What are the 'Immersion' and 'Filtration' devices in the most common coffee extraction methods?

Professional coffee knowledge exchange. For more coffee bean information, please follow Coffee Workshop (WeChat public account: cafe_style).

FrontStreet Coffee discusses that among the most common coffee extraction methods, all approaches fall into two categories: "immersion" and "filtration."

The former is more similar to tea brewing methods, where coffee grounds and hot water are placed in a container, ensuring appropriate time and temperature and stopping at the right moment. "Filtration" allows hot water to pass freely through the coffee grounds.

Equipment inclined toward "immersion" includes: French press, Clever Dripper, cold brew, siphon pot, and Turkish pot;

Equipment inclined toward "filtration" includes: common pour-over filter cups, flannel filters, all espresso machines, and ice drip pots;

This is mentioned as "inclined toward" because even within one extraction method, situations exist where "immersion" and "filtration" work simultaneously. For example, pour-over methods using fine grinding with stirring allow hot water to remain in the filter for a period of time. Meanwhile, the Turkish pot is more of a purely "immersion" device.

Next, let's explore brewing methods

First is gravity. Coffee extraction through gravity results in moderate "diffusion" and very low "erosion" during the extraction process, such as Chemex, Hario V60, and other pour-over equipment. Gravity can make coffee flavors more refined with higher acidity.

When using the above equipment, it's essential to maintain water temperature between 93-96°C to ensure the diffusion rate remains at a level sufficient to extract soluble substances from coffee, especially acidic compounds. This is particularly important for pour-over coffee because acidity enhances flavor complexity and purity.

Second is pressure. For example, AeroPress and moka pot. Coffee extraction through pressure results in high "erosion" and moderately low "diffusion" during the extraction process. Pressure can make coffee texture richer and more full-bodied.

Due to the increased "diffusion" rate, more soluble substances and fibers from the coffee will be extracted. Because of the higher rate, coffee extraction time needs to be adjusted accordingly. Additionally, the type of filtration device will greatly affect the final taste of the coffee.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473