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Gold extraction: scientific interpretation of Coffee extraction terms
Blonding: describes the conversion of the liquid from dark brown with tiger stripes to uniform light yellow. This usually occurs in the last 1amp 3 stage, indicating that the extraction operation can be ended. The over-yellowing part of espresso has a light taste and almost no aroma. If it lasts too long, it will dilute the mellowness and is no longer a pleasant taste.
Insufficient extraction: coffee solids are not extracted enough to produce a light, boring aroma. Visually, it is a fast and large-capacity extraction, and the coffee oil is a uniform light yellow.
Channel effect (channeling): water flows rapidly through cracks in coffee cakes, resulting in thin, underextracted espresso. When this happens, a yellowing stripe is often seen in the coffee stream; sometimes the channel effect leaves a pencil lead-sized hole in the coffee cake.
Coffee oil (Crema): make sure that espresso makes the right signal (on coffee machines where coffee oil is not forced to produce) and that various gases-air and carbon dioxide-are distributed in water under high pressure. The liquid also includes emulsified oil. A deep golden brown foam is formed on the surface of espresso.
Gold extraction rate (Golden rule): a common term describing the ideal time and capacity for extracting espresso. The Italian National Coffee Institute provides a practical definition of the ideal espresso characteristics, although these parameters are more like the "golden rule". The simple definition is: use about 18-20 grams of coffee to produce 60 milliliters of double espresso in 22 to 27 seconds (from the time the coffee liquid flows out).
Over-extraction: too much coffee solids are extracted to produce a strong, irritating aroma. Visually, the capacity of coffee is insufficient, and coffee oil is a thin layer of blackening. The dark black circle on the edge of the cup is another typical indication of over-extraction or excessive extraction of water temperature.
