Thread: Analysing naked portafilter shots

hey buschy
heres an article from home barista that you may find helpful

http://www.home-barista.com/naked-extraction.html

aaron

I have to disagree with that article.

Im totally against tiger striping. To me it shows the shot is channeling or many other problems. If you taste the white tiger stripes and the dark tiger stripes, Im sure you will find the while stripes bitter and the dark stripes full of flavor. The photo given looks under extracted giving off Tiger stripes.

It actually says in the article to avoid the blond coffee extraction (under extraction), yet gives permission to it in the photo and in the "tiger striping" comment. Interesting.....

Therefor I suggest you go for an even color and get as much dark and rich coffee from the shot as possible.

If you can extract an even color, it shows the shot is moving evenly through the PF (fully extracting). It also allows you to see the where you are channeling and allows you to compensate on your next shot.

Always check your biscuit, it will tell you all you need to know if you know what to look for. (dose, tamp, even pressure etc)

Go for a grind that allows those 3 drips in around 7 secs, 2 drips in around 15 secs and by the time the 2 drips join you should notice the color lightning signaling the end of the shot around 24 secs.

Originally Posted by 6F435A724D554750220 link=1231241066/2#2 date=1231940720

Im totally against tiger striping.

I guess it would depend whether your shot is a blend or a SO. For a blend Id expect different colours, and hence tiger striping.

Grant

Isnt the white part of the pour/tiger striping forming the crema?

Originally Posted by 2D0118300F170512600 link=1231241066/2#2 date=1231940720

Im totally against tiger striping. To me it shows the shot is channeling or many other problems.

Im afraid I have to disagree with you. If SO beans were entirely uniform in size and density throughout, and the roasting process treated each bean exactly the same, you might stand a chance of having homogeneous colouring but in reality the variation in bean and roasting can be expected to produce variation in the extraction even from well ground coffee.

A point worth mentioning is that tiger striping is far more obvious with a naked portafilter because the stream is not being blended as it passes through a spout.

The key thing to avoid is blonding which makes the extraction thin and bitter.

from the home barista article

dan kehn: "Tiger striping and mottling are leading visual indicators of a good extraction. Tiger striping is formed by the contrast of darker and lighter crema in the espresso stream; ideally it begins early in the pour and is sustained through the end. Mottling is the in-cup confirmation of a good extraction; it is the darker brown speckling and reddish-brown splotches formed on the surface of the crema.

Under-extraction occurs when too few coffee solids are extracted, resulting in a weak, dull flavor. The visual signs are a rapid, high-volume extraction having a uniformly light blond crema."