David Schomer writes in his "The Professional Barista's Handbook", that it is best to leave the puck in the porta-filter because it keeps the porta-filter's heat more constant.
Is this still considered wise to do ? Or is it better to knock the puck out, immediately after the shot, as is advised in many other places ?
FWIW, I make 5 to 6 double shots during a day.

when I grew up in Italy I always remember every barista doing so
BUT
longer you leave a puck in, depending on the thermal and temperature of the machine,
it could bake the puck in the portafilter and leave residues at the bottom of the basket making it not has easy to knock out clean
so in my personal opinion and experience I will say no

This is the sort of magical coffee knowledge that James Hoffman rightly derides in his awesome talk on reinventing espresso. This is also characteristic of the type of 'knowledge' that doesn't transfer to home use at all.



If your idle times are short, then this practice makes little or no difference. If your idle times are long, then you're letting lots of gunk dry and harden on the screen and also letting a lot more oil line your group's feed tube and 3-way valve. I'd say leaving the puck long-term runs the risk of clogging your screen, fouling your brew path (which will have a negative impact on the taste of your espresso), and just plain makes your cleaning regimen more of a pain in the butt. I wouldn't do it.

No don't leave it, unless you want a dirty portafilter that's harder to wash.

Ton wrote:David Schomer writes in his "The Professional Barista's Handbook", that it is best to leave the puck in the porta-filter because it keeps the porta-filter's heat more constant.

Technology has outdated this. The advice was for Lineas that had groups a few degrees cooler than the brew boiler and no gicleurs. The spent puck acted as a flow restrictor when flush-heating the group prior to the next shot. The newer LMs don't need heating flushes.

Should I leave the puck in the portafilter after a shot ?

Maybe.

On an e61, knocking out the puck will cool the group by a degree or two for a while. If making a second shot in short order, leave it in. If more than about 15 minutes, knock it out.

How long you can leave it depends on

• single or double basket
• bottomless or regular PF
• dose
• ambient conditions

The first time you forget that there's coffee left in the basket, and you come back to the machine a few hours later, or the next day, and you smell what was left in there.. that will be the last time you leave used coffee in the basket.

And the James Hoffman video is a must see. Entertaining, thought provoking, and educational.

Thanks for the replies. I now know for sure what to do.

The James Hoffman lecture is indeed great btw !