Some of you may be aware that I've recently added timer based pre-infusion to my Linea. It works by delaying the pump activation by a user set time. Right now, I have it set to 10 seconds.

Is there a guide to use to understand what varying the time of pre-infusion accomplishes for taste? Any guides to help me dial in mine without burning through pounds of beans?

Its a good question and I wish I could answer with any authority at all (but I can't)

For me, I think in terms of different types (or levels) of PI. First is wetting the surface of the puck, second would be wetting the puck partway through (maybe 1/2 way) and third would be complete saturation until the first drops appear on the basket screen surface.

It might be worthwhile to try different levels of PI on consecutive shots and see if you can discern a difference in taste. I've never done anything like that so it might be interesting to read about.

My new machine has line pressure PI and I've been playing with it, but I can't say I notice a dofference in TASTE using it. It seems to be a more forgiving process, and I do like to taper the pressure at the end of the shot...but again I've not done any side-by-side taste testing to note a specific effect.

another_jim wrote:There may be more to it than I ever suspected.

Tim Tailor at Ipsento, who has retrofitteed variable preinfusion on his Linea, uses an SOP of extending the time for lighter bodied, more acidic light roasts and decreasing it for darker roasts. This worked at our get together yesterday with a very lightly roasted Kenya. In fact, it worked better than my SOP of lower dose/finer grind.

That's very interesting. As you know, my tastes run towards the fruity/acidic flavors and ever since I did my goat dance at Caffe Streets, I've been on a quest to replicate their pull at home. The whole reason for pre-infusion for me was in an attempt to get closer. If I remember correctly though, Ipsento has a profiling setup that Chad came up with that's much more than simple pre-infusion which may explain why there's more to their's than you suspected.

Thanks Dan for the links, they were very informative!

another_jim wrote:There may be more to it than I ever suspected.

Very interesting!
I have a couple of brighter beans on the bar right now that I'll have to try extended PI for. Yesterday I roasted the El Salvador DP Monzano (it made "juicyfruit gum" shots last time)