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A Scientific Approach to Coffee Brewing

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Category: Experiments

Posted on September 6, 2019September 6, 2019

An Investigation of Kettle Temperature Stability

In this post I investigate the stability of my Brewista kettle with the Brewcoat insulation and an additional layer of aerogel.

Posted on June 11, 2019September 2, 2019

The Repeatability of Manual V60 Pour Overs

Today I decided to measure how repeatable and consistent my manual V60 pour overs are. My expectations were very low, given how variable an average extraction yield I often get when I brew the same coffee a few days apart. To do this, I used some older coffee I had left from a local roaster …

Continue reading "The Repeatability of Manual V60 Pour Overs"

Posted on February 12, 2019February 12, 2019

Measuring the Concentration of Espresso Shots

If you are wondering why it is widely recommended to use syringe filters when you measure the concentration of espresso shots with a refractometer, or how bad exactly a measurement would be if you don't use such a filter, I highly recommend this recent blog post by my friend Mitch Hale. And while you're there, …

Continue reading "Measuring the Concentration of Espresso Shots"

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  • Grind Size Application
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  • A V60 Pour Over Video
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  • Scott Rao’s Blog
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I just publicly released my blog post about astringency (link in bio) ! It includes a description of what it feels like, the underlying chemistry and what can cause it when we brew coffee. I'm hoping that improving our understanding of astringency will help us avoid it. The next blog post is already available on Patreon (link in bio), where I show the results of a short experiment about the surface hardness of six different green coffees and how they differ more than their mass densities. Maybe the hardness of green coffee could help roasters predict how expensive batches of coffee will behave during roasting ! #coffee #coffeescience #coffeeadastra #coffeegeeks #coffeeroasting #greencoffee
First snow of the year with a delicious coffee by @gardellicoffees, the Alemu Bukato natural Ethiopian. It’s a truly delicious, sweet coffee with plenty of ripe fruit notes. As typical of many Ethiopians, it generates a lot of fines so it’s a bit harder to prevent clogging ! This is my first brew of it, so I prepared it with my usual recipe at 1:17, 22g dose in a plastic V60 and Hario tabless filters, Rao/Perger water at 212F, poured at 5 g/s from about 8-9 cm from the top of the V60-02 wall. My grind size was 7.0@700 RPM on the @weberworkshops EG-1, and I got a drawdown time of 3:40, a beverage weight of 314 grams and a concentration of 1.43% TDS, for an average extraction yield of 20.5%. Next brew I’ll try going a tad coarser because my brew started clogging near the end. #coffee #pourover #coffeegeeks #coffeeadastra #GardelliSC #GSC
Today I’m drinking @timwendelboe’s Fahem washed Ethiopian 74110 & 74148 varietal. It’s a really unique rich and complex coffee that I very much enjoy ! Tasting rhubarb in coffee is kind of weird, but I somehow love it. I also really like being able to see varietals on these Ethiopian coffees ! It’s also one of the most soluble coffees I have ever seen, even more than the Tatmara natural 74112 and 74110. I’m starting to suspect @timwendelboe is onto something maybe with good farming practices ! I brewed it at 1:17, with my usual recipe (see blog for details, link in bio) 22g coffee, 319g out, 1.58% TDS (!) for an average extraction yield of 22.9% and a brew time of 3:40. I used Rao/Perger water at 212F in a plastic V60, the Hario tabless filters, I poured at a fixed ~12 cm from the initial dry coffee bed with a kettle flow rate of 4-6 g/s. I had no signs of filter clogging or astringency even when it cooled, so I might try using more water next time to get a more reasonable concentration 😆 #coffee #coffeegeeks #coffeeadastra #pourover
Stop using oxygen absorber packs with coffee ! I previously recommended using oxy-sorbs to keep coffee fresh in addition to other methods like vacuum sealing and freezing, but I recently realized they can hurt coffee quite badly. It took me a while to realize it because it happens faster with some coffees and not others, and it takes a very long time for it to happen in the freezer (that’s not too surprising). For more than a month now I have had issues with my coffee tasting weirdly harsh after storage, and I was struggling to identify the issue until Matt Perger told me about a suspicion they have at Barista Hustle that oxy-sorbs may interact chemically with coffee aromas. You’ll see some more in-depth blog posts coming out about this soon, but I immediately wanted to stop recommending their use with coffee. I found that it can result in a harsh and metallic taste, less sweetness and less volatile aromas in the coffee. It also doesn’t seem to affect the acidity profile much. It’s a defect that is very distinct from roast, brew and green defects once you learn to identify it. Matt found that 100% of bags in which he used them ended up losing significant aromatics. In the first image above, I show the contents of a brand new oxy-sorb pack. In the second one, I show the contents of a similar pack after two weeks of being vacuum sealed with 80 grams of coffee at room temperature; there is no way enough oxygen was present to react almost the whole pack, as they are rated to absorb most oxygen from a liter of air. It’s pretty clear they react with CO2 (that’s a known fact) but I suspect they may also react with coffee volatiles, while also imparting a bad taste on the beans. Even worse, some packs include moisture to allow oxidation of the oxy-sorb iron and remove oxygen from the food, but moisture is extremely bad for enclosed coffee. I couldn’t find out whether oxy-sorbs have a moisturizer in them. #coffeegeeks #coffee #coffeescience #v60 #coffeeadastra
I’m excited to start reading this book ! Thanks @christopherferan or the suggestion ! #coffee #coffeegeeks #coffeescience #coffeeadastra
I just publicly released my blog post on all the variables that affect coffee brew time (link in bio) ! In it you will find an in-depth discussion of why brew time is such a poor tool to communicate recipes or grind size, and how it's only a useful diagnostic if you are extremely diligent in keeping all the variables fixed in your brewing. I also just made my next blog post available on Patreon (link also in bio): it's a discussion of the mechanisms that cause astringency in coffee, and what astringency feels like. I also discuss ideas for measuring astringency, and how we might want to learn a few tricks from the beer and wine sectors for reducing astringency in our brews. 
#coffeescience #coffeegeeks #coffeebrewing #v60 #coffee #pourover #coffeeadastra
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Credits

Website logo by Daniel Demay

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

Most Amazon links on this website are "affiliate", which means I get a small commission if you buy through them, at no cost to you.

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 258 other followers

Blog Stats

  • 138,764 hits

Category Cloud

Announcements Blind Tasting Brew Methods Brew Temperature Chemistry 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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