If you use a coffee or spice grinder you know that, over time, residue builds up inside and on the blades, and it'll eventually, well... get a little gross. The good news is that if you're facing a funky, gunk-filled coffee grinder, there's an easy trick to get rid of all that buildup and get your grinder clean and back in action: use rice.
According to Kitchn, running dry, uncooked rice through a grinder can help blot up oils and fragments from coffee and spices and get rid of any weird smells. Plus, it's a cleaning method that won't affect the future taste of whatever you're using the grinder for.
It doesn't matter what kind of rice — just use (or use up!) whatever you have at home. It might not get your grinder visibly spotless, but considering you can't just dunk it into the sink, the rice method is a great way to maintain your hard-working appliance. And the best part? It's super simple to do, and only takes a few minutes.
There's a full tutorial (with plenty of photos) on Kitchn and the whole thing truly couldn't be easier to do.
On Kitchn → How To Clean a Coffee or Spice Grinder
You can use this method weekly if you need to, or just use it whenever you see build-up or notice weird smells.
Note: The rice method only works for blade grinders—if you use a burr grinder at home, CNET (which, by the way, also backs up the rice method for blade grinders) has helpful instructions for properly taking it apart and cleaning it out.