Perfecting your coffee extraction
The perfect extraction - all caffeine (including decaf) lovers persistently chase the ‘sweet spot’ from their desired origin, or blend, of choice. As coffee has grown to be one of the most popular beverages in the world, so has the number of brewing and extraction methods for this much-loved drink. How we brew our coffee often depends on geographic, cultural and social context in addition to specific personal preference. Understanding coffee extraction will provide a framework as we work to improve the quality of our cup. Learning how to control the sweet, sour and acidity in your brew assists with providing balance in your cup.
The art of extraction can be simply defined as the process that pulls flavours and aromas from coffee using water as a solvent. As we brew coffee, unique compounds are unlocked from the grounds into water, comprising your daily cup.
The final yield typically contains the water-soluble compounds such as caffeine, sugars, acids, carbohydrates and lipids. How the compounds are extracted directly influence the aroma and flavour of the coffee.
The taste test
As we pass water through coffee grounds, not all the compounds are extracted simultaneously. The acidic and fruit characteristics are first extracted. The median sector of the brew contains the sweetness and balance and then followed by bitterness.
If the brew is under extracted, the coffee will lack the sweetness and adopt a sour taste. Contrastingly, an over extracted brew will have its sweetness and acidity overpowered by bitterness. The answer to creating balance is control through several variables.
Does perfection exist?
Yes – is the simple answer. Coffee has an ideal extraction level illustrated by Total Dissolved Solids (TDS). TDS is how many of the compounds have been extracted from the coffee into water. The ‘sweet spot’ is typically 18-22%. In true fashion, stats do not lie!
It’s all about control
Perfection from your coffee requires control and understanding why the final yield does not taste as desired. There are several factors which need to be considered in order to mitigate a sour or bitter cup. Roast type, grind size, brew method, water temperature and extraction time are the fundamental variables which must be manipulated to produce a perfect extraction.
The porosity of a coffee bean becomes determined by the roaster, in turn, directly affecting how grounds become soluble with water. Roast levels are typically divided as light, medium and dark. All the coffee at Big Dog is initially profiled to medium with the aim to emphasise the flavour characteristics of the coffee. The amount of heat coffee is exposed to during a roast determines the porosity and solubility of the bean. Medium to dark roasted coffee is best utlised as espresso due to the decreased extraction time. Contrastingly, less porous, light roasted coffee are often subjected to a filter. First consider the roast profile, then manipulate the variables below as you work towards the perfect extraction.
One of the most common and discussed variables when it comes to coffee extraction. If we’re talking espresso, the grind size and the dose (amount of ground coffee in the portafilter), are the two key components which are manipulated to attain a balanced espresso. This process has a name, we call it “dialing in”.
Espresso requires finely ground coffee in comparison to other brewing methods such as pour overs or French press, which warrant a coarser grind. This may dispel a common misconception for some, despite the ‘strong’ cup profile of espresso, the brew method does not determine the strength. Coffee strength boils down to the grind size.
A fine grind increases the surface area of the coffee, increasing the amount of contact it has with water during extraction. Increased contact results in greater levels of extraction. If coffee is ground to fine, and no other variables are manipulated, the final yield will contain a higher concentration of compounds. This results in a brew with a higher TDS which is subsequently stronger.
If coffee is ground too fine, the final yield will be over extracted, regardless of the brew method. However, grinding coffee finer would generally result in more compounds being extracted from the coffee. The overriding issue here, the grounds will be too fine to allow water to pass through the filter.
Perfecting your temperature
Not focusing on water temperature as you extract coffee is like buying a Lamborghini and fueling it with Diesel, water matters.
If water is under or over heated, the grounds are unable to express the full capacity of their flavour. To pair your specific grind, water must be heated between 92-96 Celsius. Brewing too hot results in the coffee being over extracted, providing a bitter, unpleasant taste, in the mouth. Avoid boiling your water to save yourself from over extracted coffee.
Colder temperatures simply do the opposite and slow the extraction down. If the temperature’s too cold, the flavour and aroma of the coffee grounds aren’t adequately extracted – under extraction, sour taste.
The coffee brewing journey is one of much trail and error, to find out the ‘sweet spot’ of any chosen coffee and brew method. The flavour notes, aromas and mouthfeels are all specific to you, we hope this information helps as you look to perfect your brew.