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 lots of white flakes in the coffee I grind. Should I pick them out?"

Many of us have run into this when grinding beans: certain coffees come out of the grinder with a scattering of white flakes mixed in. This is one of the questions FrontStreet Coffee's customer service fields most often, which has led FrontStreet Coffee to come up with various ways to "brew" those flakes each year. Readers of the article "Three Key Differences Between Natural and Washed Coffees" will know that these white flakes are coffee silverskin - the only substance that remains on the bean after processing is complete.

Although processing removes everything but the bean itself, part of the silverskin stays enclosed inside the bean. After processing is finished, this enclosed portion remains on the bean.

Why Washed Coffees Have More Visible Silverskin

If you frequently buy different types of beans to try at home, you've likely noticed that not every coffee produces a lot of white flakes after grinding. The situation tends to concentrate in washed coffees, which are both more obvious and produce many more flakes. FrontStreet Coffee explained this in detail in the linked article, so we'll touch on it briefly. There are two reasons. First, washed coffees retain more silverskin after roasting. During washing, the silverskin's integrity is compromised, which means less of it falls off during roasting.

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

Does Silverskin Affect Coffee's Taste?

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

As you can see, silverskin has its own flavor. But that result only shows up when brewing a very large amount of it. The amount of silverskin present in coffee grounds is far less than one-thousandth of what FrontStreet Coffee brewed. Which brings us to the question: in that 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 sifted the silverskin out of coffee grounds and used cupping to see what difference there is between coffee with and without it. The bean used for this test is washed Panama Geisha "Butterfly," which carries a considerable amount of silverskin because of 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 blows it away. We only need to use any tool to create a gentle breeze over the grounds and blow the silverskin out. 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 the grounds away too. Below is the comparison after finishing.

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

When time's up, we break the crust, remove the grounds, and begin tasting. 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. In terms of cleanliness, though, the cup with the silverskin blown out was slightly cleaner. Other aspects were identical. Without a comparison, you basically couldn't taste the difference.

In conclusion, we can say that although silverskin has its own flavor, the amount present in roasted coffee beans is minimal, so it does not affect the coffee. Unless you're competing in a coffee competition, the silverskin can be left entirely as it is.

FrontStreet Coffee Recommendation

Since washed coffee is where that silverskin shows up most, it's worth tasting what the process actually delivers. FrontStreet Coffee's Ethiopia Yirgacheffe Gudingding, from the Gudingding cooperative, is a good example: the washed method draws out jasmine florals and a bright citrus acidity to the fullest, and after a light-medium roast it gives off green tea and honey notes. It is a clean, elegant washed cup that works as pour-over, cold brew, or espresso.

For the clearest illustration of what washing can do, take FrontStreet Coffee's Kenya Cherry Tomato. Kenya is especially adept at double-washing green beans, and the repeated soaking and rinsing push the juice-like quality as far as it will go. Expect cherry tomato, smoked plum, pear, black plum, and brown sugar in a sweet-and-sour, juicy cup - which is why it is a favorite among drinkers who love bright, complex washed coffees.