The Big Mistake You're Making When Grinding Coffee Beans
In your quest for brewing a flawless cup of coffee, there are lots of factors to consider, from finding your favorite roast, to nailing the perfect water temperature. There's also the freshness of the coffee bean to consider. Eat This, Not That! says going for pre-ground coffee is a surefire way to a stale cup. If optimal flavor trumps convenience in your coffee ritual, you'll want to start your day with freshly ground coffee beans.
Just how fresh? Coffee Brew Guides recommends grinding your beans no more than 20 to 30 minutes before brew-time. During the grinding process, your coffee beans are exposed to oxygen and they start to decay immediately — and flavor plummets. Freshness declines over time with whole beans, too, but since beans have markedly less surface area for oxygen to wreak its havoc, coffee beans' shelf life for peak flavor is a little longer: about two to three weeks.
How to keep coffee from going stale
The secret to ultra-fresh coffee is as straight-forward as it sounds: Grind your beans right before you brew to maintain acidity and body (via Serious Eats). Make sure to start off with fresh beans. Eater suggests limiting your coffee bean purchase to only enough to last the week. Store whole beans (and coffee grounds if you must) in an air-tight container away from excess light and heat — both of which can further degrade the nuanced and delicate flavors of your dark, toasty French roast, or your densely-sweet and spicy Ethiopian, leading to an all-together flat and unsatisfying cup of joe.
Take another tip from Coffee Brew Guides and use a vacuum-sealed container to ensure maximum freshness. And don't ever put your precious coffee in the freezer! This won't extend the flavor of your favorite brew. On the contrary, freezing coffee results in the beans or grounds extracting excess moisture — mucking up your perfect cup.