Extraction Rate

Extraction rate (also called extraction yield, or EY) is the percentage of the dry coffee dose that is actually dissolved and carried into the finished brew. Not all of coffee's soluble mass is desirable: the earliest compounds to dissolve are fruity acids and bright sugars, while bitter phenolics and harsh tannins extract last. The SCA's Gold Cup standard places the ideal range at 18–22% for brewed coffee — below 18% produces a sour, thin, underdeveloped cup; above 22% introduces harsh bitterness and astringency. Extraction rate is calculated from a TDS reading taken with a refractometer: EY (%) = (brew weight × TDS%) ÷ dry coffee dose × 100.