Brew variables series – Talk 1 & 2: Extraction and ABCD

The first video introducing our Brew variables talk went live already. Watch the video to see what we plan to cover in the series.

Intro to Talk

If video does not play, click: YouTube: Talk 1 Brew Variables

Talk 2: Extraction and ABCD

If video does not play, click: YouTube: Talk 2 Extraction and ABCD

Summary of what is covered in the video follows


  • To use, you need to understand


  • No matter how you set grind = boulder and fines
  • Way more fines than boulders, and lots of particles in the desired range
  • Tools to sieve exist
  • Some believe the resultant combination give coffee its uniqueness
  • Important to remember this when brewing

Effect on Soluble Extraction

  • Water moves from the outside of the grind to the inside
  • As the water moves, it extracts soluble material of the grind
  • The longer the grind is exposed to water, the more soluble material is available to the final solution or brew
  • As boulders are larger, they will give up their goodness slower than fines will over-extract if overexposed
  • Several studies have found for pressure brews, all soluble material makes it to the final cup within 60 seconds (including over-extracted elements). Will filter, boil or steep brewing it takes 3-6 minutes depending on the grind setting
  • Pressure = espresso, mocha and even vacuum flask
  • Filter/boil/steep = plunger, pour-over, Turkish etc.

How this affects ABCD

  • Since acidity extracts first under extraction is characterised by acidic brews that have little body and sweetness. 
  • Over extracted brew can be bitter and thin
  • So the brew you make need to match your preference for the balance of acidity, sweetness, body and flavours you like without thinning them down or the brew becoming bitter.
  • Only you know what you like hence only you can determine your optimal brew that matches the balance you want, with your equipment

Notes about Acidity and Bitterness

  •  Acidity and Bitterness are often confused.
  • There are over 30 organic acids in coffee and almost as many inorganic acids
  • When coffee people talk acidity it normally means the brighter acids, like Malik, citric, acetic and others. If a coffee is well extracted, then the brighter acids will assist the mouth (and olfactory senses) in identifying sweetness. If there is an under extraction this the sweetness in the coffee is not there causing a sour taste
  • Bitterness is also caused by acids. Both organic and inorganic. Quinine is very bitter (it is used in malaria pills) but once again if you get the extraction correct you will get the classic nut, cocoa and chocolate flavours, rather than the burnt charcoal or chemical taste.
  • One person’s cocoa is another person’s charcoal

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