Davis Coffee Center Tests Flat vs. Conical Filters

Coffee preparation techniques besides espresso like pourover.
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Marshall

#1: Post by Marshall »

So, over at the U.C. Davis Coffee Center, they did a comprehensive series of tests to determine if there really is a taste difference between "semi-conical" (e.g. Hario V60) and flat-bottomed (e.g. Kalita Wave) filters. Turns out there is. The short version is
[For lighter roast] The flat-bottom basket yielded flavor attributes with more dried fruit, sweet, and floral flavor intensities, while the conical basket yielded more citrus, berry, and sour. Similarly, the basket shape affected the dark roast, with the flat bottom yielding more pronounced chocolate, cocoa, and woody flavors, and the conical yielding much more intense bitterness.
I think this means most people will prefer the flat bottom. Interestingly the grind did not make much difference. There is a thorough discussion of the methodology and results with several interesting diagrams at Flat vs. Cone: Basket Shape is as Important as Grind Size in Drip Brew Coffee.
Marshall
Los Angeles
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another_jim
Team HB

#2: Post by another_jim »

Hi Marshall, thanks for dropping by and posting this.

It appears, from the PCI (overlaying the flavor components onto the PCI space is very sweet), that the cone filter accentuates sour and bitter flavors, to the detriment of sweet and intermediate ones. The simplest explanation is that it underextracts regardless of grind. Do conical filters draw down faster?
Jim Schulman

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Marshall (original poster)

#3: Post by Marshall (original poster) »

I don't know. I use a Kalita filter in a December Dripper set to "1" to intentionally slow down the flow (about 4 minutes) for 20 g of coffee in 300 g of water. This was a Nick Cho recommendation from when he was taping over two of the Kalita holes (before he designed the December Dripper).
Marshall
Los Angeles

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RapidCoffee
Team HB

#4: Post by RapidCoffee »

Marshall wrote:So, over at the U.C. Davis Coffee Center, they did a comprehensive series of tests to determine if there really is a taste difference between "semi-conical" (e.g. Hario V60) and flat-bottomed (e.g. Kalita Wave) filters. Turns out there is. The short version is
I think this means most people will prefer the flat bottom. Interestingly the grind did not make much difference. There is a thorough discussion of the methodology and results with several interesting diagrams at Flat vs. Cone: Basket Shape is as Important as Grind Size in Drip Brew Coffee.
Interesting article, thanks for posting. In addition to the surprising find that grind doesn't make much difference in pourover coffee (!), I'd like to point out the rigorous methodology used in this study. In the first phase alone, 45 participants were recruited for blind taste testing. Each participant performed 7 triangle tests, comparing different combinations of flat vs cone filters, medium vs fine grind, and light vs dark roast. That's 945 cups of brewed coffee, folks!

Good science ain't easy.
John

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yakster
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#5: Post by yakster »

I wonder if they'll discuss this at the Friday talk.

Royal Coffee Lab & Tasting Room
-Chris

LMWDP # 272

Mbb

#6: Post by Mbb »

Tests were comparisons at same water rate, etc. By a machine.
Thats what it measured....a machines coffee. Thats all it measured....difference of a particular machine.

But the thing is, each device gas its own specialized way of using for pourover. By hand.

Its always been known that kalita or such was more forgiving and easier for unskilled to get a decent cup with.

At the same time, a hario cone wins lions share of brewers competitions.

No mention of what coffee, freshness, etc. As many baristas know, different tools lend themselves better or worse to different coffees too.

And grind....definitely nakes a difference for pourover. Without a doubt. . If it didnt for them, it calls everything into question for me.

This study set to determine.....was there a tasteable difference.

It found...yes.

But...people already knew that.

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happycat

#7: Post by happycat »

Thanks for sharing this.

Wild speculation- flat bottom creates immersion effect that reduces how much water is pulling out of grounds

One of the interesting things about this stuff is how much effort is required to be able to state something with some authority... what is proved was "obvious" and what was disproved makes the study "unbelievable"... science is thankless
Mbb wrote:Tests were comparisons at same water rate, etc. By a machine.
Thats what it measured....a machines coffee. Thats all it measured....difference of a particular machine.

But the thing is, each device gas its own specialized way of using for pourover. By hand.

Its always been known that kalita or such was more forgiving and easier for unskilled to get a decent cup with.

At the same time, a hario cone wins lions share of brewers competitions.

No mention of what coffee, freshness, etc. As many baristas know, different tools lend themselves better or worse to different coffees too.

And grind....definitely nakes a difference for pourover. Without a doubt. . If it didnt for them, it calls everything into question for me.

This study set to determine.....was there a tasteable difference.

It found...yes.

But...people already knew that.
The process is meant to determine whether one single decision makes a tastable difference to blind testers. So isolating that variable was essential. "All other things being equal, blind tasters in a controlled tasting environment, can tell the difference in coffee flavour between cone and flat. Cone is fruity. Flat is sweet."

People did not "know" for certain that was the case because of all the other variables you mention yourself... what is truly a tastable difference- in itself- in isolation? The study is meant to shed light on what is real and what is belief.

The points you bring up raise a lot of other questions about the impact of psychology, expectations and culture. Your comment on Kalita being "forgiving" for the unskilled and v60 being a competition winner suggest beliefs about the importance of the person pouring and their skill in making coffee. All those beliefs shape your expectations for equipment and what you taste. For instance, you choose to reject a scientific study with blind tasters because it doesn't match your beliefs about grind size (which has been scientifically shown to be an expected impact of psychology :D ) there is also the trend in coffee towards fruitiness among the trendsetters.. and the fact that v60 is cheaper and more widely distributed than Kalita...those have an impact on results in competitions. And we've seen anecdotal reports that competitions are won on points and the coffee doesn't always taste great.

This study is meant to bypass all that stuff.

This study was funded by Breville, so they are no doubt looking to see how they can use this info to control their brewing and market different equipment. Marketing is the space for all the culture, expectations, hipster moustaches and aprons to make their impact.

What I like is a handy set of heuristics to use. Depending on your coffee you can choose the shape of cone to help. I've been doing that recently, using a v60 to dig for more flavours from Ethiopians. In the past I've used Kalita to sweeten things out.
LMWDP #603

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Marshall (original poster)

#8: Post by Marshall (original poster) »

BTW, there will be two lectures at the Boston Expo next month by Davis researchers, discussing these and other findings.
Marshall
Los Angeles

Mbb

#9: Post by Mbb »

happycat wrote:."

People did not "know" for certain that was the case because of all the other variables you mention yourself... what is truly a tastable difference- in itself- in isolation? The study is meant to shed light on what is real and what is belief.

.
People did know.
Everyone who has ever made the same coffee using different tools they own, knows that each comes out different, and each has a best way to use it. Dialing in time, grind, temperature , method is needed for each.

Just pulse pouring vs continous pouring makes a difference. Grinding with a different grinder makes a difference. I gave my feldgrind to my son, my kinu tasted better. If i need another travel grinder for extended work travel....ill get another kinu and carry the weight. Funny thing is, feldgrind had less fines, i could see that. But no denying it didnt taste as good to me in my pourover setups.

Perhaps im an exception, though i doubt it. I dont think anyone thinks these tools are interchangeable, or expected to be.

My $7 plastic v60 makes waaayyyy better coffee than a $5 plastic melitta cone i have. Why? I dont know. I know it does on coffees i drink. All i care about is how it tastes, because thats all that matters to me. So i go thru trouble to mail order hario filters vs buying melitta at grocery store

namelessone

#10: Post by namelessone »

Interesting reserach but I'm missing lots of details about how the coffee was brewed, what were the extraction yields among others.

There'll be some lectures at https://coffeeexpo.org/lectures so it might be interesting if anyone wants to attend. These are the related ones:
Sensory and Chemical Explorations into Drip Brew Coffee Flavor Over Time
At the UC Davis Coffee Center, we are engaged in comprehensive sensory research using trained panel descriptive analysis to investigate how different parameters related to coffee brewing impact the flavor, and how these can be manipulated to an individual's desired effect. Of these factors, time can be an important variable-in multiple ways-and this talk will highlight two recent projects.

The first investigated the time-evolution of coffee flavor extraction during the brewing process. By dividing a drip brew into eight parts and evaluating the flavor change every 30 seconds, we offer a more detailed picture of observable extraction changes. The second experiment investigated time elapsed post-brew, comparing how quickly perceptible changes occur when coffee is held in a carafe, in order to understand the stability of flavors depending on holding conditions. Both of these studies offer preliminary data that can be immediately useful to the industry in developing and preserving desired flavors in the coffee brewing process.
Drip Coffee Brewing and the Coffee Brewing Control Chart
The process for brewing coffee appears simple: one pours hot water over some coffee grounds, and then drinks the liquid that passes through a filter. This superficial perspective, however, belies a sequence of complicated physical and chemical processes that govern the quality of the resulting beverage. In this lecture, we discuss the origins of the "Coffee Brewing Control Chart" that is widely used to interpret the quality of drip brew coffee. We discuss how several implicit assumptions in the derivation of the chart yield questionable interpretations in current practice. Furthermore, we discuss several unanswered questions regarding drip coffee brewing that are the subject of ongoing sustained research efforts at the UC Davis Coffee Center.
A New Descriptive Terminology For the Brewing Control Chart - How to Maximize the Flavor Potential of Your Brewed Coffee
The original brewing control chart is overlaid with acceptability zones describing cup flavors. However, these terminologies (strong, bitter, weak, over and under-developed) are outdated and their definitions are not standardized in the industry. In this lecture, the newest results from the UC Davis Coffee Center will be presented, which used the WCR Sensory Lexicon in order to elucidate new flavor attributes related to coffees of different strengths and extractions.

The experiment evaluated a single origin coffee roasted to three different development times in order to assess the importance of roast on the flavor at different strengths and extractions. The position of the coffees on the brewing control chart was modified by using a programmable batch brewer. A descriptive analysis panel was used to capture the sensory profile of these coffees. The results presented will be used to update the descriptive zones of the new brewing control chart. Lecture attendees will learn how flavor can be modified through the brewing process, and how the control chart can be used to create different flavors for a specific coffee. Join us for this lecture to learn how to target and adjust the flavor attributes of a coffee and dial in your batch brew.
Not sure if they'll be available online later on.