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Reheating Coffee: Everything You Need to Know

If you're wondering if you can reheat your coffee without the overly bitter taste, or how to reheat coffee in the microwave without changing the taste, this post is for you.

We've all had times when our coffee gets cold. Maybe you were in a rush and didn't have time to finish, or maybe you made some extra coffee before. Is it OK to reheat coffee?

In general, you should avoid #coffee as it becomes more bitter with additional heat. However, if you use coffee at a low temperature and only hot down to 60 °C (140 °F), you can make the coffee hot and highly drinkable again.

Coffee is a complex substance with a good amount of science behind coffee and heat. We looked at the research behind this and how reheating can make your coffee more bitter unless you follow certain steps.

The Science Behind Heat and Coffee

Before we move on to reheating coffee, we need to understand the chemistry behind heat and coffee. Heat changes the composition of green coffee beans during the roasting and brewing process, which affects the flavor and bitterness of the coffee.

A green coffee bean has more than 1000 different compounds. Compounds are generally of two types. The first are non-volatile compounds containing caffeine and chlorogenic acids. Second, they are volatile compounds that contribute to the flavor and aroma notes that make great coffee.

The heat breaks down the non-volatile compounds during the roasting process and effectively creates many of the volatile compounds we love in our coffee. The problem is that volatile compounds, say, are volatile and tend to burn the longer the coffee is roasted.

So the longer the coffee is roasted, the more those unique flavor notes tend to be lost in favor of other flavors. Therefore, light roasts have a more pronounced taste and aroma from volatile compounds, while dark roasts have a roasted and burnt flavor.

The brewing of coffee leads to another change in the chemical composition of the coffee. Hot water draws certain coffee compounds into our cup, and good coffee brewing is all about removing the good compounds (i.e. volatile compounds) while avoiding others.

Too much heat removes compounds we don't want, such as chlorogenic acids, so the proper water temperature is very important for making coffee.

These chlorogenic acids cause a bitter taste in our coffee. Some chlorogenic acids decompose during roasting or turn into delicious sugars during the Maillard reaction. However, most chlorogenic acid remains in the bean and is extracted during brewing. With sufficient heat, chlorogenic acids break down into caffeic acid, which is directly responsible for the bitter or astringent taste in coffee.

But What Does This Have To Do With Reheating Coffee?

The science behind roasting and brewing your original cup still holds true when you reheat the coffee. When you reheat the cooled coffee, you effectively have another round of brewing without the fresh grounds.

In other words, the beans you use to make your coffee contain acids, compounds, and oils. During the original brewing, these were released in a calculated way to account for the taste we all look forward to when drinking coffee.

During the reheating process, oils, acids, and compounds are exposed to an additional form of brewing. This extension can release oils and acids that cause a bitter taste, such as caffeic acid. Reheating the coffee also burns away the volatile compounds that contribute most of the flavor, with more chlorogenic acid converted to caffeic acids, which taste bitter.

The added heat causes the better things to go away, while the bitter things become more common. That's why an old pot of coffee tastes so bad after being on the stove for hours.

For all these reasons, you should avoid reheating the coffee. Applying more heat to the brewed coffee will only make it more bitter and affect the taste. Even letting the coffee cool naturally will make it taste worse.

How to Warm Coffee Properly

Although we recommend that you always brew coffee with the freshest beans and consume immediately, we know that this is not always possible. Some situations may require reheating your morning cup.

To properly reheat coffee, use the minimum heat required to bring the coffee to a warm temperature. This avoids adverse chemical reactions as much as possible.

Use a low temperature to heat the coffee evenly. Also, warm the coffee to a modest temperature of 60°C (140°F). This temperature is lower than a freshly brewed coffee, which usually comes out around 75°C (167°F). Low temperature attenuates most of the chemical changes, and we've even found that most people prefer a temperature of 60°C (140°F) and brings out the best flavor in coffee.

Two special ways to reheat coffee while properly preserving taste and aroma.

Reheating Coffee on the Stove

If you notice that your coffee is getting cold, don't be upset. One of the best ways to restore it is to reheat it on the stove. Bacidly follow these simple steps:

Pour the coffee from the mug into a small saucepan.

Heat until the coffee has evaporated. Do not let the coffee boil.

Then pour your coffee back into a glass (preferably not porcelain, as the newly heated coffee cup may be too hot to hold).

This way of warming your drink will keep the compounds and fats intact and reduce the acids from making your drink bitter. However, you need to perform this method as soon as possible. If you try to reheat your coffee after it has been brewed for an hour and a half and sat in a glass, you will likely end up with an unpleasant aftertaste.

Reheating Coffee in the Microwave

Using a microwave to reheat your coffee is another option. But going this route will require you to change a few settings on your machine to maintain the quality of your brew.

To best reheat your coffee in the microwave, follow these steps:

Set your microwave power to 80% (or medium)

Place your microwave-safe mug inside

Warm your coffee in 30 second intervals, checking the temperature after each cycle.

Going in 30-second intervals will allow you to reduce the chance of your beverage burning. While reducing the strength also reduces the beverage's rancidity conditions, it's still possible for this to happen.

To combat the bitter taste that can come from microwave heating, many people mask the taste by adding cream, milk, or half-and-half later.

Do's and Don'ts When Reheating Coffee

While there are certain things you should do when reheating a cup of coffee that has cooled down, there are also certain things you shouldn't do. These include:

Avoid Reheating Dairy Products

If you add milk or cream to sweeten your coffee after brewing, it would be unwise to reheat your beverage. Dairy products and cream add different ingredients to a beverage and can coagulate easily. Additionally, heating dairy products can add scalding and an unpleasant aftertaste to your coffee.

Another note to note is that the amount of time your cup of coffee will still taste good is reduced when you add milk or cream. Dairy products often bounce back when exposed to hot conditions outside the refrigerator. Therefore, reheating or drinking dairy products that have been out for a long time can cause digestive or health problems.

Don't Microwave at Full Power

When you use a microwave, it does its job fast. This action does not change when reheating the coffee. Therefore, keeping your microwave at full power while heating your beverage will cause it to heat up faster than you would like.

Your coffee can burn if it gets too hot too quickly. If you've ever had burnt coffee, you know why it's not a pleasant aftertaste and should be avoided at all costs.

Do Not Use an Extended Heater on Your Machine

Many coffee makers come with a setting that keeps your brewed coffee warm for several hours after you start brewing. However, even if you find it useful or appropriate, it is not a good choice.

When your coffee is heated for that long, it loses its flavor integrity. Just like when deciding which bean to grind based on a fast or slow flow, heating your brewed coffee for that long gives more access to the water flow and increases the likelihood of bitterness.

Although the brewing process does not involve entering the coffee grounds directly into the coffee pot, some particles get into the coffee. You can often see this when you get to the bottom of the pan or use a French press.

These particles are what continues to brew when you leave your machine hot. Therefore, prolonged brewing will bring out the bitterness and scalding flavors you want to avoid.

How to Avoid Cold Coffee

Other than using the heating mechanism in your coffee maker or constantly reheating your beverage, some options can keep your beverage fresh without worrying about affecting the taste.

Brew Small Batches

There are now many ways to brew coffee that don't require you to make an entire pot at once. There are many options for creating single-serving drinks, whether in a drip machine, single cup, French press, or pour.

Doing this gives you access to fresh coffee without fear that the extra coffee left in the pot will lose its excellent taste. What's more, if you decide you want another cup, you can always make another of the same size and quantity and have another hot, delicious coffee mug instantly!

Thermal Cups

This suggestion may seem mind-blowing, but many people don't think about it when drinking coffee at home. Most households have some type of travel coffee cup, but they choose to reserve it for the sole purpose of being on the go and mobile. For this reason, people do not think of using it while consuming coffee at home.

However, using a thermal glass at home will keep your drink hot longer than a standard glass. The insulation on these cup styles keeps the heat inside without worrying about over-brewing.

amount. Because the glass itself is not a source of heat, you don't have to worry about particles causing bitterness in your drink.

Switch to Iced Coffee

While some people are not fans of cold coffee, there are plenty of coffee drinkers who just can't give up their iced coffee. That's why iced coffee, cold brew, and frappuccino are growing in popularity.

The nice thing about iced coffee is that you don't have to worry about the drink getting cold - because it already is! Additionally, the addition of ice keeps it in the same state for a while, unless of course you are in the middle of summer.

While iced coffee isn't everyone's favorite, you and your favorite barista can often make it in the same flavor styles as hot coffee. If you find yourself constantly needing to reheat coffee, you may want to consider trying iced coffee. You can surprise and like yourself!


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