Because, if you do it; then obviously you will notice that the aroma of your coffee is already lost when you regrind them in your coffee grinder.
Can I re-grind my coarse coffee?
What happens when you grind your coffee beans?
And when the coffee beans are ground, they release oils that alter their flavor and aroma. Also, the consistency in the coarseness or fineness of coffee affects how quickly you can extract compounds during the brewing time. So, try experimenting with different grind sizes and techniques! How to Grind Your Coffee Beans Properly? 1.
How to grind coffee beans for French press?
This method will work best for French press coffee, since the grounds are best if they are coarser than those used for drip coffee. It is also a bit labor intensive, but will get you the results you need in a pinch. The easiest way to grind your coffee beans using a rolling pin is to put them in a plastic bag.