Does Microwaving Coffee Change The Taste

In this brief article, we will be answering the question “does microwaving coffee change the taste”, and will tell you exactly what happens to coffee when it is microwaved, and how you can reheat coffee without compromising its taste.

Does Microwaving Coffee Change The Taste?

Yes, microwaving coffee does change its taste. This is because reheating coffee in the microwave destroys any remaining aromas left from when it was initially brewed. Reheating food and beverages changes their aroma, but studies show that compared with the traditional heating methods, microwave heating can maintain the nutritional and sensory quality of food to a higher level (1).

And aroma doesn’t only mean its smell – we’re talking about everything that grants coffee its distinct flavor; the bitter, salt, sour, and sweet. 

Reheating coffee also rearranges its chemical composition, ultimately killing its flavor and making it taste stale after a run in the microwave.

However, in a study, reheating of prepared Turkish/ Greek coffee brews to the boiling state significantly increased the content of chlorogenic acid, a beneficial bioactive compound, and caffeine when compared to the initially prepared brews. In the reheated sample (2).

Do Coffee Pots and Carafes Also Change Its Taste?

Unfortunately, yes. Any type of carafe or brewer that supplies heat to the coffee and keeps it warm –  instead of simply insulating it like a thermos to maintain its temperature – will eventually turn it bitter and metallic-tasting. 

Why Does Microwaved Coffee Taste Bitter?

Coffee contains chemical compounds that possess biological activities, including antiproliferative, antioxidant, and antimicrobial effects. These are caffeine, chlorogenic acid, diterpenes, and trigonelline and play key roles in these bioactive effects of coffee. They are sensible to temperature and oxygen and can degrade because of storage and reheating (3).

When you reheat coffee, it boosts the production of quinic and caffeic acid, which make the coffee develop a highly bitter and astringent flavor.

Prior to roasting coffee beans, their DNA consists of certain compounds and acids that are simply waiting to become bitter when heated.

Green (unroasted) coffee beans are composed of chlorogenic acids, and roasting breaks them down into quinic acid (with a flavor similar to quinine in tonic water) and caffeic acid. Roasting induces molecular changes of nonvolatile compounds, such as the conversion of chlorogenic acids into the corresponding lactones, as well as the generation of aroma active substances (4). 

Chlorogenic acid tastes astringent and bitter but quinic and caffeic acid has a highly pronounced bitter flavor. And this is why coffee is inherently bitter. But freshly brewed coffee is a delicious blend of sweetness and acidity, which is destroyed when it is microwaved. 

Does Microwaving Coffee Destroy Caffeine?

No, reheating coffee does not destroy caffeine. The change in taste is primarily because of the breakdown of acids and compounds as we’ve explained above. 

Irrespective of when the coffee was brewed, its caffeine content will not evaporate or change after microwaving; it remains the same after four minutes and four hours. 

However, water evaporation might cause the caffeine content to become slightly concentrated after reheating coffee. Caffeine is an alkaloid that is thermally stable (3).

Do All Roasts (Light, Medium, Dark) Become Bitter When Microwaved?

Yes, all roasts of coffee will turn bitter when reheated in a microwave, but to varying degrees.  However, a dark roast will have the most pronounced bitterness. 

This is because more heat is applied to coffee beans in the roasted process for a dark roast, hence it contains more bitter-tasting quinic and caffeic acids as compared to lighter roasts.

Is It Bad To Microwave Coffee?

No correlations have been found between microwaved coffee and any harmful health conditions.

However, avoid reheating coffee in plastic or plastic cups that are not microwave-safe. This will leach plastic, glue, and wax components into the heated beverage, which could lead to health problems. Another precaution is to avoid overheating. Superheating means the heating of a liquid to a temperature above its normal boiling point. The superheated state is unstable, and it can very rapidly turn into liquid at the boiling point, plus a substantial quantity of vapor. The rapid production of a substantial quantity of steam within the bulk of the water will cause it to boil vigorously and possibly to appear to explode. 

What Is The Best Way to Reheat Coffee In A Microwave?

If you don’t mind the bitter taste of microwaved coffee, here are the most appropriate and ways to heat coffee of specific brands:

  • Starbucks coffee comes in reusable containers such as glass bottles or plastic cups, but the only microwave-safe container is the ceramic mug. Microwave it for about 30 seconds to attain the appropriate temperature.
  • McDonald’s coffee cups have wax and plastic coatings along the side seams. As mentioned, these should be avoided for microwaving since the adhesive layer can melt and leach into the beverage.
  • Dunkin Donuts coffee initially came in coffee in styrofoam cups so that the drinks remained warm for longer periods. Recently, they have started using double-walled paper cups as an environment-friendly product, which is also not microwave-friendly.

What is the Best Way To Reheat Coffee?

The best way to reheat coffee is to warm it up slowly on a stove at low heat. And this doesn’t require any particular pots or containers – any heat-resistant pot will do.

Also, if the heat is mild enough, you don’t need to constantly watch over it and keep stirring. When it is heated up to your liking, simply pour it into a cup and enjoy the delicious flavors. 

But remember, the key to this method is patience. If you heat the coffee at a high temperature, you risk burning the pot as well as the beverage. So don’t rush the process.

Other suggestions include:

  • microwaving the coffee with the power set at 80 percent to reduce the amount of heat applied to it. This warms it up nicely without burning the liquid.
  • preheating the container you’ll be drinking out of. Simply heat some water and swirl it around in your coffee mug. Dump it out and pour your coffee in the mug – voila, your coffee and your mug are now warm. 

Conclusion

In this brief article, we answered the question “does microwaving coffee change the taste”, and told you exactly what happens to coffee when it is microwaved, and how you can reheat coffee without compromising its taste.

If you have any more questions or comments please let us know.

References

  1.  Wang, Jingyu, et al. Effects of reheating methods on the product quality of Hongsu chicken dish. J Food Proces Preserv, 2018, 42, e13823.
  2. Niseteo, Tena, et al. Bioactive composition and antioxidant potential of different commonly consumed coffee brews affected by their preparation technique and milk addition. Food chem, 2012, 134, 1870-1877.  
  3. Nuhu, Abdulmumin A. Bioactive micronutrients in coffee: recent analytical approaches for characterization and quantification. Int Scholar Res Not, 2014.
  4. Gigl, Michael, et al. Identification and quantitation of reaction products from quinic acid, quinic acid lactone, and chlorogenic acid with Strecker aldehydes in roasted coffee. J Agric Food Chem, 2021, 69, 1027-1038.