Recap

• From a taste and flavour perspective, there is an association of increased bitterness and astringency in over-extracted brewed coffee.

• There is an association with vegetal and sour flavours in under-extracted brewed coffee.

• There are gradients of extraction in every cup owing to the undesirable spread of particle sizes in ground coffee. This means extraction is an average.

• In 1959, the first Brew Control Chart was developed by Earl E. Lockhart and a sensory panel. The 18-22% extraction yield target was established for filter coffee which has continued relevance today.

• Extraction target ranges can be redrawn when the spread of grind size particles is reduced.

• Similarly, when using inferior coffee equipment, results are usually better when you target lower extraction yields.

• When you know any three of the four key brew parameters, of TDS%, Extraction %, Dose, and Beverage Weight, you can use coffee algebra to work out the unknown quantity.

  • Applying these equations helps clarify your understanding of how coffee apps and spreadsheets work.

  • It helps you locate recipe details to make your brewing more accurate.

• We introduced you to a new set of calculators in a toolkit which will help you, not only with the certification process in the course, but will also be something to take home.

New Terms

• Double Hump: a term explaining the marginal gains in coffee flavour when under extracted brews are optimised for ‘surface extraction’, usually involving inferior coffee equipment.

• Sensory Science: a scientific discipline that uses statistics and experimental design to obtain objective quantitative data about organic products.

• Surface Extraction: where the solute is removed from the outsides of coffee grinds through a process of erosion,