Sharp burrs are vital to a consistent and quality grind, and replacing your burrs after extended use can make a drastic difference in your espresso.
The burrs of the coffee grinder crush the beans and push them through a small gap between two burrs in the grinder. Some grinders use flat burrs, while others use conical burrs.
Whether your coffee grinder has conical burrs or flat burrs, you must clean them regularly to keep them in good condition when grinding coffee. If you have been regularly cleaning them, using the grinder for some time, and noticing some changes in the coffee.
For example, if you notice any unusual sounds such as grinding, rattling, or metallic clinking, it could indicate that the burrs are worn or misaligned. If you notice significant signs of wear on the burr surfaces, such as dull edges, chipped edges, or uneven wear patterns, it's time to replace them.
While extraction may be the easiest way to measure wear on the burrs, ultimately, deciding when to change the burrs is a matter of taste. Duller burrs produce lower and less even extractions, resulting in cups that may taste increasingly muddy, flat, soury, or astringent. Switching to new, seasoned, burrs will give you bright, sparkling, and transparent flavours once more.
Images from left to right: very worn tool steel burrs, worn titanium coated burrs, new ceramic burrs.
Keyword: Changing grinder burrs; worn or misaligned burr, new burrs refresh coffee flavor