What Happens If You Overgrind Coffee Beans?
Yes, it's certainly possible to push a button and get a cup of coffee or swing by Starbucks on your way to work, but something is satisfying about preparing a cup of coffee from freshly ground beans. Why? The Coffee Bean & Tea Leaf explains that it's the process of grinding a coffee bean that releases all the good stuff — the oils and aromatics that you plan to extract with water. And while Easy Home Coffee acknowledges it's not the most straightforward process, freshly ground beans will yield the best flavor. However, to fully enjoy it, consuming them the day of is advised since they don't stay fresh for long as they start to oxidize and lose their aroma.
And, because no one can complicate things like coffee geeks (or purists, if you prefer), the kind of grinder you choose and the degree to which you grind those beans also matter. Coffee Tea Warehouse lays out the benefits and drawbacks of the two basic kinds of coffee grinders: blade and burr. The latter type of grinder will produce the most evenly ground coffee, but even after you've made that investment, you still have another decision to make: How fine should you grind your coffee beans?
Overgrinding coffee beans leads to a bitter flavor
According to Homegrounds, the reason we grind coffee to different sizes or levels is to get the ideal amount of extraction from the beans, and different brewing methods require varying degrees of grinding. Under-extracted coffee from beans ground too coarse will lead to a taste that is salty, acidic, and tart. Over-extracted coffee beans that are ground too fine will result in a cup that is tasteless and acrid.
Alliant Coffee doubles down on avoiding over-ground coffee, stating: "Under-extracted coffee can be fixed by using more water or hotter water, brewing longer, using finer coffee grounds or more coffee grounds. Over-extracted coffee can be fixed by starting over." You may have a cup of coffee that's plenty caffeinated, but it won't necessarily taste good.
In general, The Coffee Bean & Tea Leaf explains methods like the french press, with a long brewing time, benefit from a coarser grind. A medium or medium-coarse grind is the best size for automatic drip coffee, while espresso requires one that's finer. Your grind should be guided by your brewing method, and it may take a little trial and error to dial in the level that creates your ideal cup of coffee – but it's oh, so worth it.