About Grinding Coffee
Most people choose the convenience of ground coffee. After all, it’s available everywhere and easy to load into the coffee maker. However, it is worth noting that ground coffee expires at a faster rate than whole bean coffee. While Grumpy Goat Coffee provides you the freshest coffee possible, and the fresher your coffee, the more flavor you will experience in your cup when it’s brewed. Grinding coffee just before it’s brewed is critical to ensuring the freshest cup of coffee every time…but don’t worry, we are still happy to provide you with ground coffee.
We strive to share our passion of coffee with you, therefore we want our customers to understand the two main types of coffee grinders, each with pros and cons of each. There are also the various grind types that will be explained.
The Two Types of Coffee Bean Grinders
There are two main kinds of coffee bean grinders made for home use: the “coffee mill” sometimes called the burr grinder, and the more common propeller grinder. We at Grumpy Goat Coffee use the Bunn G3 commercial grinder, which is a burr grinder.
The burr grinder grinds the beans using two burrs, or serrated discs. You set the type of grind you want, load the beans into the chamber, and start grinding. Ground coffee collects in a second chamber ready to be brewed, in addition to being able to pick the grind type to match how you plan to brew your coffee, the fact that the burr grinder allows the consistently ground coffee to exit the grind process and fall into a separate chamber ensures consistency during the entire grind process.
When compared to the propeller grinder, the burr grinder will take a little longer to grind the beans. Additionally, propeller grinders are typically less expensive than the burr grinders and become the entry level grinder of the up and coming coffee aficionado.
The more common grinder is the propeller grinder, known for its two-sided single blade that spins and chops the beans at the same time. This is the grinder that you typically see for sale at Target, Bed Bath and Beyond and other big box retailers.
After loading the beans into the chamber and grinding, you decide when to stop grinding the beans based on personal experience and through the transparent cover of the grinder. If it is early in the morning and you aren’t paying attention, it is easy to over grind your coffee with a propeller grinder.
Unlike the burr grinder, there is no second chamber into which consistently-ground coffee collects. This requires the user to have a trained eye and experience in “pulsing” the grinder to achieve the desired grind…as you are in full control. Additionally, as the propellers in the grinder get dull, the longer the grind process can take thus resulting in more friction heat added to the beans, which can result in an inferior cup of coffee.
Since the propeller grinder is far more common, the price tends to be lower and depending on your budget this can be an advantage (remember, whole bean coffee ground just before brewing will result in a fresher cup of Grumpy Goat Coffee). While the propeller grinder is faster, our experience hasn’t led us to believe that it is significant enough to consider it an advantage over the burr grinder.
Of everything you might encounter when brewing at home, grinding coffee is arguably one of the most crucial steps, as grind size alone can dramatically change the taste of your cup. Grind size and consistency can be the difference between one of the best cups you’ve ever had and a bitter, undrinkable mess.
Now onto the grind types…
Why grind size matters
When it comes to grind size, there are three factors which make the biggest difference: contact time,extraction rate and flow rate. To put it simply:
- The extraction rate of coffee grounds increases with a larger surface area.
- To increase surface area, grind the coffee finer.
- The higher the extraction rate, the less contact time is needed.
- A finer grind can reduce the flow rate of water, increasing the contact time.
Knowing this, if you have a brew method with a short contact time, the grind should be finer. In an immersion brewer, which steeps coffee grounds in water for several minutes, the contact time is much higher and, thus, requires a more coarse grind than most other brew methods. To put this in other words, brewing through a re-usable K-cup would require a grind finer than what would be used if you were using a French Press.
If the contact time is too high or the grind is too fine, it will result in an over-extracted brew which can add bitterness. If the grind is too coarse or the contact time is too short, the coffee will turn out weaker than expected.
While many think this is a science, we at Grumpy Goat Coffee believe there is just as much art to this process as well. Afterall, you are brewing a cup of coffee that you enjoy!
Different types of filters, pressure and temperature can also play a part in determining grind size, but most brewing methods operate between 195 and 205 degrees Fahrenheit (90.6 and 96.1 degrees Celsius) with little to no added pressure (aside from Espresso machines).
With an array of different brewing methods, knowing which grind size to use is crucial to getting the best possible cup. Below they are listed in order of extra fine to coarse.
- Turkish coffee calls for an extra fine grind size, similar to that of powdered sugar.
- Espresso is a brewed through using pressure (approximately 9 bar) to force water through compacted coffee grounds. Due to the very short contact time, this method requires an extra fine grind size.
- The AeroPress is a popular single-cup manual coffee maker. It’s similar to a French press in design and use, though users have come up with a laundry list of ways to brew. Recommended grind size is between medium and fine, depending on steep time.
- Siphon Brewers or Vacuum Pots use pressure to force water into a chamber holding the coffee grounds. Once the steep has finished, heat is removed, which creates a vacuum in the lower chamber and pulls the water through a filter. This method calls for a medium-fine grind size.
- Pour-Over brewers come in many different sizes and shapes. While different brewers and pour over designs require varying grind sizes to control the flow rate of water, a general guideline for the pour over methods is medium to medium-fine grind.
- A Stovetop Espresso Maker or Moka Pot is a coffee maker which uses steam pressure to force water upwards through a filter basket full of coffee grounds. The contact time is quite short, but the pressure (approximately 1.5 bar) is a bit higher than your typical manual brewer. It calls for a medium grind size.
- A Single-Cup Coffee Maker, such as a Keurig or Verismo machine, is a drip brewer method, similar to the commercial drip brewers found in cafes. The contact time is fairly low, meaning it calls for a medium to medium-fine grind size, comparable to that of table salt.
- Drip coffee is what you typically get from a cafe or coffee shop. It’s made in large batches and contact time is dictated by a small hole in the bottom of the brewing basket, so recommended grind size varies between medium-coarse to medium.
- The French Press is an immersion brewer. Water is added to coffee grounds and allowed to steep for several minutes before straining out the grounds. This method typically calls for a coarse grind setting. While a grind type other than course can be used, it will result in more sediment in the cup.
- Cold Brew, unlike other brewing methods, is done at or below room temperature and takes between 12 and 72 hours. Due to the low temperature, the extraction rate is low, regardless of grind size. A coarse or extra coarse grind size is recommended, as it’s easier to filter. A finer grind size will work just as well (with a slightly shorter steep time), but can cause the final product to appear a bit cloudy and require additional filtration.
Of course, all the above recommendations are just that — recommendations. You are welcome to change them to your taste preferences and specific brew method.
As a general hint, if you feel your cup of coffee is a tad weak, try a slightly finer grind size next time. Or if the coffee tastes too strong or slightly bitter, test with a slightly larger grind size to see if it achieves the taste you are after.
