Coffee: The Perfect Nightcap
With its high caffeine content, coffee can provide a great energy boost late at night when tiredness and fatigue often set-in. But, can you drink coffee left overnight? To answer this pressing question, it’s important to understand how coffee reacts to sitting for extended periods of time.
Coffee is hygroscopic, meaning that it naturally absorbs moisture from the air around it. The longer it rests, the more moisture it absorbs. Meanwhile, the oils in the coffee beans evaporate, taking with them some of the coffee’s flavor. As a result, coffee tasting fresh and potent the next morning can be a bit of a gamble. Additionally, bacteria and chemicals can break down the coffee during extended exposure, which could lead to a hazardous amount of bacteria or a strange taste.
So, while coffee left overnight is not necessarily harmful to consume, it is often not as flavorful or aromatic as when it was freshly brewed. Still, there is a way for those who want to enjoy a fresh cup of coffee the next morning. Refrigerating the leftover coffee can help it to retain the natural oils and from evaporating, which will help it to keep its fresh taste, minimizing the chance of any off-putting flavors. For those devoted brew-lovers, refrigerating the coffee is an absolute must.
According to Diane Burns, a food scientist at Harvard University, “Iced coffee holds its flavor longer, but it still has to be thrown away after 48 hours. Hot coffee should be discarded after 15.” It is important to understand the science behind why these time limits are in place. Bacterial growth can occur in coffee left in an open container, so it is important to discard coffee after the advised time limits to prevent food poisoning.
So, while you can drink coffee left overnight, it is not advised. Caffeine itself does not go bad and will not cause any health hazard, but the taste of the brew degenerates quickly and could lead to an off-putting, strange taste. Opt for refrigerating the coffee to minimize the chances of a bad cup.
Instant Coffee
What about instant coffee? Instant coffee absorbs moisture from the air just like regular coffee, leading to an unpleasant aftertaste. It is also important to note that some of the taste and aroma can be lost even if the instant coffee is kept in an airtight container. Therefore, it is best to discard any leftovers as soon as possible.
In addition, longer storage times of instant coffee could also lead to the breakdown of vital molecules responsible for that typical “coffee taste”. In other words, the longer instant coffee sits, the more degraded the taste is — meaning, like regular brewed coffee, instant coffee should be discarded after a few hours.
Instant coffee is a convenient quick-fix for those time crunches, but it should not be neglected due to its short shelf-life. Before serving, read the label for recommended storage times and avoid leaving it for too long — always discard unopened packages after their expiration date.
Caffeinated Tea
Caffeinated teas also contain caffeine, an alkaloid found in coffee beans and kola nuts. Most caffeinated teas are from leaves of the Camellia sinensis plant, which contain up to four milligrams of caffeine per cup. Like coffee, caffeinated tea can also be left overnight, but it does not follow the same hygroscopic rules. In fact, because of the tea leaves contained in the beverage, caffeinated tea holds its flavor better than coffee left overnight — making it perfect for a late-night indulgence.
The tea leaves also work to naturally reduce caffeine content, meaning that drinking it afterwards rather than freshly brewed can reduce some of the caffeine content. It is also important to note that teas made from red or green tea or mate leaves can turn bitter if they are left too long. To be on the safe side, it is best to discard any leftovers after 24 hours to maintain the flavor.
The perfect nightcap for those who enjoy caffeinated beverages could be found in a cup of freshly-brewed caffeinated tea. Although it should be discarded after 24 hours, its rich taste will still be present in the morning, offering a great energy boost.
Additives
Apart from the hygroscopic and flavor altering properties of coffee, one factor that could affect how long it can stay is the additives used in the coffee. The additives — from cream to sugar and more — can break down bacteria in the coffee and hence help maintain freshness for a longer period of time.
However, it is important to note that the bacteria in question can still exist and may cause food poisoning, so it is important to discard coffee left overnight no matter the additives used.
Using additives in coffee can definitely help keep the coffee fresh for a longer time, but it is important to discard coffee after 15 hours, even if additives are used. Not only to prevent potential food poisoning, but also to maintain a flavorful experience.
Cold Brew
Finally, let’s talk about cold brew coffee. Cold brew coffee is made from coffee grounds soaked in cold or room-temperature water for anywhere from 8–24 hours. This cold extraction produces a smooth and bold coffee that maintains its flavor for days after it’s brewed—so unlike regular coffee that should be refreshed every 15–24 hours, cold brew coffee can hold its flavor for up to four days.
This unique brewing process also results in a lower acidity taste, making it a good option for those sensitive to stomach acids. The extended steeping time also means that cold brew coffee can maintain 67% of its caffeine content after 24 hours, giving you an extra energy boost the next morning.
So, for those looking for a nightcap without the worry of tossing their morning cup in the garbage after 15 hours, cold brew coffee is the perfect choice. Not only does it maintain flavor for longer than regular coffee, it also allows for added control over the caffeine content.
Reheated Coffee
When it comes to reheating coffee, it is important to note that this process can destroy the flavor compounds in coffee. Reheating also removes any benefits of calorific content, meaning that reheating coffee is not ideal. Additionally, reheating can lead to bacterial growth, which is never advisable.
In short, the flavor of reheating coffee deteriorates so quickly and the potential health hazards can occur, that it is best to discard any leftovers and start fresh.
Conclusion
In summary, while drinking coffee left overnight is not hazardous to health, it should be discarded after 15 hours due to flavor-degrading compounds and a potential build-up of bacteria. Cold brew coffee is a great way to enjoy a nightcap without sacrificing flavor the next morning, as well as consistency over caffeine content. Instant coffee should also be discarded after a few hours due to its natural loss of flavor and aroma, as well as its quick expiration date. Finally, reheating coffee is not only bad for the flavor, but can also lead to bacterial growth.
