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Category: Physics

Posted on January 9, 2019January 30, 2019

Why Spin the Slurry ?

Today I'm excited to release a joint blog post with Scott Rao, the one who helped me so much understand the basics of brewing, and also helped me to improve my cups of coffee significantly. I was never really proud to serve my friends a cup of V60 coffee that I made, and this is …

Continue reading "Why Spin the Slurry ?"

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I just wrote a new blog post (link in bio) about how the differences in extraction mechanics between a percolation and immersion brews will result in different profiles of chemical compounds, even if you use the same coffee beans and prepare a brew at the same average extraction yield ! Suspended colloids and un-dissolved coffee fines play a role too, but they're likely not the only reason why an Aeropress tastes so different from a V60 ! I also just published another new post on Patreon (link also in bio) about the effect of green coffee varietals and processing on coffee flavor, made possible from tasting notes collected on 1,500 coffee bags, a generous contribution of the @firstbloomapp ! This is the next post that will soon make it to my public blog, and it’s my favorite one to date. I added a preview image above; there are dozens more like that one 😍 #specialtycoffee #coffeegeeks #thirdwavecoffee #coffeebrewing #coffeescience #coffeemaths
Thanks so much @lalondeda for that fantastic @rabbitholeroasters decaf coffee from Mexico ! It's so refreshing to see a roaster take good care of their decaf. It really does have notes of spices, milk chocolate and I even get some reed meat flavors ! Perfect for late night shifts. I prepared it with my usual recipe (see my blog for that; link in bio) except a slightly coarser grind size (7.5 at 700 RPM on the EG-1 grinder, rather than my usual 7.0 at 700 RPM; zeroed near 0.0 such that I hear the burrs touching at 1.5 or finer), because decaf coffee shatters more and produces more fines. I used a 1:17 ratio and got a 326 grams beverage with a concentration of 1.29% TDS for an average extraction yield of 19.1%. These low numbers should be expected for any decaf coffee, and I tend to enjoy them at lower TDS too - this is why I started with my default 1:17 ratio even if it's a decaf. My drawdown time was 4:06, just a bit longer than caffeinated, as should be expected. #acaiascale #specialtycoffee #coffeegeeks #brewista #grindsize #coffeegrind #coffeescience #waterforcoffee #particlesizedistribution #raospin #hario #v60 #canadianroastingsociety #vstrefractometer #thirdwavecoffee #coffee-brewing #WeberWorkshops #EG1 #LWW #grinder
I think I'm ready to say that this is the best cup of coffee I've ever tasted. It is the first time I get a bag of the Wush Wush varietal, this one is the Colombian El Zafiro roasted by @gardellicoffees. The tasting notes for this fruit bomb are extremely accurate; it really does taste like cherry, blueberry and kiwi, in an incredibly complex and sweet cup. I brewed this one with my usual recipe (detailed in my blog, link in bio) with the plastic Hario V60, their tabless filters, the @weberworkshops EG-1 grinder with @ssp_grinding ultra-low fines burrs set at 7.0 and 700 RPM (zeroed such that you can hear burrs rub at 1.5). I used the Rao/Perger water recipe (also in my blog) with a 1:17 ratio, and a 22 grams dose for a concentration of 1.47% TDS. I obtained a beverage weight of 324 grams which amounts to an average extraction yield of 21.6%. Today I also tried a totally OCD trick that @mattperger suggested to me; inspect individual beans and remove any unusually pale beans as they slightly damage the cup quality. I only removed two of them, but I don't know yet how much of a difference this made. #acaiascale #specialtycoffee #coffeegeeks #brewista #grindsize #coffeegrind #coffeescience #waterforcoffee #particlesizedistribution #raospin #hario #v60 #canadianroastingsociety #vstrefractometer #thirdwavecoffee #coffee-brewing #WeberWorkshops #EG1 #LWW #grinder #GardelliSC #GSC
EG-1 hack ! Found an acrylic ball that fits in quite well with the design to avoid dust or debris getting in the grinder when it’s not in use. Or, as @awasteofcoffee calls it, I got my own spider protection. #coffeegeek #coffeegrinding #eg1 #lynweber
My repeatability experiment for manual V60 pour overs is now available on my blog (link in bio) ! In this post, I brewed 5 consecutive V60s and determined that my standard deviation in average extraction yield was 0.08 ± 0.02%, not too far from the intrinsic precision of my VST refractometer ! I expected it to be worse that this; this is useful because it means I have enough precision to do some pour over experiments even before I get something to automate them like the Decent ! My next blog post is also already available on my Patreon (and will appear on my blog later). In that one, I discuss the different physics in immersion and percolation brews, and why they lead to very different taste profiles. I also built a small numerical model based on the physics of diffusion to give a clear example of this. #acaiascale #specialtycoffee #coffeegeeks #brewista #grindsize #coffeegrind #coffeescience #waterforcoffee #particlesizedistribution #raospin #hario #v60 #canadianroastingsociety #vstrefractometer #thirdwavecoffee #coffee-brewing #WeberWorkshops #EG1 #LWW #grinder #coffeephysics
It looks like my 35% Buchner extraction from yesterday might have been a mistake ! As some of you have surely heard, the crazy high extraction yields above 30% that @whereisscottrao recently reported were caused by a mis-configured refractometer. As a consequence, my 35% Buchner funnel from yesterday suddenly became 7% higher than any other extraction yield measurement I have heard; @whereisscottrao's highest shot at WOC was in the high 27% in reality, and the highest extraction that @awasteofcoffee ever measured with his Buchner was about 28%. I therefore decided to replicate my result, because such an outlier measured just once does not seem solid ! I replicated almost the exact same experiment, except with a larger dose (17.5 grams) that I measured outside of the Buchner funnel for more precision. I used @regaliacoffee's Karimikui AA Kenyan, which extracts higher than the coffee I used yesterday when prepared as V60 (~22.5% with a 1:17 recipe, compared to ~20.5% for @gardellicoffee's Pena Ramirez which I used yesterday). I still sifted the grounds to avoid clumping, and this time I made a 1:5 bloom that I whisked vigorously in the Matcha bowl, as if I was preparing Matcha tea. I carefully poured it in the upper Buchner, then drained it which resulted in a *much* flatter coffee bed than yesterday. I still used the filter sandwich method, and I used a 1:21 ratio. I'm pretty sure I would not gain anything from a higher ratio because the water dripping down from the coffee bed was very clear at the end. To my surprise, today I obtained a 28.4% extraction yield, much lower than yesterday ! I have three hypotheses as to why that is, in decreasing order of likelihood: (1) I made a mistake when measuring my coffee dose yesterday. (2) Pena Ramirez really extracted higher; could have to do with the lighter roast. (3) I extracted something from my brand new rubber gasket only in my first brew (that sounds horrible).
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Website logo by Daniel Demay

All the better-looking photos on this website are by Noé Aubin-Cadot

Resources

  • Grind Size Application
  • Current V60 Recipe
  • A V60 Pour Over Video
  • Current Siphon Recipe
  • Water Recipes Spreadsheet
  • Bottled Water Spreadsheet
  • Cupping Statistics Widget
  • Extraction yield equations
  • Coffee control chart (percolation)
  • Coffee control chart (immersion)
  • Coffee Glossary by Mitch Hale
  • Specialty Coffee Association Standards
  • Barista Hustle
  • Scott Rao’s Blog
  • Mitch Hale’s blog
  • RSS - Posts

Enter your email address to follow this blog and receive notifications of new posts by email.

Join 132 other followers

Blog Stats

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Announcements Blind Tasting Brew Methods Coffee Grinders Collaborative Posts Cupping Espresso Experiments Extraction Maths Particle Size Distribution Perception of Taste Physics Recipes Siphon Brews Storage and Maintenance Tools V60 Brews Water for Coffee
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