The Perfect Brew: Coffee Extraction and TDS

coffee extraction

Coffee extraction requires ground coffee to be immersed in water. This allows the solubles to dissolve and release flavour. Temperature, time, pressure, grind size, the amount of coffee and, its quality all play a vital role in creating the perfect balanced coffee.

Coffee compounds are responsible for giving coffee its flavour. Acids and caffeine are the easiest to dissolve, giving coffee it's light and fruity notes. Lipids and fats, and melanoidins give nutty, vanilla and chocolatey notes. Carbohydrates and fibre provide coffee with its sweet and earthy flavour.

The strength of coffee can be measured by the total dissolved solids (TDS) in a solution. A higher number of solids indicates a more concentrated and flavourful one. A higher coffee to water ratio, hotter temperature and finer coffee grounds can increase the amount of TDS. When the surface area is increased of coffee, it becomes easier for the water to draw out its flavours and aromas. The equation below explains how coffee extraction can be calculated.


Refractometers can be used by roasters or as a valuable parameter for coffee houses and baristas who wish to create the perfect balanced brew. A refractometer measures the angle of light refracted through a liquid to determine its concentration of coffee solubles (the amount of coffee in the finished cup) and extraction yield.

Under Extraction
Under extraction can be caused by too many coffee grounds and lack of water, making the solution over-saturated. It can also be because of too cool temperatures. This can result in a bitter and dry mouthfeel.

Balanced Extraction
Different coffee beans can require different extraction methods. As Arabica grows at high altitudes, it is a thicker and less soluble bean than the Robusta variety, requiring more grams of coffee for a balanced extraction. An ideal extraction will provide complexity with a balanced acidity and a smooth finish. It should be pleasantly aromatic.

Over Extraction
As time progresses, the rate of extraction slows down, as the water becomes more saturated. Over extracted coffee will impart bitter and dry flavours with a short finish. The Speciality Coffee Association of America (SCAA) suggests a ratio of 1:18, recommending 55 grams of coffee for 100ml of water. However, this is greatly dependant on personal taste, the type of coffee and the brewing method.

Our Capabilities
Our extracts and concentrates are able to offer a range of profiles which can be obtained from the same bean. We have low and high brix extraction and concentration capabilities. To find out how we can work with you, please email