Ideal extraction rate over time for espresso shots

#1: Post by **boldstep** » October 7th, 2019, 8:17 pm

Hi

I shared a video of me extracting Vivace Dolce on my Linea Mini with a friend and he said that it looked good but noted it sped up a little too much at the end. That got me wondering what an ideal espresso shot should look like in terms of the flow rate over time. Eg should the flow at the end of the shot be twice the volume per unit time as the beginning or should you aim for it to be as constant as possible. Seems like I am missing some basic extraction theory. Also what parameters can I control to prevent it from speeding up?

Thanks in advance! Oh here's the video I shared:

http://www.youtube.com/watch?v=P_Xkp45DLNQ

#2: Post by **jpender** » October 7th, 2019, 8:42 pm

Cute baby!

October 7th, 2019, 8:48 pm

Observant and thank you!

October 9th, 2019, 2:09 pm

No takers on this question?

#5: Post by **shawndo** » October 9th, 2019, 3:06 pm

That is typical for a normal pump espresso machine. I think most don't worry about. Levers and flow/pressure profile machines can reduce the flow/pressure in the later stages of the shot if desired.
I've tried, but never noticed any difference in taste but you may have a better palate than me and might be worth it to pursue.

PS that was a pretty pull. If It tasted good you're ahead of the curve!

#6: Post by **C-Antonio** » October 9th, 2019, 5:35 pm

some can nitpick on everything... how can they enjoy it?

Im not really sure how your friend can say that it sped too much at the end, independently of everything if you dialed it in and the results in the cup are good thats whats important. The flow does speed up once the puck is wet anyways and a change in finesse, age etc could affect it (AFAIK), cant judge those things from the video...
Maybe the only thing you are missing is minutia that wouldnt change anything in the cup... you forgot one key information in your question: how did that coffee taste?

October 9th, 2019, 7:26 pm

The shot tasted great to be clear. My friend's question had me wondering if this is a parameter others are monitoring and adjusting for to hit some ideal extraction rate. It seems not unless you are doing some pressure profiling.

#8: Post by **biketo** » October 11th, 2019, 11:19 am

I don't have a Mini, but I do know that your interval times seem pretty consistent with a standard 8mm gicleur. If you changed for a 6mm you would get a longer time to first drop and a longer shot time. Here's an old thread about it: How to install a new gicleur on a La Marzocco Linea Mini

#9: Post by **cpro48609** » October 11th, 2019, 8:41 pm

Bottomless PF shots with a great camera always makes a mouth watering video lol. You can almost taste it coming out, good job.
Unless you have a way to change the flow rate (slayer paddle etc) I don't know of a way to change the flow as it's happening real time?
If your input to output weight ratios are happening within your desired time (usually 20-30 seconds) and it tastes great, then I think all is well. Actually all would be great as you would be enjoying some super good coffee!

#10: Post by **guijan12** » October 12th, 2019, 2:34 am

Indeed mouth watering video!
To me it looked good and if it tasted as good as it looked, why change it....

Cute baby, yes