Reheating reorganizes the chemical makeup of the coffee and totally ruins the flavor profile. Some things just don't work to reheat, and coffee is one of them. It's always best just to brew a fresh cup."
If your morning cup just got cold, you can warm it up without worrying too much about safety, but bacteria love coffee, so if your cup has been sitting all night, it's best to just pour it and start over.
We don't recommend drinking day-old coffee, especially if it has gone rancid and has accumulated an unpleasant smell and/or taste. This happens often when brewed in large batches like in coffee urns. Brewed coffee also has a tendency to accumulate molds especially when kept outside the fridge.
Reheating the last few sips of your morning coffee in the microwave or on the stovetop won't cause any harm other than a bitter cup of joe. Just be sure to reheat it in a a heat-safe container. It is safe to reheat your coffee, as long as you don't mind the increased bitterness that may result.
As long as it's free of additives, plain iced coffee will be fine to drink for up to 24 hours. That said, don't be surprised if it turns into a watered-down mess within an hour or two. Iced Coffee With Milk: No shocker here, but iced coffee with milk is only good for two hours at most.
Is the flavor of the coffee affected? Just as coffee beans go rancid after about two weeks, brewed coffee can start to taste bad after about 30 minutes, or the time it takes for the coffee to cool. Then you have about a 4-hour window before the oils in the coffee start to go bad, which further alters the taste.
Brewed coffee can be stored in the fridge for three or four days—hello, iced coffee. As for cold brew, it'll keep for about a week in the fridge if stored in a lidded container. Happy drinking, y'all.
Microwaving coffee messes with its chemical makeup
Reheating reorganizes the chemical makeup of the coffee and totally ruins the flavor profile. Some things just don't work to reheat, and coffee is one of them. It's always best just to brew a fresh cup."
The best way to reheat your coffee is by heating it up on the stovetop at a low temperature. All you need is a pot and your lukewarm coffee. Fill a small pot with the cold (or lukewarm) coffee. Place it on the stove and set the heat to low or medium heat.
It's commonly known that reheating coffee, whether in the microwave or by another method, makes coffee taste more bitter. This is due to the presence of chlorogenic acids. Coffee beans contain large concentrations of these acids, which belong to the aromatic phenolic acid group.
You can drink it but it may taste rancid and bitter. Day-old coffee won't teeming with harmful bacteria like some other beverages, but its taste doesn't compare to a fresh pot. However, if you added creamer or milk then it's probably not safe to drink.
Reheating coffee is entirely safe, so you can sleep happy if you want to keep reheating your gone-cold cups. Just be careful if your coffee contains milk or cream. We'd steer clear from reheating coffee with milk in it if it's been out of the fridge for more than two hours. Just to be on the safe side.
Hendon states that under almost all circumstances, reheating coffee won't cause it to lose caffeine. Caffeine, he notes, is a “pretty stable organic molecule” and because of this, the total number of caffeine molecules in your cup is unlikely to change over the course of cooling and/or being reheated.
Allow hot coffee to cool a little, then store your brewed coffee in an airtight container in the fridge. Black coffee will keep for one to two weeks in a chilled environment, although the flavor will break down as the days go by. Coffee beans shouldn't go in the fridge or freezer.
I recommend making the espresso, adding whatever sugar or flavor you want while it is still hot, chilling it in the fridge, and then adding milk to the espresso once it has been chilled or when you are looking to drink it. This will keep for a maximum of 48 hours.
Black coffee will stay fairly fresh for about four hours after brewing, but it's still safe to drink 24 hours later and can be kept in an airtight container in the fridge for up to a week. Cold brew is a great way to enjoy fresh coffee with virtually no waste. Coffee with dairy should be tossed after two hours.
You can make it last a bit longer by storing it into an airtight thermos or a lidded coffee mug that seals out the air. When stored in an airtight container with a lid, a brewed cup can stay fresh for about four hours. Cold brewed coffee has a much longer life.
It's entirely possible to heat cold brewed coffee as long as you know the effects and how to mitigate them. Identity Coffees cautions that you could experience a loss in flavor and quality while gaining bitterness. The smooth quality so prominent in cold-brewed beans can recede.
If you're wondering why does reheated coffee taste bad, it's because the chemical composition of the cold coffee is changed during the reheating process. However, reheating day-old coffee won't affect the levels of caffeine present, which is a bonus as that means the coffee will give you the same energy boost.
Caffeine does not evaporate or disappear after brewing, so even brewed coffee will retain its caffeine levels almost indefinitely.
On average, coffee will last about 24 hours inside a thermos. But for those aficionados that get serious about this stuff, you might want to use a thermometer. If your coffee temps at 140*F (60C) 5 hours after brewing, your coffee should be sufficient for another 8-9 hours.
Storage Tips
The fridge is not the place to store coffee in any form, ground or whole bean even if in an airtight container. It isn't cold enough to keep your coffee fresh, and because coffee works as a deodorizer, it will absorb all the aromas in your fridge.
One way is to take a week off from coffee every month. That's what Ashley Richmond, the founder of Momentum Habits, does. She recommends taking the first week of the month off so it's easy to remember. If that sounds too harsh, try the slower approach.