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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 published a new method to make coffee concentration measurements precise to 0.01% TDS with a refractometer ! It features convenient steps to take so that you completely remove the issues of evaporation and temperature differences that could easily introduce errors of > 0.05% TDS in your measurements ! You can find out more about this protocol on my blog (link in bio). I also just made my next blog post immediately available to my Patreon followers (link is also in my bio): in that upcoming blog post, I talk about a scientific paper that carried computer simulations of percolation (last image) and I discuss the different variables that I now think affect extraction uniformity. It's not just about channels ! #coffeescience #coffeegeeks #coffeeadastra #coffee #refractometer #specialtycoffee #coffeeexperiment #coffeebrewing
This morning I’m treating myself with @gardellicoffees’ amazing Gesha Village Auction Lot 6. This natural Gesha is so floral it almost feels like drinking perfume (or at least what you’d think drinking perfume feels like haha). It has a nice and complex acidity that reminds me of pineapple and kiwi, but also of peach and lime. The taste ends with a nice, balanced sweetness that almost feels like bubble gum. I brewed this cup with my usual recipe (described on my blog; see link in bio) with Rao/Perger brew water, a 22g dose and 1:17 ratio, which got me a 323g beverage at 1.45% TDS for an avergae extraction yield of 21.3%. This is suprisingly high for a natural processed Gesha. I made some minor tweaks to my V60 recipe recently based on my turbidity measurements; I now pour a bit lower (14 cm above the slurry) with a 3-6 g/s kettle flow, and I prepare the nest shape with my finger rather than a chopstick (see photo). These modifications gave me a marginal ~0.3-0.4% increase in extraction yield but made my brews less astringent and cloudy. #coffeeadastra #coffeegeeks #coffee #pourover #GSC #GardelliSC
This morning I’m drinking a fantastic coffee roasted by @passengercoffee, the Alexis Gonzales washed Colombia varietal, from Colombia ! The tasting notes are incredibly accurate for me; it really has a bright black currant acidity with an intense and lingering sweetness that reminds me of pineapple and litchi. I brewed this one with my usual V60 recipe (see link in bio) with Rao/Perger water, a 22g dose, 1:17 ratio, 45 sec bloom with the EG-1 grinder at 7.0@700 RPM (burrs touch at 1.6) and obtained a 3:17 brew time, 1.46% TDS concentration and 320g beverage, corresponding to an average extraction yield or 21.3%. That photo is featuring @umeshiso_’s beautiful cupping spoon, thanks again ! I use it for stirring my coffee when I’m not cupping, just because it’s nice. #pourover #coffeeadastra #coffee #coffeegeeks #v60
For those of you who understand French, @cafe.normal just released their latest episode where I discuss various topics with Seb for more than an hour, including extraction dynamics, brew water, coffee grinders and more ! See the link in my bio for the episode. I really loved this discussion, and frankly all other episodes of the podcast too ! So much so that I binge-listened to the whole series in two days 😂 Thanks again to both Seb and Elise from @cafe.normal for the opportunity, I loved being a part of this awesome project. #coffeegeeks #podcast #coffeepodcast #coffeegrinder #coffeegrinds #coffeescience #waterforcoffee #coffeeextraction
I just released my latest blog post (link in bio) where I investigate how insulating my kettle affected its temperature stability ! I don't know if this will be as useful for every kettle out there, but the smaller 600 mL kettles like the @mybrewista artisan gooseneck seem to greatly benefit from additional insulation ! This has had a really positive impact on my latest brews' extraction yields and taste. In my next blog post (immediately available on Patreon; see link in bio), I outline a very detailed analysis of the hurdles that prevented me from getting TDS measurements with 0.01% accuracy until now. In it, I also share a detailed methodology for you to overcome these hurdles and easily obtain very accurate TDS measurements. It will become public in a few weeks from now. #coffeeadastra #coffeegeeks #pourover #v60 #refractometer #vst
Don't Bother Covering your V60 ! I recently noticed that some of my brews had channeled because I gently knocked the V60 when try to put on or take off a cork lid I made to maximize slurry insulation. Because it makes the V60 preparation more messy,, I decided to finally make sure that the lid was actually useful. In the graph above (third picture), I show two brews prepared identically, one with the lid and one without. The temperature a few millimeters above the coffee bed (see last two pictures for the temperature probe location) was only different when the slurry went below the temperature probe. So, the lid keeps the air above the slurry warmer, however air conductivity is very low especially in the absence of air movement, and therefore the air temperature doesn't have enough time to really affect the slurry temperature. Both brews had exactly the same average extraction yield: they both had 1.40% TDS with a 22g coffee dose and 325g beverage weight for a 20.7% average extraction yield. This is pretty much the average I get for that coffee (@gardellicoffees’ M'zungu Project), it extracts a bit lower than average. It tastes great at this extraction yield. There's another lesson I took from the two graphs above: I obtained an inconsistent bloom temperature in the two brews, and that has nothing to do with the lid: I was just too impatient and poured when the @mybrewista kettle base said it reached 212F in the "with lid" brew. You actually have to wait a good 20 seconds after that for the kettle to really reach 212F (my next blog post discusses this more). #coffeegeeks #coffeescience #coffeeadastra #pourover
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Website logo by Daniel Demay

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

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Resources

  • Grind Size Application
  • Current V60 Recipe
  • A V60 Pour Over Video
  • Current Siphon Recipe
  • Flavor Wheels
  • Brew Water Crafter Tool
  • Water Recipes Spreadsheet
  • Bottled Water Spreadsheet
  • Coffee Filters Analysis
  • 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 212 other followers

Blog Stats

  • 108,783 hits

Category Cloud

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