Q Grader Tips: Extraction

Continuing on from our blogs on coffee grind size and water quality, this week we lift the lid on coffee extraction...

Coffee Extraction

So, what is extraction?

In definition terms, it’s the percentage by weight of the coffee grounds that have dissolved into the water that makes up your coffee (or put simply, the amount of soluble coffee solids that end up in your cup).

Why is this important? There’s a craft to brewing good coffee, it needs to be of the correct strength and 'balance' to produce the great flavours you deserve.

Let’s go a bit deeper

Three variables create the aroma, taste and body in the coffee cup:

  • Strength - refers to the measure of the concentration of solubles in the beverage, and is usually expressed as a percentage of flavouring material to water. (Think similar to juice concentrates). For example, filter coffee has approx. 1.2% coffee to 98.8% water, whereas espresso has approx. 9.5% coffee to 90.5% water – (i.e  more concentrated).
  • Extraction - or sometimes described as "solubles yield" - refers to the amount of solubles extracted from the coffee beans and, like the strength of coffee, this is also expressed as a percentage. The ideal percentage is 18-22% of the coffee grounds dissolved into liquid.
  • Brewing formula - refers to the ratio of water used per quantity of coffee.(Typically 60g per litre).

What about extraction?

Extraction is important because it impacts the ‘balance’ and flavour of the cup, if you don’t extract enough solubles then you have achieved under-extraction, which delivers a grassy, sour, peanut/bready taste. If you extract too many solubles then you achieve over–extraction which delivers an astringent, bitter taste.

Key factors in Coffee Brewing and Extraction:

  • Particle size – try an espresso grind in a cafetiere and see how bitter it tastes!
  • Particle uniformity – good grinders produce a uniform particle size in the grind, this is very important.
  • Time – brew too quickly and you’ll under extract, brew too slowly and you’ll over extract.

What about strength?

Just as important however, is strength – if you get the concentration wrong, even a well balanced coffee will taste poor. Strength is a measure of soluble concentration (think fruit juice concentrates).

Lets assume we’ve got the extraction correct but get the brewing ratio wrong (by adding too much or too little water, for example). We could end up producing a weak and underdeveloped brew or a strong over concentrated one! Not only that, if you get the brewing ratio wrong it will also affect extraction and the balance of flavours.

Now I’m totally confused…

Brewing great coffee is a craft that can be learned by all, whether it's a champion barista in a café or filter coffee drinker at home; the same essential elements apply.

Once again, here are five essential elements of good coffee brewing that will help produce balanced, flavourful yumminess :

  1. Correct coffee to water ratio – a good rule of thumb is 60g of coffee per litre of water, use some good weighing scales and adjust slightly to your taste! See our 'Water Blog' here for more tips... 
  2. Coffee grind that matches the brewing time  see our previous blog on 'The Perfect Grind' here, an essential to brilliant coffee brewing and mastery of this will bring you great joy…(also ensure your grinder is of good quality).
  3. Proper operation of the brewing method, including:
    • Time of contact for the coffee grounds and water (appropriate grind – extraction!)
    • Temperature of water (don’t use boiling water! – just off the boil 93 degrees).
  4. Using the appropriate brewing method for the coffee (i.e. some espresso blends won’t taste good in a cafetiere).
  5. Good quality water – not too hard or soft, and without chemicals; chlorine, fluoride etc.

How do I know if I’ve brewed correctly?

Good question! Here at YCE we have the luxury of a coffee lab where we can measure grind size, extraction %, strength ratio etc. but for our customers we recommend the following:

  • Stick to our brewing tips above.
  • Develop your palate for tasting coffee (stay tuned for our next blog).
  • Once your palate is more developed  you’ll be instantly able to recognise an under or over extracted coffee, or one with poor balance.
  •  Try our taster pack…

coffee extraction tips

Next Blog : Palate enhancing techniques, the coffee nerds journey….