Extraction Uniformity and Channeling

For a while now I’ve been trying to understand the details of channeling in pour over coffee, and I found it very difficult to find a convincing description of why channeling (and thus astringency) happens suddenly when we grind a bit too fine, even if the surface of the coffee bed looks flat at theContinue reading “Extraction Uniformity and Channeling”

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 roasterContinue reading “The Repeatability of Manual V60 Pour Overs”

An App to Measure your Coffee Grind Size Distribution

[Edit April 20 2021: Chris Satterlee generously developed install packages for both OS X here and Windows here ! His full GitHub repo is here. I’m very thankful for this help (it’s not straightforward at all to do this).] [Edit April 25 2019: Please note this is not an iPhone or Android app, and IContinue reading “An App to Measure your Coffee Grind Size Distribution”

A Recipe to Brew High Extraction Coffee with the Siphon

Today I am finally sharing a recipe for the siphon brewer. I will use a bit of technical jargon at times in this blog post. If you encounter a word you’re not familiar with, I recommend you consult Mitch Hale’s glossary. The siphon method is far from being appropriate for most people’s daily routines, asContinue reading “A Recipe to Brew High Extraction Coffee with the Siphon”

Testing a Model of Extraction Dynamics

In a recent post, I presented a mathematical model for the dynamics of coffee extraction that is based on a few simple hypotheses. One of these is that the rate of extraction decreases exponentially. The rate at which it decreases can depend on many things: the type of coffee, the roast, the amount of agitationContinue reading “Testing a Model of Extraction Dynamics”

A More Accurate Way to Calculate Average Extraction Yield

I recently wrote about the detailed explanations and calculations behind the equations we use to estimate average extraction yield from coffee concentration (often called TDS) measured with refractometers. If you have not seen this discussion, I highly recommend reading it before you start reading this blog post, as it introduces a lot of the conceptsContinue reading “A More Accurate Way to Calculate Average Extraction Yield”

Measuring and Reporting Extraction Yield

Since I received the VST Coffee Lab III refractometer thanks to Vince Fedele’s generosity, I started logging the concentration (in % TDS) of every coffee I brew. This allows you to calculate the average extraction yield of your brew, which represents the fraction of your coffee beans by mass that was dissolved in your brewContinue reading “Measuring and Reporting Extraction Yield”

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”

The Dynamics of Coffee Extraction

[Edit January 30, 2019: After receiving some feedback about this post, I would like to address a few things that I think were not clear enough. I’d like to thank Scott Rao for his comments. First, when I use language such as “over-extraction”, and “under-extraction”, I don’t mean that the associated extraction numbers are necessarilyContinue reading “The Dynamics of Coffee Extraction”