Advanced Coffee Making

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The Extracted Mass

ACM 1.09 – Recap and Glossary


  • The extracted mass can be segregated into thirds: bitter, sour, and sweet.

  • Fermentation plays a large part in the production of the sour/acidic elements in green coffee.

  • We can calculate the extracted mass with dehydration ovens or refractometers.

  • The coffee industry uses refractometers because they’re cheaper and they give instant readings.

  • Extraction yield measurements are averages — we calculate them to see how the measurements change in response to our roasting and brewing decisions, e.g. changes in grind or temperature.

  • The extremely complex chemical makeup of coffee creates complexities in refractometry that can be resolved with temperature correction calibrations.

  • This process involves taking a highly accurate dehydration sample and then comparing this sample to RI readings taken at a range of temperatures. This process makes the coffee refractometer accurate to within +- 0.02%TDS.

  • We emphasise the importance of pairing your sensory skills with refractometry.

New Terms

  • Acidity: the level of perceived sourness and/or fruitiness.

  • Agronomist: an expert in the scientific study of soil and plant management.

  • Aliphatic Acids: the acids of non-aromatic hydrocarbons. In coffee, they are created through the break down of sucrose, fructose and glucose. Of these, the principal in coffee is acetic acid (vinegar).

  • Caramelisation: a type of non-enzymatic browning of sugar that is brought about by thermal decomposition.

  • Degradation

  • Disaccharides: aka a double sugar, are a class of sugars formed when two monosaccharides are bonded by glycosidic linkage (a type of covalent bond specific to carbohydrates) Sucrose is a disaccharide.

  • Dispersion (optics): when different colours of light refract at different angles — think ‘Dark Side of The Moon’ album cover.

  • Fermentation: the chemical breakdown of a substance caused by the enzymatic action of yeasts, bacteria and microorganisms.