Burr vs. Blade Grinders: Why Does It Matter?
Guest post written by Sam Ellis
Some people still think that the only way they can improve the taste of their coffee is by buying better coffee or by using a more sophisticated coffee machine. They don’t realize that a very simple method to improve the taste of their daily brew is to change the way they grind it.
Before I started taking coffee seriously, I had owned and used several blade grinders. I never quite managed to grind beans to the same quality that I would find in packs of good, ground coffee at specialty coffee shops. The improvement I expected from having freshly ground beans simply didn’t happen because I was using blade grinders.
Long story short (if you know a bit about coffee, I don’t need to explain this to you), I eventually found the answer when I invested in a slightly more expensive grinder for my coffee – burr grinder.
So what are burr grinders and why do they generate a far superior grind for our coffee?
Burr vs. blade coffee grinders, the basics
Many people starting out with fresh coffee will often go for a blade grinder. I certainly did. Blade grinders are cheap; there is no question about it. They work by using a rotary blade which chops up the coffee beans inside the bowl of the grinder. There is no ability to control the grind size and getting a perfectly even grind is nearly impossible (at least beyond most people’s skills).A burr grinder, on the other hand, will pass the coffee beans through two (or more) burrs which will crush the coffee, achieving an entirely even grind. They have a setting with which you can select the grind size – allowing you to grind your coffee to suit the brewing method.
Good burr grinders will be considerably more expensive than blade grinders, but if you are looking to have good coffee, the investment will certainly pay itself back over time.
Here’s where we need to get a bit technical. Bear with me.
As has been hinted above – one of the major benefits of a burr grinder is the even grind size. Even grind sizes matter more than you think in how your coffee tastes. That’s because a particle size will change the coffee extraction when your coffee maker passes hot water through it.
As you probably know, “extraction” refers to the process of dissolving solids (flavor) in the coffee beans into the water. Smaller particles will extract faster whereas larger ones slower, meaning that with a variety of grind sizes, you will have varying degrees of extraction in the same brew.
The result is some of your coffee getting over extracted and some under extracted. This matters because over-extracted coffee brings with it bitter flavor compounds ruining your brew while under extracted coffee will taste sour and even salty. The sourness in under-extracted coffee comes from the fact that some compounds, which balance acid tastes in the coffee beans, have not yet been dissolved into the water.
Under-extracted coffee will taste flat and lack complexity while over-extracted coffee will completely overwhelm your senses with an unpleasant bitterness.
The distinction in particle sizes leads us to the second major benefit of a burr grinder vs. a blade grinder. The setting for grind sizes that you can make with burr grinders but cannot with a blade grinder is central to being able to make an excellent cup of coffee.
You might be aware that espresso coffee uses a very fine grind (and Turkish coffee an even finer one – more on that below) whereas drip coffee requires a coarser grind. Armed with our understanding of over and under-extraction we can now see why this is so crucial. Espresso will push the water at high speed and pressure through the coffee powder, whereas drip coffee will slowly pass the water through the grinds.
The more time the water spends in contact with the coffee grinds, the more coffee solids will be extracted. We balance this by using the right grind sizes – for espresso, the fine particles of the coffee will ensure that we extract the good flavors in the short time that the water spends in contact with the coffee.
So far so good, but there is more. Not only is your type of coffee machine an important variable when deciding about the grind size, but even different roasts, beans, and blends will have more or less of the bitter, sweet and sour flavour compounds meaning that they require different grinds.
A burr grinder lets you determine the best setting for your machine and your chosen coffee by allowing you to vary grind size with the turn of a knob. Once you’ve found the perfect setting, your burr grinder will ensure that your beans are ground to the perfect size day after day.
Feel the Burn
This might seem like an already strong case for burr grinders, but there is still one more benefit to mention. Here it comes down to physics. As you may remember from your science classes, when you rub two surfaces against each other, there is friction which in turns leads to heat.
Inside your blade grinder, the rapidly spinning blades will be rubbing the coffee beans against the sides of the grinder, generating enough heat to make the coffee feel slightly warm when you take it out of the grinder. This heat starts altering the flavor of your coffee beans while grinding, extracting some of that flavour into the air rather than into your coffee cup.
The one situation where a blade grinder is suitable
Is there any case where a blade grinder is preferable? Well, bar being on an extremely tight budget, a burr grinder will always be the preferred choice. And when you think that a grinder may last you five years or longer, the initial investment is not that huge.
There is, however, one type of coffee for which a blade grinder is suitable. This is where I get back to Turkish coffee: most burr grinders cannot produce the incredibly fine coffee powder that Turkish coffee requires. With a blade grinder, on the other hand, you can simply leave it to grind your coffee to the minimum particle size it allows. The challenge of mixed particle sizes is therefore in this case, not a problem (though you’ll still have the loss of flavour by heat).
Do you have any questions about the burr vs. blade grinders? Ask in the comments!