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?”
Tell Me Why!
When it comes to coffee, it is difficult to tell the difference between what is fact and what is opinion. With ground coffee, however, there is strong evidence to back up the claim that fresh is better.
Essentially Science says, like the year-old bag of half-eaten tortilla chips sitting in your pantry, coffee beans will go stale the longer they sit, and grinding your beans early only hastens this unfortunate consequence.
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.
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.
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, 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 2016’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. Like 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.