While you don't necessarily want to brew your coffee hot and fresh out of the roaster, you DO want to grind fresh right before brewing to maximize your coffee's tastiness.

What's happening to the good stuff when you use pre-ground coffee?

Encapsulated within that tasty little coffee bean are the aroma and flavor compounds; these are basically what makes our brains perceive great tasting coffee. Once coffee is ground, the coffee loses the best and sweetest aroma and flavor characteristics almost immediately. The longer the ground coffee sits before brewing, the more sweet and fragrant notes will be lost until they’re basically gone.

You can thank the combo of CO2 loss and oxidation (the reaction that happens when things are exposed to oxygen, think of a cut apple turning brown) for the degradation of those flavors and aromas because they actually change the chemical structure of the coffee. Those chemical changes result in flat, stale, and/or bitter tasting coffee.

Strike 1: Loss of CO2

When coffee is roasted, CO2 is created and stored inside the bean. We’re shooting to have the CO2 level in a sweet spot that contributes to both proper extraction and more vibrant flavors and aromas. When brewing espresso, the proper CO2 levels help form that nice, beautiful silky layer of crema that sits on top of the shot. 

In whole bean form, the loss of CO2 (aka de-gassing) happens slowly. But, as soon as the coffee is ground, CO2 dissipates within minutes, causing a flatter, staler, and less vibrant tasting coffee.

To be in that sweet spot of CO2 levels to maximize the coffee flavor potential (or CFP, which is a scientific-sounding acronym that we totally just made up on the spot), we want to wait at least a couple days after the coffee is roasted before brewing*. Then, grind the coffee right before you are going to brew it.

*Off-gassing is really volatile during the first few days after the coffee is roasted and can prevent the coffee from being extracted properly. This also contributes to the coffee being in that sweet spot, and we want to wait least 3-4 days after roasting before we brew it (Learn more here!)

Strike 2: Oxidation

Happening simultaneously with the CO2 loss is oxidation, which are the chemical reactions that happen when the coffee is exposed to oxygen (aka the air). 

In whole bean form, the oxidation happens slowly because there is much less surface area on one bean for oxygen to interact with the good stuff that maximize that CFP. As soon as the coffee is ground, you're greatly increasing the surface area of the coffee because, now, you have thousands of tiny pieces, all with their own surface area to interact with the oxygen. This means that the oxidation process goes into hyperspeed, quickly degrading the aroma and flavor compounds within minutes.

So, what's that all mean?

Now, we’re not saying that if you buy your coffee pre-ground then it’s all over for you. (After all, we do offer the option to order ground coffee on our web store and will grind bags for you in our cafes!) But, the pre-ground coffee simply won’t have the exact same characteristics or flavors as freshly-ground coffee. So, for the best expression of every sip, you should be grinding your coffee fresh, right before brewing.

A note on grinders: Not all grinders are created equal. Grind consistency is just about as important as grinding fresh. If you have a grinder that gives you wildly inconsistent pieces of ground coffee, it honestly may be worth having the coffee pre-ground with a really great grinder because the positives of grinding fresh could be negated by a poor grinder. Here’s some recommendations for coffee grinders we like:

• Baratza Encore - Pour Over/drip

• Baratza ESP Pro - Espresso & Pour Over/Drip

• Fellow Opus 2 - Espresso & Pour Over/Drip

• Fellow Ode - Pour Over/Drip

• Timemore Chestnut Series (manual hand grinders) - Espresso or Pour over/Drip