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https://baristahustle.com/blog/espresso-with-aeropress-filter-papers-above-and-below-the-coffee-bed/

This week, Scott Rao made espresso with filter papers above and below the coffee ...
Barista Hustle - BHLearn / 2019-05-17


 바리스타 허슬의 글인데, 최근 스캇 라오의 에어로프레스 필터를 이용한 커피 추출에 대한 내용이 소개됩니다. 이미 그 내용들을 충분히 다뤘으니 크게 흥미로울 것이 없는데 글 가운데 쓰고 떫은 고분자 물질의 추출에 대한 재미난 설명이 있어 소개해봅니다.


“There’s a law of physics called the no slip boundary condition which means that the velocity of a liquid flowing past a surface is exactly zero at the surface itself. This means that the only way for molecules to escape from the surface is via diffusion, and for large molecules like the bitter tannins this is very slow – a good thing because we don’t want them. The only way for these molecules to escape is to get turbulent flow coming as close as possible to the no slip boundary – and the only way to do this is via the Forcheimer, rather than Darcy flows mentioned in the previous post. Channelling is a sort of Matthew effect – the more flow starts down one path, the more turbulent it gets and the more it flows, creating more turbulence and dragging out more tannins. So anything which reduces channelling will help reduce the bitter extraction.”

In other words, it’s not just over-extraction:  tannins and other large molecules need the turbulent flow created by channels to extract into the coffee. Because our tongues are so sensitive to bitterness and dryness, it doesn’t take much of these molecules to ruin an espresso. However, if we’re able to reduce channeling, then we can push extraction higher before these flavours start to become apparent. “‘Over-extraction’ is an overused term,’ Scott explains. ‘These days I never use the term except to describe localized over-extraction due to channeling.’




댓글 3

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olive731

May 19, 2019 18:04

보유자격 없음

저도 요즘 입자 조절 하면서 드립 내리는데 위 글이 어떤 말인지 이해가 가네요. 윗글에 동감이 많이 되네요.

좋은 정보 감사합니다.^^

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서리 작성자

May 20, 2019 11:37

^^ 참 신경 쓸게 많은게 커피죠. 댓글 감사합니다.

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meeny77

May 23, 2019 10:31

보유자격 없음

좋은 정보 감사합니다




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