A bad cup of coffee can ruin the day. So can a stale cup of coffee. Contrary to popular opinion, coffee does go bad, and it does go stale, changing taste & turning over time. How much time, you ask? Now, that would be a product of how the coffee is stored in what form, and a few other factors. There comes a point in all our lives when our coffee no longer tastes like it did when we first opened the bag of freshly roasted beans, despite the best of our efforts and struggles. You tweak the recipe, the grind size, the brewing temperature, everything imaginable, but the coffee can no longer be helped. It is safe to say, the coffee has gone stale and will never go back to what it used to be.
Does coffee go bad?
Coffee doesn’t go bad in the way most of us perceive foods to go bad. Well roasted, well stored coffee will not change color or grow hairy, powdery mold on its surface. Coffee is a dry, processed food product. The water activity in roasted coffee, whether whole beans or ground, is extremely low, making most microbial activity impossible to occur. This is why coffee doesn’t go bad the same way most foods we know do. It does not begin sprouting like some vegetables, it doesn’t begin rotting like some fruits, it doesn’t grow fungi on it like an old, spoilt block of butter. And yet, coffee does go bad. It goes stale.
What is stale coffee?
If you have an old box of nails in your tool box, or even say punched into your wall somewhere, you will see reddish brown patches on it, what is commonly called rust (rust of the iron kind, not the coffee kind! Coffee rust is a fungi, iron rust is oxidized iron). Once you scrub your aluminum pots and pans clean, after a day or two, you will find the shine gone, and the surface looking dull and lacking lustre. This happens because the surface of aluminum is highly susceptible to oxidation, so aluminum on the surface of the pots and pans gets easily oxidized, which in turn forms a sort of protective layer on top, preventing further oxidation. you know how fried foods start smelling off after a while,? Again, the culprit is oxidation. This precise process – oxidation is what makes stale coffee. Thus, stale coffee is oxidized coffee.
Why does coffee get stale?
Coffee goes stale because of a very commonly occurring natural process called ‘Oxidation’. Nothing complex about it, really. Coffee comes in contact with oxygen, naturally present in air everywhere, the compounds present in the coffee interact with this oxygen and get oxidized, thereby changing their flavor and properties, with the end result being coffee tasting off and stale. Coffee, like every other food product is under constant attack from environmental factors – heat, moisture, taints, and so much more. Roasted coffee has oils and fats as well as acids and other chemical compounds, which are considerably susceptible to this oxidation process. Beware, these chemical compounds are not added to coffee by anybody, they are naturally present in all coffee. All food products are made of chemical compounds, as a matter of fact. These chemical compounds are what give coffee its typical and quintessential taste and aroma. When these compounds come in contact with air, they interact with the oxygen in the air, begin oxidizing, and degrade.
Oxygen and moisture are the biggest enemies of good toasting, roasted coffee.
When does coffee expire?
Like most other dry food products, coffee does not have a hard expiry date after which its consumption could make you sick or could be fatally dangerous. However, roasted whole coffee beans will generally stay good for up to 2 to 3 months, though it is best consumed within a month. There is really no fixed rule here, except sooner the better (after the resting period, of course!) Ground coffee beans will go stale faster, in about two to three weeks the change will start becoming apparent. Finer the grind, quicker it goes stale because fine ground coffee will have a greater surface area than coarsely ground coffee. Higher the surface area, higher the exposure to oxygen, hence, quicker the oxidation, and faster the beans go stale.
Once the coffee starts going stale, those flavor nuances of good freshly roasted coffee will no longer be perceivable, and it will remain to be just ‘coffee’. If this sounds very confusing, let me simplify. Good, freshly roasted coffee could have beautiful flavor notes, which are a result of the wide range of flavor compounds that form and exist in roasted coffee. These compounds degrade on oxidation and those beautiful floral, fruity, and other notes will no longer be perceivable. Once oxidation starts and coffee begins going stale, it will start losing those flavor nuances, and after a point the stale aroma and taste will become increasingly apparent.
How to prevent coffee from going stale?
Considering how omnipresent oxygen is, it is practically impossible to completely prevent any oxidation of coffee. The best case scenario is to store coffee in vacuum or to freeze it up. Frozen coffee, if done well, can easily last a year or two, sometimes more.
Some tips to slow down the spoilage of coffee and keep it fresh longer –
- Buy and store coffee as whole beans instead of ground coffee
- If using ground coffee, store as little as possible, get little amounts ground that can be used up in 3-4 days
- Store coffee in a dry, dark place, in an air-tight container
- Do not keep coffee bags open for a long time, take out the amount you need and then seal them close quickly
- If using instant or soluble coffee, store it in an air-tight jar too, they have a much longer shelf life but they are very highly hygroscopic, meaning they will bind with moisture in a snap
Thumb rule – it is all about the storage and bean structure. Take whole beans, put them in an air-tight container, and keep it in a dark, dry, cool place. Or take air-tight tubes or containers and freeze your coffee.
Bigger thumb rule – be as careful and mindful about storing your coffee as you would be about storing your finest wine.
What to do if my coffee has gone stale?
If your coffee has already gone stale, there are a few things you can do, before you decide there is no saving the coffee and dump it in the trash. Though, I would say do not dump it into the trash, you can still find some uses for it.
If you would like to consume it as a beverage, I would suggest trying out cold brewing the coffee. Cold brewing is more forgiving to stale coffee and does not bring out the harsh oxidized stale notes in the coffee as hot brewing would.
You can also try tweaking the salt balance of your water and then use the tweaked water for brewing. There are salt mixes in the market that you can add to the water to make your own special water for brewing, which will help refresh the coffee sometimes. This is not a sure shot trick, but worth a try. The salts are intended to bring out the best from your coffee, and using them to brew stale coffee is just a benefit on the side.
Ideally, using stale coffee in non-food purposes is a better idea. Use the grounds as a coffee scrub, scalp scrub, hair mask, anything on the skincase and wellness side. Use it as a fertilizer for plants. Use it as a room freshener by pouring them into a bowl and lighting a vanilla tealight on top of the coffee. Use it as a deodorizer for cupboards. Use it as a deodorizer for your microwaves and ovens and refrigerators. Use it to scrub greasy pans and pots. Brew it and use it for making beautiful coffee paintings.
There is always the option of composting too.
Long story short, coffee does go bad, but bad coffee will not kill you. It could ruin your day and kill your mood and that could have its own different side-effects, though. You can’t totally prevent coffee from going stale but you can do a few things to slow the degradation down. Once stale, there are some little things to do to use the coffee, but there is absolutely no way to make the coffee taste the way it used to. And the culprit behind this whole drama is what humans and other living things absolutely need to survive – oxygen!
What are your experiences with stale coffee? What do you do once your coffee goes stale? Got any interesting stories to share? Drop me a line in the comments or find me on Instagram – @banjaranfoodie.