New Burrs
I recenly changes the burrs on the Mazzer Super Jolly which I have been kindly leant by Jimmy of Urban Beach.
I can’t believe the difference that a fresh set of blades has made to the espresso though! Shots not only taste better, but look better as they are extracting too.
The old burrs (see bottom) are very blunt and I guess they’ve been chewing the coffee rather than slicing, though i’m struggling to work out how and why this makes such a difference to the quality of the ground coffee and the cup.
Espresso grind is supposed to be inconsistent in size, blunt burrs will certainly achieve this, though with a finer grind setting to compensate for the loss of cutting ability. I’m guessing a blunt grinder also produces more heat, thus damaging the coffee to a certain extent. Finally, the grinder performs a lot faster with new burrs, this tells me that the coffee is probably getting getting thrown around and chipped away at for much longer than it would with a good set of blades.
Regardless of the reasons, it all goes to show how pivotol the grinder us in making good coffee… Can’t seem to get good espresso no matter what you do? - check your burrs!
Blogged on my iPhone.
The grinder is so important to the taste of your coffee. No matter how good your coffee machine is if you have a poor qaulity grinder or blunt grinder blades the machine will not be able to fix these problems.
Not only do blunt burrs create more heat but they also create ‘clumps’ of coffee grounds and a very inconsistent grind.
The problem with clumps is that during extraction the water is less likely to pass through these compacted clumps of coffee and favour going around it leading to an uneven extraction.
The problem with an overly inconsistent grind is that the blades will will make far to many ‘fines’ which are very small coffee bean fragments which during extraction will migrate to the bottom of the coffee puck and start blocking the holes in the basket as well as forming a compact layer at the bottom of the puck, thus increasing flow resistance. Did you notice before you changed your blades that your extraction flow rate was slowing down towards the end? this is because of too many fines. To compansate for this we naturally make the grind coarser which is taking us further away from finding the sweet spot in the coffee…
Hope this gives you a bit more insight in to why your coffee is tasting so much better now!
Check out the book ‘Proffesional Barista Techniques’ for a much more indepth analysis on this topic.