Quick Answer: Of course, you can grind coffee in a blender or food processor. Even the weakest units can make quick work of roasted coffee beans.
But even though it's a quick solution, the truth is that it's not ideal. There are a few issues that make grinding coffee in a food processor or blender, the sub-optimal solution.
Let's explore them a bit more...
Grinding Coffee in a Blender or Food Processor
Here is a video of me doing the job in my Nutribullet. Just note that I overloaded it here and ground more than for a single cup (not recommended if you want the best flavor.)
1. Load Up Your Coffee Beans in Small Batches
One of the biggest mistakes that people make is loading way too many coffee beans in their blender all at one time. You should only blend as many as you need.
You don't want to grind your beans ahead of time because the quality will degrade as the ground coffee beans age.
Normal coffee grinders are designed to grind only what you need for a single cup or single shot of espresso, but with a food process or blender it can be easy to go way overboard.
So that said, make sure you know how many beans you're going to need (by weight is best) and load them into a blender.
It's also good to note that a small blender like the Nutribullet or Ninja are good for small batches.
2. Pulse Lightly to Your Preferred Grind
As you may already know, there are several different-sized coffee grinds depending on what you're trying to brew up.
If you want to do a fine grind, you're going to want to run the blender for as long as possible without generating too much heat.
That said, you should still do it in tiny little pulses.
This grind-style is best for things like espresso. Some people like it because it makes a strong cup of coffee if you put it in a drip, but if you're sensitive to over-extracted flavors than go for something more course.
If you're using a Chemex or other sort of drip apparatus, then you're going to want to do a medium grind.
Since you don't want to make it fine, be sure to pulse and process very conservatively.
Also consider that if you've overloaded the blender, you may get an uneven grind. If this happens, pulse once and then remove the blender from the base the move things around a little bit.
Then, put it back on and do another pulse until you've reached a medium grind.
If you're using a French Press, then you may want to do a course grind. This will probably be one of the hardest ones to do in a blender.
You need to be extremely careful when doing this, though. One extra pulse and your grind can turn medium-style.
Two or three extra pulses and you can end up with a fine grind.
That said, start with one pulse and then move the beans around inside the jar as needed. If you have some beans that you haven't hit yet, you want to make sure that those get close to the blades before you resume.
3. Reload If Needed
If you want to grind more beans, simply reload a little bit and repeat the steps above.
Let me reiterate again, that less is more when grinding coffee beans in a blender or food processor.
Since you only want to grind what you need, you're better to under-load the jar than overload it.
Things to Be Careful Of
If you get the grind too fine, you risk over-extracting the coffee or getting little fines in your french press. Know the type of grind you need and pulse with big increments in between to get to that grind.
Too much heat during the grinding process can ruin your beans. The only time you want your beans to be exposed to heat is when they are getting extracted from your brewing water.
The cooler you can keep your beans before they come in contact with the water, the better. Otherwise you're going to end up losing some of the beautiful flavor and end up with an underwhelming cup.
By grinding in small pulses, you should be able to avoid heat problems, especially if you have a high quality blender that vents itself.
You probably already know that moisture and humidity is no good for coffee beans. That's a given.
But, what you might not have considered is that there may be extra moisture droplets lingering around in your blender or food processor.
Just a small droplet can get your beans wet and make them stick ot the sides of the jar.
Before you start grinding, make sure that the inside is thoroughly dried. If it isn't be sure to wipe it down with a paper towel.
Is a Grinder Better?
The fact is that for this particular application, these two alternative appliances are good in a pinch, but aren't the ideal way to grind coffee beans.
Coffee and espresso grinders are designed specifically for dosing the correct amount of coffee beans and grinding to the correct consistency.
While some rudimentary grinders are nothing more than glorified food processors, consider this...
A burr grinder has two burrs, basically two wheel-shaped rough edges, which turn in different directions to create the most uniform particle sizes possible. This results in even extraction and a delicious cup of coffee or espresso.
This is something that simply cannot be achieved with blades.
But hey, unless you're a true coffee lover you may never notice the difference. Personally, I sometimes enjoy a home-brewed cup of Folgers just as much as what I can get from my local high-end cafes. So different strokes for different folks.
So let's do a quick recap...
- You can certainly grind coffee with a blender or food processor if you're in a pinch. Just be sure to use small batches and follow the steps and head the warnings above if you want to get the best results.
- Be sure to check for extra drops of moisture in your jar before you start. You don't want your ground coffee beans getting stuck to the sides.
- Also be sure to know which grind you want beforehand so you can do the correct amount of pulses.
- A high-end grinder is always going to be technically better for the job. That's just the way it is. However, if you're just a casual coffee drinker and not a connoisseur, you probably won't notice the difference. And you can still create a great cup without an expensive grinder.