Thursday, March 14, 2013

When to remove the spent grinds from the portafilter?

Should we leave the used spent grounds in the portafilter or knock them out right away?

Elektra Portafilters with and without spent grinds
Photo courtesy of Not to be reproduced
or copied in any format. Copyright 2013.
There are two schools of thought that need to be evaluated. In all cases, the portafilter handle should always remain on the espresso machine while powered on. The main reason is that the portafilter needs to be hot to the touch prior to extracting an espresso.

A not-so-well known, but highly educated coffee roaster in Italy has once advised us to leave the spent grinds in the portafilter until the next extraction. The sole purpose was to stabilize the heat dissipation in the grouphead, especially an E61 grouphead connected to a heat exchanger (not double boiler machine). The reasoning is that the grouphead would overheat less. Although we have not tested this, this is a possibility. The second reason is sweating in the portafilter basket - water vapor would build up in the basket.

There are a few reasons against leaving the spent grounds in the portafilter handle:

a) the espresso puck can stick to the dispersion screen,
b) there would be an increase of rancid coffee oils passing through the dispersion screen, and
c) in a commercial environment, it would increase wait times for cleaning.

Update Mar 14, 2013 4:05pm - We just left a spent coffee grind puck in the portafilter for 3 hours. The puck knocked out great, except for the residual stuck to the basket.

What are your thoughts?


Andrés Villaveces said...

Perhaps the best is following the advice of the Italian coffee roaster - leave the spent grinds in the portafilter until next extraction, but (of course, as always) completely clean by using the machine's pressure to clean the dispersion screen before next use - if puck sticks to the dispersion screen, cleaning it that way will unstick the puck, and moreover many of the rancid coffee oils should wash away. (Of course, this is complementary to the real cleaning by back-flushing with blind ultrafilter...)

Tiemo Mehner said...

I think the missing factor is "time until the next extraction". In a commercial environment where the next extraction is seconds or minutes away it makes a lot of sense to leave the spent puck, at home where the next extraction may be hours away I would remove after extraction: just take a good whiff of a several hour old puck...