[Homeroast] Sour espresso taste

Mike Wilkens mike.wilkens at gmail.com
Tue Jun 5 14:19:09 CDT 2012

Hi Denis, those are all great suggestions.  Regarding temperature, I think 168*F coffee temperature measured in the cup is good or even on the high side.  This is measured after the water has gone through the coffee, and through the air, and into the warmed cup.  At the group showerhead the temperature is much higher.  I measured that too using imperfect methods.

I want to clarify the sour taste if I can.  It is not prickly or tacky, it is the "off" taste like sour milk -- but again, without the tackiness or metallic perception you might get from sour milk.

Your other suggestions are good, I've brewed in an Aeropress everything I've put in the machine, and they all taste pretty good to great.  The blends I've been using lately are Espresso Forte (Peet's) and Toscano (CCC).

My grinder is a used Mazzer Mini, and I've been told that worn burrs can cause a sour taste, and to install new burrs.  I'm doing that next, we'll see if that has an effect.

Regarding cleaning: is minute rice more effective than manual cleaning?  I've been using a toothbrush & vacuum cleaner to get gunk off there.  I'm sure there are oils left after my cleaning though.  I don't taste bitter or rancid in my AP brews...

I should've decalcified & cleaned out the New Baby more throughly (I only took off the showerhead), but the Classic is brand new.

It seems like you covered all the bases.  There's channelling, which is supposed to be another possible cause of underextraction.  At this point I believe I'm preparing the puck fairly well.  We'll see what the new burrs do.


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