How Long Can Coffee Sit Out?

Coffee is one of the most famous drink signatures worldwide, thanks to its flavor and scent. Yet, how long can coffee sit out before it becomes spoiled?

Of course, brewed coffee can’t stay in good condition forever. Many factors affect its safe-to-drink time, such as temperature, storage methods, air exposure, etc. However, this article has all you need. So, read until the end for a detailed explanation. 

How Long Can Coffee Sit Out? (Full Explanation)

Brewed Coffee Shelf Life

This drink will be the most delicious when enjoyed right after it is made. However, there are always some cases where you won’t be able to finish it at once. If you leave the drink for too long, you should consider whether to remove it or not.

This will cause a loss in its wonderful aroma and begin to have an unpleasant and weird taste.

In general, pure black coffee has a longer shelf life. If you haven’t touched that drink, it can sit out for up to 24 hours at room temperature. So although you can safely enjoy it, it won’t taste as delicious as just brewed.

On the other hand, hot milk coffee is only drinkable for around one hour at 90-140 Fahrenheit and two hours at 40-80 Fahrenheit. The truth is that milk can decay and spoil quickly. So, if you leave it in the kitchen cabinet too long, the milk will change to a sour flavor. 

It will happen to every milk-based beverage, such as latte, frappuccino, mocha, and other standard drinks purchased at a shop. Thus, keep in mind not to drink it and throw it away immediately. 

Factors That Affect Coffee Quality

Oxigen

The leading cause of bad-going coffee is oxidation. Its unique flavors are created from easy-to-volatile aromatic molecules that readily oxidize when exposed to air.

When it comes to coffee oxidation, there are 2 oxygen sources:

  • Dissolved oxy in the water used for brewing.
  • From the air. 

This oxy then combines with the compounds and free hydrogens in the cup of joe. As the amount of hydrogen molecules decreases, the pH will rise. This is because of the available acidity in hydrogen ions. The longer this process lasts, the more bitter the flavor is in your drink.

The oxidation will happen in both ground coffee and brewed one. When it still has a chance to be exposed to oxy, it can keep degrading and reacting with some components in the air. So although it doesn’t become bad and drinkable, its aroma and taste will diminish significantly.

Heat And Light

Brewing coffee is just the first step in a complex series of many chemical reactions. Once you use hot water to penetrate ground coffee, those atoms emit a powerful smell right away. Then, its flavors and oils begin to fade.

That’s why it’s recommended to utilize water between 195 and 205 degrees Fahrenheit (approximately 90-96 Celsius degrees). Indeed, boiling water causes it to over-extract, resulting in a harsh taste. 

The higher temperatures the drink suffers, the faster the oxidation process happens. So, light can act as a catalyst to fasten this process. 

So, the cold brew flavor can last longer. Meanwhile, a coffee pot resting on the hot plate of your coffee machine will contain more bitterness.

Moisture

Moisture doesn’t affect the brewed drink. Yet, this factor is the worst enemy of coffee beans. As mentioned before, when coffee absorbs water, it will release its oils, flavor, and acids.

If you used these damp beans to brew your drink, the flavor is terrible, without a doubt, not the coffee taste. 

How To Reheat Coffee?

When it comes to reheating your cuppa, do you think a coffee maker can do that? Unfortunately, that’s one of the most common mistakes. 

Most of these makers can keep your drink warm after brewing. Yet, if you put your brewed drink in its canister and switch on the heating element, your drink is likely to scald the bottom.

After all, your machines might end up being clogged inside due to coffee residue. This might destroy the pot and certainly damage its flavor. Thus, we suggest 2 straightforward and effective ways here to reheat your cup of joe:

Using A Microwave

A microwave is a piece of common equipment in every kitchen. It can heat almost everything quickly. 

Although this may immediately reheat your drink, it will have a big effect on the flavor. This is because any odors leftover from when the drink was first brewed are broken down while reheating it in the microwave. Due to this breaking down process, the flavor will fade.

If you’re in a hurry or just want a cup of hot coffee without the perfect taste, this is the way to go. 

  • Remember to use the medium heat level for 1 minute. 
  • Continue this process for 30 seconds until it reaches the desired temperature. 
  • The coffee will not burn as a result of this. It’s critical to ensure your drink is in a microwave-safe container or mug.

Using The Stovetop

This method will allow you to regulate the temperature better to keep the flavor longer. If you attempt to reheat it to a high temp, it might burn your pot and taste scorched. Instead, keep the temperature low since the burnt drink is the worst.

  • Pour your coffee into any pot and place it on a low-heat stove. 
  • Wait until steam begins to rise, but do not allow it to boil. 
  • Pour the drink back into your mug and take a sip!

Risks Of Drinking Spoiled Coffee

This section doesn’t mention its changing flavor. However, it might cause vomit sometimes due to the disgusting smell.

Fortunately, coffee doesn’t spoil in the same way that bread molds or a banana rot. So, if you accidentally drink a bit of spoiled drink, it will not cause harmful consequences for you. However, if you drink a lot, it can be different.

As we know, consuming spoiled food will easily cause diarrhea. Thus, if you drink a lot of spoiled coffee (2 or 3 cups), the chances of suffering from diarrhea will be higher, especially if you are ill.

The spoiled drink can harm your stomach. The acidic composition of the brewed coffee stimulates the body to generate more bile (the alkaline, bitter substance that causes the stomach to churn). They can gradually build up in your gut and result in the situation of the runs.

3 Obvious Signs Of Bad-Going Coffee

Mold

The most apparent sign of bad-going brew coffee is mold development. It can happen if you leave your drink for a few days or weeks. When you see mold (light color streaks) cling to the mug side or around the container, your drink is spoiled.

Furthermore, you won’t smell the vibrant aromas of freshly brewed coffee but the rancid odor. So, there is no reason to drink it. You should discard it immediately when you see this indicator. Then, remember to clean your mug thoroughly.

Flavor

Although you haven’t seen mold development in your cuppa, it might also have been spoiled already. 

Another sign of bad-going cuppas is their taste. Not to mention that it has changed in flavor when stored for a period of time. Finally, the spoiled one has terrible taste. It is a combination of stale smell, and over-bitter flavor mixed with sourness.

Even a sip can make you shiver. Spoiled food might also harm your health if you eat it many times. Thus, pour it into your sink right away and make a new cup to enjoy.

Color Change

The color of coffee is proportional to the roasting level. The longer you roast the beans, the darker it becomes. This is due to the inherent sugar in beans changing from sweet to caramel to burnt during the roasting process.

Yet, a standard cup of coffee comes in brownish-black color. So, once you have left it for a time, you might pay attention to its color. If the color becomes lighter, it can be a sign of spoiling.

Yet, this kind of changing color is difficult to realize. If you are still in doubt, try taking a sip to see whether the taste changes too much. When you ensure it goes rancid, don’t hesitate to throw it away.

4 Methods To Store Brewed Coffee

Do Not Add Dairy

Some people prefer to put milk in their drink to reduce bitterness and better texture. Also, we cannot deny milk can bring us many nutritional benefits.

Yet, as mentioned before, adding milk or any dairy can shorten the shelf life of leftover drinks. This is because dairy spoils much faster than coffee, especially when you keep it out at room temperature. As a result, you’ll want to leave it in original black while you intend to store it.

If you have mixed milk together, then find other ways to preserve it below. It may not last as long as the original version, but it will give you a good amount of time that might be enough for your next drink.

Remove From The Heat Source

It’s critical to remove the coffee pot from the burner when the brewing is finished. Because of leaving it on that burner, it will quickly oxidize and turn sour.

Then, you can pour it into a high-quality insulated thermos. It is airtight and can keep the flavor of the coffee without making it bitter or off-tasting. Furthermore, it is convenient to take away. You can enjoy your drink whenever you like.

Put It In The Refrigerator

Refrigerating brewed coffee slows the oxidation process and extends its shelf life. However, remember that you don’t want the drink to absorb the flavors from other things in your fridge, so keep it in a firmly sealed mug or container.

It may seem self-evident, but almost everything can last longer when kept in the refrigerator. You can extend the quality and longevity of your drink if you brew it and store it at a lower temperature. When stored this way, it’s probably safe to drink for up to a week. 

Yet, you shouldn’t preserve it for that long. Consume it whenever you can. Of course, it won’t be very tasty. It will still taste stale compared to when it was freshly made, but it’s greater than throwing out a whole cup.

Freeze And Make Ice Cubes

You may simply freeze a whole pot or more instead of worrying about refrigerating and consuming it in 5 or 7 days. However, before putting it in the freezer, check if the container is airtight.

If you want to preserve it for a longer time, freezing is the best one. In the freezer, it’s OK to keep coffee for up to two months. Yet, the flavor and quality will have faded. Remember to note the date you brewed and freeze it on the freezer container or plastic bag so you will know the expired day to use it before that.

Another way to preserve it is to make coffee ice cubes. You can use them to cool down hot drinks, retain your iced coffee cool without diluting the flavor, or produce tasty coffee-flavored smoothies.

It’s simple to make these ice cubes. You simply fill an ice cube tray with the remaining drink and place it in your freezer.

Some people have ideas to make flavored ice cubes with cream and sugar or other interesting ingredients like vanilla syrup. You can keep the ice cubes in trays or put them in a zip bag once they’ve frozen.

FAQs Of How Long Can Coffee Sit Out

1. How many times can you reheat a coffee?

The short answer is: not too many. According to health experts, you can reheat coffee 2-3 times before it starts losing its flavor and nutrients.

Reheating coffee more than that can make it taste very bitter and burnt. So, if you’re going to reheat your coffee, make sure to do it within 24 hours, and no more than that.

2. Is reheated coffee carcinogenic?

The simple answer is NO. According to the National Cancer Institute, there is no significant link between coffee and cancer. Reheating coffee does not increase the risk of cancer.

Some urban legend says that reheated coffee causes dioxins (a type of carcinogen) to form. However, this claim is unsupported by scientific evidence.

3. What can I make with day old coffee?

If you have a cup of coffee that’s been sitting out for a while, there’s no need to throw it away. There are actually a number of recipes that call for using day-old coffee. For example, you can use it to make:

-Coffee rubs for meats

-DIY body scrubs

-Frozen coffee cubes

-Coffee liqueur

4. What does spoiled coffee taste like?

The first signs of coffee spoilage are usually a sour or fermented taste. The coffee will also start to smell vinegary or like over-fermented beer.

As coffee continues to spoil, the flavor will become more and more rancid until it is completely undrinkable. Spoiled coffee beans will also change color, turning from brown to a murky black.

When coffee goes bad, the best thing you can do is discard it and make a new batch. Spoiled coffee will not make you sick, but it will not taste good.

5. Does reheat coffee destroy caffeine?

The simple answer is no. Caffeine is heat-stable, meaning that it doesn’t degrade at high temperatures the way other compounds do.

So, regardless of how many times you reheat your coffee, the caffeine content will remain constant. However, keep in mind that the longer coffee sits out, the more bitter it becomes.

This is because coffee oxidizes when exposed to air, which causes the beans to release more of their oils. These oils are what give coffee its characteristic flavor and aroma.

However, they’re also responsible for making coffee taste bitter when it’s old. So, if you want to enjoy your coffee’s full flavor potential, it’s best to drink it fresh.

Caffeine is one of the main reasons people drink coffee. It’s a psychoactive stimulant that can improve focus and vigilance, among other effects.

6. How do you know if coffee is bad?

The answer to this question is both straightforward and difficult. On one hand, you can tell if coffee has gone bad by its taste, smell, and appearance.

If it tastes bitter or acrid, smells sour or vinegary, and looks muddy or cloudy, then it’s probably time to ditch it. On the other hand, it’s not always easy to tell if coffee is bad just by looking at it.

Sometimes, even when it tastes and smells fine, it can still make you sick. This is because coffee beans are absorbent and can absorb bacteria and mold from their environment.

So, even if your coffee doesn’t look or smell bad, it might still be contaminated.

7. Does day old coffee still have caffeine?

Yes, coffee that’s a day old can still have some caffeine content. However, its levels will be significantly lower than when it was first brewed.

Caffeine is a natural compound in coffee beans. It’s also water-soluble, meaning that hot water can extract it from the beans during brewing.

Once brewed, coffee will start to lose some of its caffeine content. This happens because the drink is no longer in contact with the beans.

Over time, more and more caffeine will evaporate or get absorbed into other elements, like the cup.

8. Can bacteria grow in coffee?

Yes, bacteria can grow in coffee. However, they don’t affect the quality of your coffee.

In fact, some bacteria are essential for the fermentation process that creates different types of coffee, such as cold brew and sour coffee.

So, if you’re wondering if can coffee goes bad and makes you sick, the answer is no. On the other hand, spoiled coffee won’t make you sick.

But, it will taste bad and smell off. Also, mold can grow in coffee and that can be harmful to your health.

9. Can you drink coffee that sat out all night?

Technically, you can drink coffee that sat out all night. However, it’s not recommended to do so.

Coffee is a mixture of hundreds of different chemicals. These include water-soluble molecules such as caffeine and acids, as well as oils.

When coffee sits out, the oils start to evaporate into the air. This makes the coffee go stale and lose its delicious flavor.

Additionally, these oils can oxidize and turn rancid, making the coffee taste bad. So, if you leave your coffee out overnight, it will be safe to drink. But it won’t taste very good.

10. Is it safe to drink day old coffee?

Generally speaking, yes, it is safe to drink day old coffee. However, you might not enjoy its taste or quality as much as you would if it were freshly brewed.

Of course, this is only true if you follow certain storage guidelines. For example, coffee that has been exposed to air will go bad more quickly than coffee that has been properly sealed. Additionally, hot coffee will degrade more quickly than cold coffee.

In general, then, you can expect your coffee to be at its best for up to 24 hours after brewing. After that, it will still be safe to drink, but it may not taste as fresh or be as enjoyable.

11. How can I make my coffee last longer?

If you want your coffee to last longer, there are a few things you can do. First, store your coffee in an airtight container. This will help to prevent air from causing it to go bad.

Second, store your coffee in a cool, dry place. Heat and humidity can also cause coffee to degrade more quickly.

Finally, you can try storing your coffee in the fridge. This won’t work for all types of coffee, but it can help to extend the life of some types. Just be sure to reheat your coffee before drinking it, as cold coffee may not taste as good.

12. Can coffee go bad and make you sick?

Generally speaking, no, coffee cannot go bad and make you sick. However, there are a few exceptions to this rule.

First, if your coffee has been stored in an airtight container for an extended period of time, it may develop mold. Moldy coffee is not safe to drink and can cause nausea and vomiting.

Second, if your coffee has been exposed to rodent droppings, it may also be contaminated and should not be consumed.

In general, though, coffee that has gone bad will simply taste sour or bitter. It is unlikely to make you sick unless it is moldy or contaminated.

Conclusion

Brewed coffee is tasty and fascinating. If you have any leftover coffee, find a suitable way to preserve it. Don’t leave it at room temperature. Enjoy your morning drink later this way.

To sum up, this article has provided the ultimate answer, “how long can coffee sit out?”, along with some knowledge and valuable tips for brewed coffee. Hopefully, it is helpful for both novices and coffee enthusiasts.

Almost 20 years already spent committed to coffee and more than 3 years of experience as a barista at Starbucks. Madelyn Doyle graduated with a Bachelor’s Degree in Nutritional Science from the University of California and finished the Coffee Skills Program at the Specialty Coffee Association (SCA).