Recap

• The coffee refractometer needs to be cleaned and calibrated regularly.

• Samples must be managed in a way that prevents water evaporating but also allows them to cool to room temperature when reading will be more accurate.

• CO2 content is expected to be higher in dark roast coffees, while H2O content is expected to be lower in dark roast coffees.

  • The effect of these two presences in roasted coffee is to increase extraction yield values.

  • Scientific literature reports a 1.3-2.3% H2O content in low temperature, slow roasts (specialty).

• When calculating extraction yield, the mass extracted from the coffee grinds will reduce the liquid retained.

New Words

• Cellulose Matrix: the honeycomb-like arrangement of cellulose cell walls which in roasted coffee grinds is ripped open and made microporous.