Freshly Ground Coffee - Why It Tastes Best
Since I first opened my eyes to the world of coffee beyond Starbucks, I’ve been told that freshly ground coffee is better than pre-ground coffee. I didn’t know why, and I could never get a better answer than a pretentious scoff from the know-it-alls, yet I accepted their unquestionable logic and found that it is true: fresh is better.
However, maybe it’s due to an unresolved issue with authority (12 was a hard year) or maybe it’s my OCD (self diagnosed), but I had to know why: why is freshly ground coffee better? Is it just personal taste? What does Science have to say about it? Am I just trying fit in with all the “experts?”
There are three factors that contribute to this tragic degradation: oxidation, moisture, and CO2 depletion.
Before we take a look at these three factors, here’s a great video of an experiment using the same coffee grounds over different periods of time.
The complex compounds within your coffee beans are what create your brew’s aroma and flavor. Not all of these compounds are very stable, which means that they can change quickly.
Through oxidation, a process by which compounds interact with air molecules to create different molecules, certain desirable flavor and aroma compounds are released from your coffee beans. When you grind your beans you kick start this oxidation process, which is a good thing if you brew right away, but not if you wait too long (1).
"...once those beans touch air, the oxygen begins to zap their flavor and make them smell different almost immediately by causing coffee solubles to either degrade and oxidize..." - Julia Calderone, Business Insider
Oxidation is what gives your coffee its unique (depending on the roast) flavors and aromas, but oxidation will carry on whether you are brewing or not. By brewing with a fresh grind, and not pre-ground coffee, you are making the most of your coffee’s deliciousness.
Here is something you may not know: the oils in coffee beans are water soluble. In case my peculiar brand of sarcasm has no effect on you (I don’t blame you, it’s terrible) that was a joke. Obviously coffee oils are water soluble (laugh now).
Water solubility is a great thing, otherwise the coffee we enjoy wouldn’t taste or smell as good as it does. However, it doesn’t take an entire cup of boiling water to dissolve those precious oils, because even the moisture in the air can dilute your beans (2).
So unless you live in the Sahara, the simple act of exposing your delicate beans to your home’s AC-moderated atmosphere can sabotage their integrity, and grinding only makes it worse. When you grind your beans, you create more surface area for moisture to dissolve those oils, and therefore hasten the dilution.
Alright, so this point is pretty similar to the previous. CO2 is the main agent that transfers your coffee beans’ oils into your coffee, and when you grind your beans you create more surface area for the CO2 to escape. Coffee beans are already very porous, so grinding only makes it worse, which is a good thing if you are brewing right away (like you should).
If you aren’t careful, improperly storing your beans can cause them to quickly lose most of their CO2 (3), and grinding only makes this harder. If you let your grounds sit for hours or days, you are essentially wasting the one mechanism responsible for your coffee’s great flavor.
Other Reasons For Fresh Grounds
Besides those three (awesome) reasons to grind only right before brewing, there are two others to consider as well.
Here is a scary thought: all those other odors floating around your kitchen are slowly infecting your ground coffee, especially that onion you just finished cutting. If the thought of onion-flavored coffee frightens you (chills down my spine), then don’t buy pre-ground coffee beans.
And if you think your grounds are safe in the fridge, guess again. Although the cold might neutralize your sense of smell, there are still plenty of odors roving around your refrigerator that you don’t want settling into your grounds.
Brewing great coffee is all about control. You are Lenin, and coffee is your USSR. The more control you have over each aspect of the brew process, the better shot you have of making exceptional coffee. Just don’t be a Stalin.
When you grind your own beans you have greater authority over grind size, which has a significant impact on flavor. Most methods of coffee brewing, like espresso, pour-over, and AeroPress, require different grind sizes, but buying pre-ground coffee limits you to only one.
Choosing to grind your own beans puts another step between you and your beloved coffee, but even if you only brew with one method, having the ability to slightly change your grind size can substantially impact the quality of your coffee. To find yourself a great grinder, click here for my list of 2019’s best hand options.
Unlike the stoic snob behind the counter at the instantly Instagrammable coffee house, Science has opened its mouth and shared some knowledge bombs. As with most food items, fresh is better, and coffee is no exception.
These flavor-packed little stimulants are sensitive and will only relinquish their best if handled properly. Whereas pre-ground coffee has already lost most of its delicate aromas and oils, freshly ground coffee beans are ripe for brewing. So yes, in case you haven’t guessed so yet, you’ll need a great burr coffee grinder to help with this.
Let me know your thoughts in the comments below, and if any of your friends ask you, “Why is freshly ground coffee better?” then send them this article. Make sure to also check the article 'Does coffee go bad?' and never worry about a stale and bitter brew again.
Frequently Asked Questions
Why should I grind my own coffee?
You should grind your own coffee to ensure you’re getting all the aroma and flavor you’re paying for. Whole beans can last for about a month with careful storage; ground coffee begins to deteriorate in 30 minutes or less - good if you’re having pizza delivered, not so much if you’re keeping ground coffee in your kitchen.
Why is ground coffee cheaper than beans?
Ground coffee is cheaper than beans, typically, because it uses less expensive coffee beans that are roasted and ground for a lower price point. The coffee beans sold as whole beans, particularly by specialty coffee roasters, are usually from better producers, often from single origin farmers, and represent a much higher quality product. We say that there are things to save money on, and things to save money for, and coffee is definitely in the second category.
How do you keep ground coffee fresh?
You really can’t keep ground coffee fresh - it begins to deteriorate after about half an hour. If you absolutely must keep ground coffee, for instance if you are traveling and don’t have access to a grinder (we’ve been there, we won’t judge), pack it in an airtight container and keep it away from light and heat. But once you’re accustomed to truly fresh coffee, you’ll find that ground coffee - even in an airtight package kept in the dark - loses a portion of its flavor every day.
- Calderone, J. (2015, September 28). Here's why coffee gets stale if it sits out for too long. Retrieved from https://www.businessinsider.com/why-coffee-gets-stale-when-sitting-out-oxygenation-2015-9
- Ross, C. F., Pecka, K., & Weller, K. (2006, December 07). Effect of Storage Conditions on the Sensory Quality of Arabica Coffee. Retrieved from https://onlinelibrary.wiley.com/doi/full/10.1111/j.1745-4557.2006.00093.x
- Milos, G. (2010, October 06). The Coffee-Storage Conundrum: How to Keep Beans Fresh. Retrieved from https://www.theatlantic.com/health/archive/2010/10/the-coffee-storage-conundrum-how-to-keep-beans-fresh/64118/