Gastroenterologists warn against reheating coffee repeatedly, stressing that this not only affects its taste and smell, but may also change its chemical composition.
This leads to an increased likelihood of stomach irritation and heartburn, especially in people with gastrointestinal sensitivity.
Freshly brewed coffee contains beneficial compounds, most notably antioxidants such as chlorogenic acid, which is linked to heart health benefits and longevity. It also contains natural acids that give it its distinctive and balanced flavor.
But over time and with repeated heating, these compounds and acids begin to break down into more bitter and acidic substances, making the coffee taste harsher and causing it to lose its original flavor.
The coffee also becomes more bitter, and may leave a feeling of dryness in the mouth after drinking it.
Doctors confirm that the problem is not related to the use of the microwave itself, but rather to the duration and frequency of heating, as continuous heat gradually changes the components of the coffee.
Coffee primarily contains two components that can upset the stomach: caffeine and natural acids. Caffeine relaxes the lower esophageal sphincter, the muscle responsible for preventing stomach acid from rising, which can lead to reflux and heartburn. Simultaneously, the natural acids stimulate the stomach to produce more acid by activating a hormone known as gastrin.
For people with acid reflux or sensitive stomachs, repeatedly drinking stale or reheated coffee may worsen symptoms such as heartburn, acid regurgitation, and discomfort in the stomach and throat.
Experts point out that the danger does not lie in heating the coffee once, as most people do not have a problem with that, but rather in repeatedly heating the same cup several times, which increases the concentration of compounds that irritate the stomach.
Doctors also advise preparing small batches of coffee rather than storing it for extended periods, and storing it in airtight containers. It's also preferable to avoid reheating coffee in old, scratched, or porous cups, as this can increase the chemical reactions within the beverage.
If you experience irritation or burning after drinking reheated coffee, drinking water or eating a piece of bread or some biscuits may help relieve the symptoms, while antacids can be used if the problem persists.
Among the most prominent signs that coffee tastes spoiled due to excessive heating are: a burnt taste, excessive bitterness, and the disappearance of natural sweetness.
Experts confirm that a microwave cannot restore coffee to its original flavor, but merely heats coffee that has lost many of its properties over time, making its old and sharp taste more pronounced.
