February 7


Is Light Exposure Bad for Coffee Beans?

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You might have heard that storing your coffee away from light helps keep it fresh longer, but this isn’t always true! In fact, some sources say that coffee should be stored in dark places. In contrast, others say it’s best stored with only moderate light exposure (like fluorescent lighting). So what gives?

Light exposure is bad for roasted coffee beans as it can make them decay faster through photodegradation. However, experts have mixed messages about whether unnatural light (such as fluorescent or house lights) is okay. For ideal storage, ensure your beans aren’t exposed to light.

Below, I’ll review the how and why of storing coffee beans. Then, I’ll wrap up with the best ways to store your coffee beans (spoiler alert, the biggest tip is to throw them out when it’s the time!). 

How Light Affects Coffee Beans

Coffee snobs and those who could care less about their coffee alike can both agree–a pot of boiled coffee in your office’s kitchen is not coffee. Even if it comes out of the coffee pot just right, something about it as it sits over time makes it taste awful. Is it light exposure? Or is it oxygen exposure? Is it both?

Light exposure causes the beans to go stale and lose some flavor because of a process called photodegradation. The same goes for their aroma and acidity. This means that if you’re using an airtight container to store your beans, it could be a problem if you keep them in a place where there’s lots of artificial light—near windows or under fluorescent lights.

Roasted Coffee Beans and Light Exposure 

It’s time for a short lesson on light exposure. You may have heard that UV light is bad for your skin, but did you know it’s also bad for coffee beans?

Light is made up of different wavelengths that range from visible light to x-rays and gamma rays. UV (ultraviolet) rays are shorter than visible light waves. While they can be harmful to human health, they aren’t visible to the naked eye; however, they can still cause damage to your precious beans!

While your instinct may be to store your coffee in the dark, you should know that UV light is more damaging than visible light. While UV light isn’t visible to the naked eye and looks white, it can damage the flavor of your beans and their surface. Exposure can cause them to go stale faster and even moldy if left in too much sunlight for too long.

When used for short periods for storage or transportation. If a bag has been exposed to light for an extended period, such as months or years, then it may be something that causes you concern.

Coffee Beans and the Oxidation Process 

While the oxidation process is natural, it can cause your coffee beans to go stale. 

The reason is simple: oxygen (O2) in the air tends to interact with certain compounds found in coffee and cause them to break down (this is also known as enzymic browning). Once this process begins, all sorts of nasty things happen: there’s a loss of aroma and flavor and an increase in bitterness. In short, oxidation makes your favorite roast taste more like burnt toast than anything else—and nobody likes burnt toast!

The good news is that light exposure doesn’t affect this process. So while light may be harmful if you leave your beans exposed too long (especially direct sunlight), it won’t make them go bad any faster than they would have otherwise done so on their own accord…

The Verdict: Light Exposure Is Not Great Depending On The Type, But Oxidation and UV Are Bad For Coffee Beans

All in all, exposure to light is bad for coffee beans. But there are some differences between UV light and visible light. 

The most important thing to know is that UV light (also known as Ultra Violet) can cause a chemical reaction in your coffee beans, making them stale or rancid more quickly than they would otherwise. When a bean absorbs this sort of radiation, it undergoes a process called photooxidation–meaning it oxidizes faster than normal and loses its natural taste faster.

How To Store Your Coffee Beans

Coffee beans are sensitive to heat and moisture–as well as light exposure–which can cause them to lose their flavor over time. If you want your coffee beans to stay fresh, store them in a cool, dark place. While keeping them on the countertop is tempting, so they’re always visible and available, this is not the best idea.

Storing Your Coffee Beans on the Counter

Your coffee beans are okay in the package they came in, as long as you got them from a reputable roaster. Now, if someone just handed you a cup of coffee beans, that’s different. Most recommend storing them in an airtight container (like a sealed Ziploc bag) in your pantry or cupboard. If you do that, you don’t have to worry about light exposure ruining them.

However, many are out there if you want a fancy tool for it. Here’s a video with recommendations for coffee canisters, which block from sunlight, oxygen, and humidity:

Keep your coffee beans away from heat sources such as stoves or radiators. Don’t leave them near a hot oven or stovetop where they might be exposed to steam or heat from an active burner. If possible, store your beans in an airtight container instead of resealable bags (such as Ziplocs) since this will help prevent any moisture from getting inside.

The Proper Amount of Time To Keep Coffee Beans

When you open a bag of coffee beans, they will last up to two weeks if stored properly. 

As you probably have noticed. Coffee beans are typically roasted, packaged, and sealed for freshness in vacuum-sealed bags or jars. Once the seal is broken, oxygen comes into contact with the beans and changes the chemistry of the beans. Oxidation happens quickly; within minutes after air exposure, coffee beans lose their flavor and aroma.

The best-by-date is just a guideline, so if there’s no sign of spoilage (like mold or discoloration), it’s probably safe to keep using those beans until their flavor has faded. However, if you notice any spoilage–mold growing outside of the baggie or discoloration on some beans–then throw those bad boys out ASAP! They just don’t taste as good anymore.

Keeping Your Coffee Beans Fresher Longer

You don’t have to drink six cups of coffee daily to make sure you get the most out of your bag (and please don’t, your heart will thank you!!). Instead, you can try the following:

  • Buy from reputable roasters. Most coffee roasters only sell their beans for a few months after roasting them, so make sure you buy from a reputable source that will rotate their stock regularly.
  • Buy small amounts at once. If you’re buying in bulk, keep the beans in an opaque container away from sunlight and heat sources like ovens or microwaves (these cookers are notorious for producing heat spikes). This way, you’ll be able to consume it all before it goes stale–or at least use it up within a few weeks of buying it.

If it makes sense for you and your budget, you can support your local coffee shop by stopping in for your daily cup of joe. It may be cheaper than buying coffee beans just to throw them away!  


Light exposure will cause beans to go stale and lose their aroma, acidity, and flavor. You should store your coffee in a cool place away from direct sunlight to prevent this from happening. Otherwise, if the packaging is opened before its expiration date passes, then there really isn’t anything harmful about letting some sunshine through before using them, so long as you do not let them sit out longer than necessary! 


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