There are so many iterations of coffee. It can be iced, flavored, or decked out by pictures expertly crafted from milk foam. But, all the bells and whistles do not compare to a freshly brewed pot of coffee served piping hot.
But, there are some occasions when life gets in the way between you and your cup of joe. Whether it is the frantic rush of a morning routine or an unexpected call, it is possible to end up with a lukewarm brew. The choice then is, to reheat or not to reheat. That is the question.
The Science Behind Coffee’s Taste
Reheating coffee in the microwave or the stovetop can be acceptable if all you want is that jolt of caffeine. The good news is that the levels of caffeine are not affected by reheating. However, sensitive palates can distinguish the difference between reheated coffee and freshly brewed ones.
According to Chris Hendon, coffee gets its flavors from its complex chemical makeup. There are about 1,000 different compounds that lead up to coffee’s distinct taste. But even within this large roster of chemicals, variables can exist.
The content is dependent on different factors. Examples are how the coffee beans were harvested and what kind of soil the coffee plant grew in. For example, if the coffee has high levels of 3-methyl butanal, then it takes on a stronger caramel flavor.
This principle about coffee is an important point because chemicals react to heat. When coffee is heated or cooled, the compounds that affect its taste and smell are altered. This is why reheating coffee is a conflicting issue for some people. Some people can taste the difference in taste caused by the temperature changes.
Aside from the actual taste of the coffee, its smell also influences how pleasant the experience is for people to consume it. The fruity aroma comes from the chemical compounds found in the beans. Researchers note that once the coffee has been heated, this distinct coffee smell rapidly declines.
Ideal Temperature of Coffee
The National Coffee Association recommends a water temperature somewhere between 195 to 205 degrees to achieve the best levels of extraction. Extraction is the process where the flavors of coffee seep out into the water.
When the water is too cold, the taste can be flat and less flavorful. On the other hand, exceeding these recommended temperatures can result in a very bitter taste. This is because the flavors from the beans are extracted too early.
If brewing coffee, the ideal process is to let the water boil then turn off the heat. Let the water rest before using it on the coffee grounds.
The ideal drinking temperature of coffee largely depends on personal preference. However, research has shown that a majority of hot coffees are served at a temperature between 180 to 185 degrees but are consumed at about 150 degrees.
The first factor that affects coffee’s taste is the temperature it is brewed. But, that is only one part of the equation. The second is how a person’s ability to taste is influenced by temperature.
In a study published in Nature, researchers discovered that food or drink that is either too hot or too cold can inhibit the tongue’s ability to taste all the flavor compounds.
Can you Reheat Coffee?
When it comes to coffee, experts observed that the cooling seems to make the drink taste take on a more acidic flavor profile. Research is scarce when it comes to this phenomenon, but it is suggested that it is caused by the coffee oxidizing when it is exposed to air.
The aroma of coffee will also not be the same. As mentioned earlier, the first pass of heat will diminish the smell and unfortunately, there is no way to bring it back.
Coffee connoisseurs generally frown at the idea of reheating coffee, but it is not always practical to brew a pot. When reheating, there are some techniques that can be utilized to minimize the flavor changes as much as possible.
First, reheat the coffee as slowly as possible until it reaches the ideal brewing temperature. Bringing it up to about 200 degrees can restore some of its original flavors.
Slow heating will lessen the occurrence of even more chemical reactions. It also lessens the risk of burning the coffee. Unlike a tepid temperature, there is no fixing a burnt-tasting cup of coffee.
The next tip is to avoid reheating coffee that also has additions like milk or sugar. These ingredients will add even more compounds to the mix that can alter the original taste. For example, milk scalds easily and can take on a sweeter flavor profile. The proteins in milk can also curdle if the temperature gets too high.
Fresh Coffee vs. Reheated Coffee - What's the Difference?
Reheating coffee does have a point of no return. All edibles are subject to the rules of food safety. Coffee that has been left out for prolonged periods can get exposed to bacteria and other pathogens. This is especially true of products like milk has been added to it.
Another consideration is mold. Mold can grow on coffee, even when it is already in liquid form. It usually looks like a thin film floating over the drink.
Reheating can kill the bacteria found in coffee, but only if is brought to a rolling boil for a few minutes. In which case, it would destroy the flavor of the coffee completely. Microwaving can kill bacteria, but it often leaves cold spots in the middle where the bacteria can survive.
Coffee is generally a stable beverage that does not go rancid. However, if the coffee is more than a day old, better toss it out and start anew. Other signs to watch out for are a weird taste and smell.
There is absolutely no contest between fresh and reheated coffee. Fresh is always better. But, reheated does not always deserve its bad rep. With proper handling, it can be a perfectly acceptable and practical solution to a lukewarm cup of joe.