Sifted Chemex with the Kruve Coffee Sifter

A couple weeks ago, I published a video I did in collaboration with my good friend, Jeremiah Harlow. It it, we compared the results of the Kruve coffee sifter in a blind side-by-side taste test. I wanted to make sure we maximized the flavor of each. Turns out, the sifter pretty drastically alters the method of extraction and requires an adjusted recipe from the unsifted counterpart. So I figured I’d take the opportunity to share what I learned about brewing with a sifted Chemex.

Bimodal Brewing

During my research I discovered a phenomenon called bimodal distribution in grind sizes. Bimodal is used particularly in statistics to describe a distribution of data with two separate maximum values represented. In the case of coffee grounds, it basically means the grinder produced a range of grind sizes rather than one single size.

Grinders

All conical burr grinders produce a bi-modal distribution of grounds. As the inner burr rotates within the outer burr, the beans get smashed up either between the peaks or the valleys of the burrs. Even the very best conical burr grinders won’t produce perfectly consistent grounds.

Coffee Beans

Even if the physics of a conical burr grinder allowed for a perfect consistency, roasted coffee beans are predisposed to grinding unevenly. The roasting process makes coffee beans brittle. Like crumbs from a cracker, the crushing force of the grinder produces particles finer than the target grind size.

Affect on Brewing

Without a sieve, like the Kruve, this bimodal distribution of grounds is impossible to eliminate. While fines extract quicker, potentially contributing to over extraction, they also plug up the space between the larger particles, restricting the flow of water. Most brew methods take this into account and use it to their advantage. They allowing the small percentage of fines to restrict the flow and increase contact time with the target sized particles that make up the bulk of the ground coffee.

Sifted Brewing

The Kruve coffee sifter eliminates both the fines and the boulders, narrowing the range to a much narrower grind size. If we were to use the same grind size as the unsifted coffee, water would flow through the ground bed at a higher rate, reducing extraction. So instead, we need to use a finer grind size (two whole steps finer on my Bodum Bistro) to create an optimal flow rate.

Sifted Chemex Recipe

At a Glance

• Ratio - 1:16 coffee to water (42g:672g)
• Water Temp - 203°F
• Grind on Fine, 9.5 on the Bodum Bistro
• Sifter Range: 500 - 1000 micron (bottom sieve - top sieve respectively)
• 45 sec bloom
• Pour in 70-100g stages (6 stages, 98g each)
• Allow to drain
• Brew time: 6-7 minutes

Full Method

Prep

1. Heat your water to 203°F
2. Weigh out your beans
   • Make sure you weigh out enough to compensate for the 40% loss from sifting. For 42g ground, I weighed out 70g of whole bean.
3. Thoroughly rinse your filter and pre-heat the Chemex
   • Place the filter so the three layered side is against the pour spout
   • You want the filter to bond to the glass as closely as possible
4. Grind your coffee on a fine setting
   • Add the ground coffee to the Kruve sifter and sifter for 1 minute
   • Tap the sides occasionally as you sift to knock any grounds loose
   • Carefully pour the rinse water out through the spout
5. Add your sifted coffee to the Chemex
   • Put the Chemex on a scale and tare
   • Add the coffee from the middle compartment of the Kruve
   • Verify the coffee weight and make adjustments as necessary
   • Shake the Chemex to settle the ground bed

Brew

1. Start the timer as your pour the bloom
   • Pour roughly twice the weight of your coffee. For 42g, I poured an 80g bloom
   • Pour slowly, beginning in the center and working your way out
   • Unlike the unsifted method, stir the slurry to ensure an even saturation
   • Allow to bloom for 45 seconds
2. Divide the remainder of your water into 70-100g stages
   • For 672g, I used 6 pours of about 98g each
   • Pour slowly in concentric circles beginning in the center and ending with a pass around the edge to knock down the high and drys.
   • Pause in between your pours to allow the water to drain
3. Allow the water to drain
   • After your final pour allow the water to drain
   • The whole brew process should take 6-7 minutes
4. Remove the filter and serve in a warmed mug

Compare to the Original Chemex recipe

Comparison

In the blind taste test, both Jeremiah and I concluded that the sifted Chemex coffee was smooth, mellow, and incredibly consistent. The unsifted recipe on the other hand produced a vibrant and volatile cup that shifted with almost every sip. I’m assuming this result came from the wider variance in particle sizes. The fines, target grinds, and boulders all contributed a different level of extraction, creating a delicate balance that shifted throughout the cup. The sifted Chemex on the other hand, lacked those varying levels of extraction and produced a singular consistent flavor. You can hear the rest of our thoughts in the taste test videos linked here.

Disclaimer

I did a bunch of research on this topic of bimodal distribution and it’s effect on brewing. However, I don’t have the capability of testing these things scientifically. So, while I’m confident with what I’ve written based on my research, I wouldn’t consider myself an expert. If you have more details on this fascinating aspect of brewing coffee, I’d love to hear from you!

Thanks for reading! If you have any comments, questions or ideas for future content, leave a comment below, shoot me an email, or reach out on Instagram!

As always, Keep Coffee Handsome.

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