QUESTION: Should I grind coffee beans daily? It would probably be easier for me to just grind them all at once, but I want the best-tasting coffee. — Blake C
ANSWER: If you’re considering purchasing a coffee bean grinder or have just received one, you may be wondering whether you should grind your whole bean coffee daily. The short answer is yes. For coffee lovers, the benefits you’ll get from grinding your coffee beans fresh each day (or even for each cup) far outweigh the time you would save grinding them ahead of time.
And if the taste of your coffee is important to you and you’re trying to decide whether to splurge on a grinder, we say go ahead and splurge. Coffee bean grinders are affordable and there are primarily two types of coffee grinders. If you are going to spend your hard-earned money on a coffee grinder it’s a good idea to get the best one you can afford. Hands down, conical burr grinders are the best type of grinder (as opposed to the blade grinder). Conical burr grinders work by crushing the coffee beans and produce a consistent grind for a better cup of coffee. Blade grinders shear the coffee beans and produce friction and heat which can cause the final product to have a burnt taste. All this to say, there’s really no comparison between the quality of the coffee made from freshly ground beans and the alternative. Let’s take a look at why.
Why Grind Coffee Beans at All?
The reason we make coffee from ground beans instead of whole beans comes down to coffee extraction. Grinding the beans brings out as much coffee flavor as possible from each bean. The more surface area available for the hot water to access, the more aromatic compounds will be extracted into the water, and the stronger the coffee flavor of your brew will be. Increasing the amount of surface area available to the water also reduces the amount of time your coffee grounds will need to brew to release their flavor.
Following that logic, the finer you grind your coffee beans, the more flavor your coffee will have. So if you love a strong-tasting brew, grind your beans on the finer side. You should also know that the finer you grind your coffee beans, the more efficient the extraction process will be. This means that a finer grind will provide a more complete extraction, letting you better taste all the subtle flavor notes of your coffee.
How Does Grinding Coffee Affect Its Freshness?
Every coffee bean comes naturally equipped with a protective covering that keeps the oils that produce coffee’s flavor inside the bean where they belong. And inside the bean, those water-soluble oils are safe for quite a long time. However, once you grind the bean and break that protective casing, the clock starts ticking on your coffee’s shelf life, and its freshness begins to decrease from that point on.
A lot of the reasons that coffee loses its freshness and flavor quickly after being ground can be explained by a process called oxidation. Oxidation is simply the way oxygen works with the compounds in your coffee to change them into entirely new molecules. As the molecules change, your coffee begins to lose some of the flavor and aroma that makes it so tasty. This oxidation process begins as soon as your coffee beans are ground, which is one good reason to drink your coffee as soon as possible after the beans have been ground.
Another good reason to grind your beans fresh each day is that it’s relatively easy for the taste of your coffee to be contaminated by odors in the environment. Because the oils that make coffee taste like coffee are so delicate, the coffee particles can be overcome by other odors in the vicinity in a very short time. That means that you could taste those other odors in your brew if you don’t grind your coffee fresh—a very good reason to always grind your coffee beans fresh for the best flavor.
Additionally, your coffee can lose its freshness and flavor to moisture in the environment quite easily. As we’ve mentioned, brewing coffee with hot water works because the coffee oils are water-soluble. That means that any moisture that comes into contact with your ground coffee will begin to extract the oils and dilute them, reducing the amount of coffee taste that remains in the ground coffee. And while it’s true that moisture can cause some loss of flavor in whole coffee beans, it’s very limited thanks to the protective coating on the beans and the limited surface area. That’s why moisture loss becomes much more of a factor once the beans have been ground. Moisture loss isn’t only a concern if the coffee comes into contact with liquid. Humidity in the air can serve as a source of moisture that begins the extraction process as well.
Of note, even before grinding, you should store your fresh beans in an airtight container and if possible find a local roaster so you have the freshest beans available.
How Quickly Does Coffee Start Losing Its Freshness After Grinding?
You may be thinking that freshness is important, but still wonder just how long it takes for ground coffee beans to start losing their freshness and flavor. The answer is that it doesn’t take long at all. The flavors your coffee beans release into the water, called soluble or volatile flavors, can also be released into the air. After just 15 minutes of being ground, your coffee beans will already have lost 60 percent of the aroma they once held.
Another factor that goes into how quickly coffee loses its freshness is the carbon dioxide the beans contain. The process of roasting coffee results in lots of carbon dioxide being stored inside the coffee beans. In the brewing process, that carbon dioxide is responsible for moving the coffee oils from inside the bean into the liquid, changing the hot water from just water to coffee. Just one minute after grinding your coffee beans, 80 percent of the carbon dioxide has already been lost to the air. And as time continues to progress, more and more of the carbon dioxide—and with it, the nuanced flavor and delicious aroma of your coffee—will continue to be lost. This is the difference between a great cup of coffee and a mediocre cup.
So as you can see, grinding your beans when they’re fresh makes a big difference as far as what you’ll taste when you drink your coffee. It’s best not to even wait after grinding your beans to run an errand, take a shower, or perform any other quick task. You should grind your beans fresh not just each day, but for each cup if freshness and flavor are really important to you.
All these factors that cause the clock to start ticking on your coffee’s freshness and taste when you grind the beans—oxidation, moisture loss, and carbon dioxide—are also responsible for releasing the coffee oils into the water you use when you brew each cup. So these aren’t a bad thing. In fact, it’s quite the opposite. Without oxidation, moisture loss, and carbon dioxide acting on your ground coffee, we’d be left with just ground coffee and hot water. We have these processes to thank for every delicious cup of coffee. But as we’ve learned, the process of releasing coffee oils doesn’t wait until you brew the coffee to get started.
That’s why we recommend the best way to enjoy the perfect cup of coffee is to always grind your own beans fresh for each cup—so you get to experience all the complex aroma and delicately balanced flavor of the coffee every time.