Discourse on extraction variables is a rabbit hole that is easy to fall VERY far down unintentionally - it is a topic worthy of lectures not simply a few dot points, but today, for brevity I'll try and condense the most pertinent points into dots.
- The quality of your cup of coffee (extracted either with an espresso machine or 'otherwise' i.e. non-espresso/filter/brewed e.g. french press, pour-over, siphon etc.) is made up of strength (the total of coffee beans in your cup relative to the water in it) and extraction yield (the percentage of the coffee beans you used that made it into said cup - don't worry if that sentence is pretty unintelligible at this point).
- Strength is the measure of the 'volume' of the flavours you perceive in your coffee; you can increase the strength of the coffee by either using more coffee beans to begin with or by extracting more from those coffee beans - strength is completely personal and for the most part can be adjusted independently of extraction yield, which is neat.
- Extraction yield is what determines the particular flavours in your coffee and the balance of those flavours - extract too little from the coffee beans and the coffee may be sour, grassy and/or weak (under-extracted), extract too much from the coffee beans and the coffee may be bitter, savoury or too strong (over-extracted), somewhere in-between lies nirvana.
- To increase (decrease) extraction yield:
- Grind finer (coarser).
- Increase (decrease) brewing water temperature.
- For non-espresso brewing methods:
- Agitate the coffee slurry more (less).
- Steep the coffee longer (shorter). [NB: To a point at least, but that's another post for another day.]
- For percolation methods (including espresso):
- Increase (decrease) the amount of brewing water used relative to coffee grounds used.
Our brewing recipes are thus suggested ranges of these parameters to work within - a base to start with and then tweak to your liking. You will have to fine tune your variables based on many factors, including: brew water mineral content, grinder quality/applicability, number of days since the coffee was roasted (and therefore the amount of carbon dioxide being released by the coffee grounds upon contact with water), calibration of the thermometers used (if any), stirring/pouring action (non-espresso), use or lack of pre-infusion (espresso), and personal taste! You will find your variables change as the coffee ages. You may even find your variables lie outside our suggested range - that's perfectly fine! All that matters is the coffee tastes good to you (or whoever you are serving it to) - our recipes are guidelines not rules.
A few final points:
- Our espresso recipe is based on what we feel is the best expression of the coffee (in regards to flavour clarity and mouthfeel) but you could pull shorter shots at a higher temperature and still get something absolutely delicious if that is more to your personal preference.
- Having pre-infusion enabled on an espresso machine, all else being equal, will require lowering the extraction rate (yield) via other variables.
- When brewing filter coffee, adjusting other variables (including brewing method/vessel) so as to allow for a relatively finer grind will usually result in a more interesting cup of coffee. (If you want to know why feel free to email us!)