Experiment: Bleached vs. Unbleached Chemex filters

When I started doing pourover coffee at home, I ran into the question of whether to buy bleached or unbleached filters for my V60 and Chemex (and indeed, it’s also a question to consider if you have an automatic drip coffeemaker). I began my manual coffee journey with unbleached filters. Why? Well, it was partly because it was what happened to be available at my World Market location (where I got my Chemex), and also because I was under the impression that unbleached was more natural and somehow more desirable. Back when I baked a lot, I exclusively used unbleached flour because it was considered superior to the bleached stuff – bleaching extended the shelf life of the flour but it also robbed it of nutrients and imparted a slightly metallic taste to the baked goods. I figured that if I cared about flavor, I should get unbleached filters because I wouldn’t want any weird flavors in my coffee.

Fast forward a bit to when I invited some friends over for a tasting of my top coffee of 2015, Square One Coffee Roasters Panama La Esmerelda Gesha, and I served it to my friends both made in a Chemex and in a french press. One of my friends, Bill, commented that he could taste the paper filter in the batch brewed in the Chemex, and this made me start doing some research regarding filters. Well, as it turns out, a common complaint from people is that unbleached filters do impart a stronger “papery” taste than the bleached ones, which taste “cleaner.” Chemex-brand bleached filters involve no bleach at all, and I started buying the “bleached” filters from that point on.

I’ve long wanted to compare the two kinds of filters side-by-side to determine how big, if any, of a flavor difference there is between the two. For this test, I decided I wanted to use one light roasted coffee (PT’s Coffee Ethiopia Gedeo Natural) and one medium-roasted coffee (PT’s Coffee Flying Monkey Blend).

First up, the light roast!

Bleached filter: As you might have seen in my review, the coffee tasted like a toasted Fig Newton with a buttery finish, with a very strong berry aroma. Really delicious.

Unbleached filter: This tasted slightly bitter and I could definitely taste the paper – it reminded me of the brown paper bags I took my lunch to school in as a kid. There was much less fruit flavor in this coffee – it didn’t resemble an African coffee at all anymore. If I was given this coffee and asked to determine the origin from a blind taste-test, I wouldn’t have been able to do it. It just tasted generic – the paper took over everything.

Next, the medium roast.

Bleached filter: Woooo, this came out tasting dark and rather harsh. I actually wrote “Sith” in my notes. This was too much for me – I rather enjoyed the Monkey Blend as espresso but I didn’t like it brewed this way – it was too intense and spiky.

Unbleached filter: Well, this was a bit of a surprise… I did taste the paper but I more smelled and tasted dumplings (Korean mandoo, to be specific). Very odd!!! Besides the unexpected dumpling flavor, I was also surprised that the coffee brewed in the unbleached filter was less bitter than the bleached version – it was like the paper flavor tamed (or perhaps overshadowed?) the spiky notes that I objected to in the bleached version.

Summary: If you enjoy light roasts, definitely get yourself some bleached filters so as not to add any distracting flavors to your coffee. If you enjoy darker roasts, it’s maybe not quite so clear-cut of a decision, but I think I would still opt for a bleached filter over the unbleached. After all, dumplings??

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