Does cooked coffee still have caffeine? The surprising thermal stability answer

October 15, 2025 •

4 min read

According to chemical data, caffeine has a high melting point of 235–238°C and a sublimation point of 178°C, meaning it is exceptionally stable at standard cooking temperatures and will not break down or evaporate from your cup. The simple answer to 'Does cooked coffee still have caffeine?' is yes, almost all of it remains present.

Quick Summary

Heating or reheating coffee does not destroy its caffeine content due to the molecule's high thermal stability, far exceeding water's boiling point. The perceived change in strength is typically due to the degradation of volatile flavor and aroma compounds, not the loss of caffeine.

Key Points

Caffeine's Stability: Caffeine is a thermally stable molecule with high melting and sublimation points, meaning typical cooking or reheating won't destroy it.
Flavor Compounds Degrade: The perception of 'weaker' coffee is due to the breakdown of delicate, volatile flavor and aroma compounds over time or with heat, not the caffeine.
Extraction vs. Destruction: Brewing methods involving boiling, like Turkish coffee, actually increase the initial caffeine extraction from grounds rather than removing it.
Boiling Point is Too Low: Water's boiling point (100°C) is not high enough to break down the caffeine molecule, which requires much higher temperatures.
Factors Affecting Caffeine: The total caffeine in your cup is determined by factors like bean type (Robusta vs. Arabica), roast level, grind size, and brewing time, not whether it's reheated.
Reheating Changes Taste, Not Effect: Reheating simply delivers a less aromatic, more bitter cup, but the stimulant effect from the caffeine remains intact.

The Surprising Stability of Caffeine

One of the most persistent coffee myths is that reheating or prolonged heating causes the caffeine to 'cook out.' However, from a chemical perspective, this is simply untrue. Caffeine is a thermally stable organic molecule that can withstand high temperatures without decomposing. The key lies in its boiling and sublimation points, which are significantly higher than the boiling point of water.

Caffeine's sublimation point is approximately 178°C (352°F), the temperature at which it can turn directly from a solid into a gas.
Its melting point is even higher, around 235°C (455°F).
In comparison, water boils at 100°C (212°F). The temperature of your brewed coffee, even if boiled for an extended period, will not come close to the heat required to alter the caffeine molecule's structure or cause it to evaporate.

This is a stark contrast to a substance like alcohol, which has a much lower boiling point and can be cooked out of a liquid relatively easily. For caffeine, the heat simply doesn't pack enough punch to do any damage.

The Real Culprit: Why Reheated Coffee Tastes Different

If the caffeine is still there, why does that second or third cup of reheated coffee taste so flat or bitter? The answer lies in the hundreds of other chemical compounds present in coffee, known as volatile aromatic compounds.

Unlike caffeine, these compounds are not stable at high temperatures and degrade or evaporate rapidly when exposed to heat and oxygen. When you first brew a cup, these delicate compounds provide the rich, complex aromas and flavors we love. When you let the coffee sit for a while, especially on a heating plate or when reheated, these volatile compounds escape, leaving behind the more stable, and often bitter, components like caffeic acids. The resulting brew is more bitter, less aromatic, and simply tastes "off," which many people mistakenly attribute to a loss of caffeine.

Extraction vs. Destruction: Brewing and Boiling

Different brewing methods involve different levels of heat and extraction time, which can influence the initial amount of caffeine extracted from the grounds. Boiling coffee, as in the case of Turkish or Cowboy coffee, can actually result in an increase in caffeine content, not a decrease. This is because the extended boiling time and direct immersion method lead to a more complete extraction of soluble compounds, including caffeine, from the coffee grounds. Boiling is a powerful extraction tool, not a decaffeination tool.

Factors Influencing Your Coffee's Caffeine Content

While heat exposure during reheating won't destroy caffeine, several other factors can influence the final caffeine content of your cup. These variables explain why one cup can feel much stronger than another, even with the same beans.

Bean Type: Robusta beans naturally contain nearly twice as much caffeine as Arabica beans.
Roast Level: Lighter roasts retain slightly more caffeine by weight than darker roasts because less mass is lost during roasting. However, this difference is minimal.
Grind Size: A finer grind provides more surface area, allowing hot water to extract more caffeine more quickly. This is why espresso, with its fine grind, is so concentrated.
Brewing Time and Temperature: Longer brewing times, like in a cold brew or a French press allowed to steep, can result in higher caffeine extraction. Higher water temperatures also increase extraction speed.

Comparison of Brewing Methods


Feature	Drip/Filter Coffee	French Press	Espresso	Turkish Coffee
Preparation	Hot water drips through ground coffee and a filter.	Coarse grounds steeped in hot water, then pressed.	Hot, pressurized water forced through a fine, compacted 'puck'.	Fine grounds, water, and often sugar boiled together.
Extraction	Long extraction time, lower concentration.	Full immersion, medium extraction time.	Very short, high-pressure extraction.	Prolonged boiling, maximum extraction.
Caffeine per oz	~10-12 mg.	Higher than drip, depends on steep time.	~63 mg.	Very high concentration.
Flavor Profile	Clean, lighter body, less bitter notes.	Rich, full-bodied, some sediment.	Bold, intense, often with crema.	Strong, often sweet, with a thick layer of grounds.
Effect on Caffeine	No change after initial brew.	No change after initial brew.	No change after initial brew.	Boiling extracts caffeine more effectively, no destruction.

Conclusion

The science is clear: cooking or reheating coffee does not destroy or remove its caffeine. The caffeine molecule is robust and thermally stable, surviving temperatures far beyond the boiling point of water. The bitterness and loss of aroma often experienced with older or reheated coffee are due to the degradation of more delicate flavor compounds, not a reduction in stimulant properties. To get the most flavorful experience, it's best to enjoy your coffee fresh. But if you're chasing that caffeine kick, know that your reheated cup still has all the power it did when it was first brewed.

For further reading on the chemical properties of caffeine, consider this research overview from ScienceDirect Topics.

Frequently Asked Questions

The stale, bitter taste comes from the breakdown of delicate, volatile compounds responsible for coffee's aroma and flavor. These compounds degrade much faster with heat and exposure to oxygen than the stable caffeine molecule.

No, boiling coffee does not destroy the caffeine. Caffeine is stable at the boiling point of water (100°C). In fact, boiling can be a very effective way to extract more caffeine from the grounds, as seen with methods like Turkish coffee.

No, caffeine does not evaporate. It has a high sublimation temperature (178°C), far above room temperature. While the flavor will certainly change due to oxidation, the caffeine remains in the liquid.

Reheating plain black coffee is generally safe, although it will impact the flavor. If your coffee contains milk or cream, it is not advisable to reheat it if it has been left at room temperature for more than two hours due to potential bacterial growth.

This is often a psychological effect or a misconception. The perceived "weaker" effect is often mistaken for a drop in caffeine when it is actually due to a less pleasant, degraded flavor profile.

To preserve flavor, keep your coffee warm in a thermos or vacuum flask to minimize temperature fluctuations and oxygen exposure. For the best taste, consume coffee immediately after brewing.

Using a microwave is often cited as the best method to reheat coffee, as it heats the liquid quickly, minimizing the time available for further degradation of volatile compounds.