

Early coffee farmers had no concept of quality control and lacked good technique. After the trees bore fruit, regardless of how ripe the beans on the branches were, they pulled them all down (partly, perhaps, because they couldn't bear to discard them), then spread them directly in the yard to dry, turning them when they felt it was about time. They might not notice the spoiled parts, or might be reluctant to throw them away. Poultry and livestock ran around nearby. When the beans seemed dry enough, they were collected and stored in the warehouse. It was a pleasant farm scene, but with that method, keeping good quality every time really came down to luck, and it easily produced strange flavors.

Early natural process beans had many off-flavors, and people often tasted unexpected surprises, so some could not appreciate them, partly because of the imprecision of this processing method.

But times have moved on. Even in remote coffee-producing areas of Africa, farmers receive plenty of feedback and new technical knowledge from their sales channels, so today's natural process is completely different from what it used to be.

How is the Modern Natural Process Method Carried Out?

First, at harvest, experienced pickers select fully ripe coffee cherries by hand. Fully ripe cherries are as tempting as bright red cherries and belong to the berry family, which is why we call them coffee cherries. After collecting the red cherries, farmers screen them, manually removing defective cherries before sending them to the drying yard.

African Raised Beds Natural Process Method

Many regions now use "African raised beds" to dry coffee. The beans are spread on elevated racks for natural processing. The biggest advantage is that it avoids the problems of drying directly on the ground, such as earthy flavors and contaminants. It is also not limited by sloped terrain and can be expanded almost without limit. Workers do not have to bend over constantly, making the job more comfortable and efficient.

When drying coffee, bad weather easily affects the fruit. On nights with heavy humidity the cherries must be brought indoors; if not properly managed, the beans are easily contaminated and moldy, tasting rotten and being harmful to health. During drying it is also important to stir periodically so the upper and lower layers dry evenly and to repeatedly pick out defective beans that are not drying properly. It is truly hard, heavy work.

The Secret to Rich and Delicious Flavor

Drying beans with the natural process costs far less than other methods and saves resources, making it the favorite of many low-rainfall countries.

In natural processing, the whole fruit with skin and pulp is exposed to the sun. Drying time depends on the weather at the time, ranging from two weeks to as long as a month. The beans are dried until moisture drops to about 10-12%, at which point the hardened fruits are collected and the coffee beans can be extracted.

Natural process beans have a yellowish appearance and a fragrant fermented aroma from the pulp and pectin being concentrated into the seeds by the sun. The beans may have slightly broken edges, because when hulling, the machine removes the dried pulp and parchment layer at once, inevitably damaging the beans slightly.

The hard work of natural processing is not in vain. High-quality natural beans have the sugar from fully ripe fruit concentrated drop by drop into the beans by sunlight. The fruit aroma is very rich, the mouthfeel is mellow, sweetness is high, and the acidity is not as sharp as washed beans; the special fermented flavor of natural fruit makes many people fall in love after just a few tastings.

Take FrontStreet Coffee's [Yemen Mocha] as an example. The ancient natural processing gives this bean an ineffable, wild flavor. People who first encounter it may not be accustomed to it, but once they are, they feel what a magical flavor it is; without that wild, ancient character, they would feel something was missing.

FrontStreet Coffee's Recommended Brewing Parameters:

V60 / 90°C / 1:15 / Time two minutes

Flavor notes: grape acidity, spices, cocoa, chocolate

FrontStreet Coffee Recommendation

Natural processing rewards patience, and a few of FrontStreet's beans show just how varied the results can be. FrontStreet's Yirgacheffe Red Cherry is a classic example. Natural processing demands consecutive sunny days, and drying typically runs 27-30 days. Only fully ripe red cherries are used; they are spread on raised drying beds to keep them off the ground and away from insects, dust, and bacteria, and turned at intervals for even drying. Medium-light roasted, it keeps elegant florals and bright acidity while adding clear tropical fruit, a full fermented note, and sweetness.

FrontStreet's Ethiopia Huakui shows what an excellent growing environment plus natural processing can do. High altitude, a superb site, fertile soil, and carefully selected ripe fruit give it a delicate aroma, and the natural process of Sidamo brings out its charm: light fermented notes, florals, citrus, and mango, with a rich, complex body, honey sweetness, cocoa, a touch of spice, and a long finish.

For a different twist, FrontStreet's Colombia Sidra uses a double anaerobic natural process. Before drying, the whole cherries are fermented twice in sealed tanks with carbon dioxide injected to drive out oxygen, creating an oxygen-free environment that slows sugar breakdown and pH decline, giving higher sweetness, more complex flavor, and a dense texture. The cherries are then dried on beds until moisture is reached and hulled. The result is a bold tropical aroma with passion fruit, apricot, dried fruit, and grape, plus an almond-like finish.