When coffee beans are exposed to light, either from direct sunlight or an artificial source, they will begin to degrade, leaving you with stale beans.
Everyone enjoys storing their freshly roasted coffee beans in glass mason jars on the countertop. While they look cool, direct exposure to sunlight or a powerful light source (anything emitting UV) is problematic. It’s not just a problem for coffee beans but also for most foods and organic matter. As UV contains enough energy to induce the oxidation process, significantly impacting the quality of your coffee beans. If left exposed for too long, freshly roasted coffee beans will become stale, leading to a bland and rancid coffee.
Ensuring your coffee beans are stored correctly will keep them fresher for longer. So you should be keeping them away from any light sources.
How Does Light Affect Roasted Coffee Beans?
Once a coffee bean has been exposed to light for long enough, the thousands of chemical compounds inside the beans begin to break down. The chemicals breaking down within the coffee beans are known as photodegradation.
Light, specifically UV light, speeds up the oxidation of lipids, which accelerates the degradation of the coffee beans’ flavors and aromas. Stale coffee will leave you disappointed, and family and friends won’t be too impressed either. Those who have used coffee beans that have been exposed to sunlight describe them as bitter, rancid, and with metallic notes.
I’m commonly asked, “I left my coffee beans out on the counter. Will that light exposure mean when I get back, they’ll be stale?”
And it’s difficult to answer due to so many factors:
- How long have they been left out exposed to light?
- Is it left in direct sunlight or under LED and artificial lights?
- Are the coffee beans whole or ground?
- Are the coffee beans dark roasted or light roasted?
Each of these questions will vary my response. Direct sunlight is usually worse than LED, but this also depends on how strong the LED or artificial lights are.
Whole coffee beans will degrade slower when compared to coffee grounds due to more surface area being exposed. And, if the coffee beans are darkly roasted, you’ll notice they’ll also go stale quicker due to their cell structure.
It’s impossible to give a single answer that covers all responses. With so many variables, the best solution I can provide is to minimize all light exposure and ensure that the coffee beans are stored correctly.
Things To Do To Reduce Your Coffee Beans Light Exposure
Reducing the amount of light exposure your coffee beans receive is simple, with a common-sense approach should get you 99% of the way.
The first option should always be the elimination of light. The quickest way to eliminate light exposure is by placing your roasted coffee beans in a cool, dark place. A cupboard, pantry, or a draw, are all prime locations, as long as the light isn’t shining in, you’ve eliminated one of the harmful elements that will degrade your coffee beans.
By storing them in a cupboard, pantry, or drawer, your coffee beans will be exposed to light when you take them out to grind/brew them. It’s advised to grab what you need, either by eye or weighed, and place the container back into its spot, minimizing the coffee beans’ exposure time to light sources.
If a dark place isn’t an option, or you prefer to keep your coffee beans on the countertop, opt for an opaque container that blocks all light. While some might say opaque coffee containers aren’t visually appealing, I beg to differ. With a simple search online, you’ll find many visually appealing opaque containers that will eliminate photodegradation while adding to the aesthetic of your home.
These two solutions will save your coffee beans from becoming stale too quickly, allowing you to enjoy the freshest possible cup.
Now that you know how light affects your coffee beans, you can begin to take preventative actions. Either purchasing opaque coffee containers or finding locations with minimal light and sun exposure to keep them stored.
By minimizing or eliminating the photodegradation process, you’ll find that you can keep your coffee beans fresher for longer. This goes a long way in ensuring your morning cups of coffee are always delicious.
If you want to find other ways to keep your coffee beans as fresh as possible, you can read my article on storing coffee beans.