March 23

Does Coffee Go Bad? Tell-Tale Signs

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Millions of people around the world have a loving relationship with coffee. To this day, it's the first exciting thought I have as my feet hit the floor in the morning.

Whether it's motivation to get out of bed, your favorite afternoon pick-me-up, or how you like to finish a meal, we all want our coffee to be strong, flavorful, and most of all...

fresh

The undeniable fact is that while coffee doesn't expire quickly, it can lose its greatest flavor attributes quickly if not handled with care. 

Coffee is made up of hundreds of compounds like carbohydrates, proteins, and lipids. We know that with time, these compounds undergo physical and chemical changes that ultimately alter the aroma and taste of coffee.

To ensure keeping your coffee fresh for as long as possible, priority number one is slowing down these reactions. While the science can get complicated, the methods of coffee preservation are relatively simple. So grab a cup of your favorite Joe and let's get to it. 



-Does Coffee Go Bad?

Similar to tea and many other dried goods, coffee’s expiration date on the package is more of a guideline of freshness, rather than a date of going bad overnight. Coffee doesn’t so much expire much as it loses its aroma and taste over time. 

The Big Question: How long do coffee beans last?

The Simple Answer: Until they stop tasting good. 

Although there's almost always an “expiration date” on coffee beans, there is no exact definition of when coffee actually expires. Manufacturers come up with a length of time that usually reflects the time the coffee remains "palatable," or at its peak freshness.

Expiration depends on several factors. The type of roast, the form the coffee is in, and the storage environment will all determine how long your coffee will last. 

For example, coffee beans will last quite a long time due to their relatively small surface area. Ground coffee, on the other hand, oxidizes much more quickly, due to its 10,000 X increase in surface area, creating much more exposure to its surrounding environment. This creates lots of space for oxygen to get in and oxidize the flavor/aroma components of your coffee. 


-How Does Coffee Go Bad?

Let's break down the major contributors of coffee degradation. The first, and probably the most critical, is moisture. 


Moisture - Any moisture that gets into your coffee stash will start the oxidation process. When coffee comes into contact with any water, then aromatics, oils and acids are released. As these molecules are lost, so is the coffee character. Moisture is your coffee's worst enemy (until you brew it, of course). Mold can also thrive in a moist environment, creating a potential health hazard. At the very least, the mold could create some very unappealing flavors. 

Heat- heat can also alter the taste of your coffee. Roasted coffee beans should be kept away from heat until ready to brew. Exposure to heat can cause coffee beans to lose flavor rapidly. Think of heat as a catalyst. Molecule degradation is happening no matter what, but heat speeds this process up substantially. Keeping your coffee cool and in a dark place will keep your beans fresh. 

Light - lighting has the most significant effect on beans directly after the roasting process. UV light increases the rate of coffee oxidation, thus coffee should be kept in a dark container, and always in a dark place after each use. 

Air (Oxygen) - Oxygen has acquired quite a positive reputation (being responsible for our ability to breathe and what not), but as you'll soon realize, oxygen is not our friend when it comes to food preservation. Not only can nasty bacteria and mold thrive in aerobic environments, but oxygen is responsible for the oxidation , and therefore the flavor loss of many of our favorite foods. 

Coffee contains oils, so it can actually go rancid when exposed to the elements listed above. Rancid beans can contain low levels of mycotoxins (toxins produced by mold) which can even survive food processing. Make sure to always get your beans from a reliable source.


-How to Tell Your Coffee Has Gone Bad

Our noses are amazing inspectors of food. We are capable of delineating between thousands of distinct compounds by our scent. Our brain processes this information as we sniff; our smell and taste are ultimately linked. 

One of the most powerful strategies in evaluating your coffee quality is to simply smell it. Get your nose in there and give those beans a big whiff. If you can no longer smell that rich and distinctive coffee aroma, your coffee has probably gone stale. Coffee has a ton of volatile compounds and can rapidly change after being exposed to environmental elements. If the coffee no longer has a delicious “coffee” smell, it probably won’t taste very satisfying. 

The smell of coffee is ultimately a very important part of its flavor profile after it’s brewed. The more aromatic the beans, the more flavorful the brew will be.

Proper Coffee Equipment Maintenance: It's also possible your beans are fresh but your equipment isn't clean. It’s important to clean your coffee makers often, so as to not harbor harmful mold or bacteria. These critters can easily make it into your coffee, and at the very least, contribute some unpleasant flavors to your brew. To keep your coffee fresh and pure, clean your devices often. Most coffee-maker manufacturers will include a cleaning maintenance guide that can be found in the users manual or online. 

Remember to trust your senses when testing your coffee for freshness. If you're hesitant, throw it out. There's no reason to expose your taste buds to something inferior, or possibly harmful. 


-Our Recommended Products for Storing Coffee

For those who take their coffee flavor seriously, here are some air-tight containers that can help preserve the integrity of your coffee beans. 

-Freezing Coffee...is it a Good Idea?


Although reviews are mixed, there is no definite answer to this question. If you have some unopened bulk coffee beans that you know will go unused for a while, it’s okay to freeze them for a few months. If done properly, freezing coffee does have its benefits, such as using it for espresso to extract a richer, thicker body. 

However, once you take coffee out of the freezer, you cannot let it thaw. Any moisture that condenses on the beans will start the extraction process. 

Some say that if you freeze ground coffee, it will dissolve in hot water quicker, producing a richer flavor…

and many say that once you freeze coffee, the smell and taste will never be the same.

So, what to do?

I don’t advise freezing coffee, unless your situation absolutely calls for it. Brew your coffee as soon as possible after purchasing, and enjoy a hot, fresh cup daily. Freezing can lead to unwanted taste changes in your beans, so it’s always a risk you must be willing to take. 


If you're still unconvinced, take your coffee and stick it in the freezer. Brew it up and see if you notice any flavor loss/changes. I think the validity for freezing coffee should be on a brand by brand basis. I currently freeze my Peet's Brazilian Beans and they hold up just fine. But I've also had some bad experiences with freezing other types in the past. 

It's also possible to experiment with freezing some brewed coffee in ice cube trays, and using them for coffee smoothies, iced coffee, or making coffee ice cream. After cubes are frozen, they should be transferred to a freezer bag to avoid absorbing other aromas from your freezer (trust me on this one)


-Instant coffee 

Instant coffee is essentially brewed coffee that has had the moisture removed. It has the longest shelf-life of all the forms, and can be kept, stored properly, for up to 20 years in your cupboard!


-Cold Brew 

If you haven’t tried cold brew, you’re definitely missing out! This type of coffee is made with cold or room temperature water, and is essentially a concentrate. It has a different flavor profile and is often sweeter than hot coffee. It lacks the bitter notes that are extracted when put into contact with hot water, and many prefer this taste.

Cold brew can be stored in the fridge in an airtight container for up to 2 weeks, but NOT if diluted with water. Flavor will start to degrade after 1 week, so don’t forget about that cold brew in the fridge! 

Check out our delicious Cold Brew Recipe. Once you make your first batch, you'll be hooked!



-Shelf Life of Brewed Coffee

Although it's not ideal for flavor, brewed coffee can be left out on the counter for up to 12 hours, and reheated on the stove. Microwaving coffee is not the way you want to reheat, as it changes the flavor and dynamics of your coffee.

If coffee is put into an airtight container or thermos just after cooling, it can be kept in the fridge for a few days and used to make a nice iced coffee, or reheated on the stove. The longer your coffee is left out in the open, the quicker it will lose its appeal. This is obviously not ideal for a fresh cup, but if drinking strictly for a pick-me-up, it should get the job done.  

“I put instant coffee in a microwave oven and almost went back in time.”

      - Steven Wright



-How to Regain Coffee Freshness 

The closer to the roast date that you brew your coffee, the fresher it’s going to be. The moment coffee is roasted, it starts the process of oxidation, thus slowly getting more stale by the day. 

There is no strong agreement on how quickly coffee beans go stale, as stated by James Hoffman in his book, World Atlas of Coffee. Freshness after roasting highly depends on the producers method of packaging. The majority of roasters use a triple-ply foil insulated bag. This special packaging prevents air getting in, but allows oxygen to escape via a small valve in the bag. Science is amazing, isn't it!

There is also a process called nitrogen flushing (as used by Lavazza), where the oxygen is flushed out and temperature stays regulated, allowing for slower oxidation. 

As soon as the bag is brought home and opened, oxygen gets in and the beans slowly start to oxidize.

Again, to slow the oxidation process down after opening, coffee should be stored in an airtight container (specifically a coffee bean canister) in a cool, dark and dry place, and used within the following weeks for maximum freshness.

Peak flavor of your coffee can vary greatly, depending on the type of beans used, the roast, and the brewing method. 

Lastly, for maximum freshness in each cup, try to only buy as many beans as you will use in 3-4 weeks. While buying in bulk has its perks, it can ultimately lead to inferior tasting coffee. Just some food for thought. 

-In Conclusion 

We've concluded that "bad" coffee is not characterized by an expiration date or a foul smell, but more by a lack of aroma.

To get the freshest cup, grind beans only as needed, and use beans that have been roasted no more than 1 month prior (if already opened).

Coffee is a fragile food that should be respected. If we treat it right, it will reward us in many ways. There's really nothing like a fresh, hot, rich cup of joe.

Thanks for reading, and if you have any questions or comments please feel free to contact me! 

Cheers,

Michael 




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About the author

Michael spends his days eating, drinking and studying the fascinating world of food. He received his Bachelors Degree in Food Science and Technology at the University of California, Davis and spent much of his time at the school brewery. While school proved to be an invaluable experience, his true passion lies in exposing the hidden crannies of food for the cooking laymen.

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