What's the Difference Between Washed and Natural Coffee? What Are the White Flakes in Coffee Grounds? Should You Remove Coffee Silver Skin?

White Flakes in Ground Coffee: Should They Be Removed?

"There are many white flakes in the coffee I ground. Should I pick them out?"

Many of us have encountered this situation when grinding coffee beans—when grinding certain coffee beans, the resulting coffee grounds are mixed with numerous white flakes. This is one of the most frequently asked questions received by FrontStreet Coffee's customer service, which has led FrontStreet Coffee to find various ways to "brew" these white flakes each year. Friends who have read the article "Three Key Differences Between Natural and Washed Coffees" will know that these white flakes are actually coffee silverskin—the only substance that remains on coffee beans after processing is complete.

Although the coffee processing removes all substances other than the coffee bean itself, part of the silverskin is enclosed within the coffee bean. Therefore, after processing is complete, this enclosed portion of silverskin remains on the coffee bean.

Why Washed Coffees Have More Visible Silverskin

If you frequently purchase different types of beans to try at home, you've likely noticed that not all coffee beans produce numerous white flakes after grinding. This situation is typically concentrated in washed coffees (more obvious, producing many more flakes). FrontStreet Coffee explained this in detail in the previously linked article, so we'll briefly mention it here. There are two reasons: First, washed coffees retain more silverskin after roasting. During the washing process, the silverskin's integrity is compromised, which means less silverskin falls off during roasting.

Another reason is that washed processing doesn't allow the silverskin to absorb excessive sugar content during processing, whereas other methods like natural and honey processing allow the silverskin to be infused with sugars. The sugar content causes more caramelization reactions in the silverskin during roasting. After roasting, the silverskin becomes almost charred black. Because its color is similar to the coffee bean, people mistakenly believe that beans processed this way have no silverskin. In reality, the silverskin still exists but is overlooked because its color is too similar to the coffee grounds, as shown below:

Does Silverskin Affect Coffee's Taste?

The reason many friends ask the opening question is their concern that silverskin might affect the coffee's "quality." Therefore, FrontStreet Coffee previously collected silverskin that had fallen off during roasting and brewed it separately. Pour-over, pressure, immersion—various extraction methods were attempted. The resulting "silverskin tea" showed consistent characteristics: slightly sweet with red date flavors and a hint of genmaicha (brown rice tea) aroma. If brewed too long, the finish might carry some astringency.

As you can see, silverskin has its own flavor. However, this result only appears when brewing a very large amount of silverskin. The amount of silverskin present in coffee grounds is far less than one-thousandth of what FrontStreet Coffee brewed. This brings us to the question: in this situation, does the presence of silverskin still affect the overall coffee performance?

Testing Silverskin's Impact on Coffee

Excellent! To satisfy everyone's curiosity, FrontStreet Coffee will sift out the silverskin from coffee grounds today and use cupping to see what difference exists between coffee with and without silverskin. The coffee bean used for this test is washed Panama Geisha "Butterfly," which possesses a considerable amount of silverskin due to its washed processing. The method for removing silverskin is simple—just have a colleague pick them out by hand~

Just kidding! Because silverskin is very light, any breeze can blow it away. We only need to use any tool to create a gentle breeze over the coffee grounds to blow out the silverskin. If you're interested and have time to spare, you can try this at home, but remember not to use too much force, or you might blow away the coffee grounds too~ Below is the comparison after completion.

Then we pour 94°C hot water and wait for four minutes.

After time's up, we break the crust, remove the grounds, and begin tasting. The tasting revealed that in terms of flavor, neither cup showed any impact from silverskin—both displayed the Butterfly's characteristic floral aromas, citrus acidity, and green tea notes. However, in terms of cleanliness, the cup with silverskin blown out was slightly cleaner. Other aspects were identical. Without a comparison, you basically couldn't taste the difference.

In conclusion, we can determine that although silverskin has its own flavor, because the silverskin content in roasted coffee beans is minimal, it does not affect the coffee. Unless you're competing in coffee competitions, silverskin can be completely preserved~

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Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473