Distinguishing Natural Yirgacheffe from Washed Yirgacheffe - How Processing Methods Affect Brewing Parameters

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Today's featured coffee is Yirgacheffe. Natural process Yirgacheffe and washed process Yirgacheffe are the most common varieties. Because their processing methods differ, their brewing techniques are also different.

Visual Differences Between Natural and Washed Coffee Beans

Observation from Silver Skin

The washed processing method typically removes the silver skin from coffee beans during processing, presenting a special luster. However, the dry processing method (natural process) only removes the coffee husk, leaving the silver skin completely intact.

Green Bean Differences

Generally, washed green beans are blue-green in color, while natural processed green beans are yellow-green.

When we roast and heat coffee beans, dry processed beans will shed much more silver skin, while washed processed beans shed considerably less.

When examining the center crease of roasted coffee beans, if quite a bit of white silver skin remains, it's more likely to be washed processed coffee beans.

Silver Skin (Chaff)

Inside the parchment layer, there is an even thinner membrane wrapping the coffee bean. Due to its lustrous, silver-tinged color, people habitually call it "silver skin."

This layer of silver skin will fall off during roasting. Usually, when you grind coffee, you might notice some silver fragments in the coffee powder. These fragments are precisely the silver skin that failed to separate from the beans during roasting.

Roasted Beans

Washed Yirgacheffe has more silver skin, while natural Yirgacheffe has less silver skin.

Natural processed beans have relatively more external silver skin, which comes off more thoroughly during roasting, so there's relatively less when grinding. Washed beans have more internal silver skin, which leaves considerable residue after roasting, appearing more during grinding. Of course, this is directly related to the roast degree - the darker the roast, the cleaner the silver skin removal.

Excessive silver skin can cause astringency, but if green beans are over-processed to remove silver skin, it can lead to reduced flavor.

Moreover, the center crease of washed beans definitely contains silver skin, but the issue is that this part may not necessarily produce obvious astringency, so don't completely pick out all the silver skin.

Differences in Dry Aroma

Natural Process Yirgacheffe: Light fermented wine aroma, spicy fragrance

Washed Process Yirgacheffe: Jasmine floral aroma, lemon or lime acidic fragrance

Brewing Parameters Reference

Referencing FrontStreet Coffee's pour-over parameters, water temperature and grind size have slight differences:

Natural Process Yirgacheffe Red Cherry: Recommended to use 15g of coffee with 89°C water temperature, Fuji grinder setting 4, V60 dripper, 1:15 coffee-to-water ratio. First pour 30g water, bloom for 30s. Second pour to 104g water then pause. Continue pouring to 225g total water. Don't use the final tail water. Extraction time around 2:02s.

Washed Process Yirgacheffe Kochere: Recommended to use 15g of coffee with 92°C water temperature, Fuji grinder setting 3.5, V60 dripper, 1:14 coffee-to-water ratio. First pour 30g water, bloom for 30s. Second pour to 110g water then pause. Continue pouring to 215g total water. Don't use the final tail water. Extraction time around 2:05s.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473