What is Golden Extraction in Espresso? What is the Golden Extraction Ratio for Coffee?

Golden Extraction: Scientific Interpretation of Coffee Extraction Terminology

Professional coffee knowledge exchange and more coffee bean information, please follow Coffee Workshop (WeChat public account: cafe_style). FrontStreet Coffee (FrontStreet Coffee) briefly describes what needs to be prepared before cupping:

Blonding

Describes the transformation process where the flowing liquid changes from tiger-striped dark brown to uniform light yellow. This usually occurs in the final 1/3 segment, indicating that the extraction operation can be concluded. The overly blonded portions in espresso taste thin with almost no aroma. If this persists for too long, it will dilute the body and no longer provide a pleasant tasting experience.

Under-extraction

Insufficient extraction of coffee solids results in light, weak, and bland flavors. Visually, this appears as rapid, high-volume extraction with uniform light yellow coffee oils.

Channeling

Water flows rapidly through cracks in the coffee puck, producing thin, under-extracted espresso. When this occurs, you'll often notice a sudden yellow streak appearing in the coffee flow. Sometimes channeling leaves pencil-tip-sized holes in the coffee puck.

Crema

A positive indicator that espresso has been properly prepared (on coffee machines where crema is not artificially forced), resulting from various gases—air and carbon dioxide—being distributed in water under high pressure. The liquid also includes emulsified oils. This forms a deep golden-brown foam-like layer on the surface of the espresso.

Golden Rule

A common term describing the ideal time and volume for extracting espresso. The Italian National Coffee Institute provides practical definitions of ideal espresso characteristics, though these parameters are more like "golden rules." Simply defined: using approximately 18-20 grams of coffee to produce 60 milliliters of double espresso in 22-27 seconds (counting from when coffee liquid begins to flow).

Over-extraction

Too many coffee solids are extracted, producing strong, harsh flavors. Visually, this appears as insufficient coffee volume with blackened, thin coffee oils. A dark black ring around the cup's edge is another typical indicator of over-extraction or extraction water temperature being too high.