Have you ever struggled to perfectly cook pasta while vacationing in the mountains, no matter how long you let it boil? Pasta that seems underdone even after cooking longer than the package directions say it should take? If so, you’re not alone – and the reason has everything to do with altitude. At higher elevations, water boils at a lower temperature due to decreased atmospheric pressure. This means foods cooked in boiling water, like pasta, heat up more slowly. Other factors like slower evaporation also contribute to mountain pasta taking longer to cook. The result is stranded al dente seekers cursing at stubbornly crunchy noodles. So the next time your pasta fails to soften on your mountaintop getaway, take heart – it has more to do with where you are than how you’re cooking it.
1. Lower Boiling Point
The primary reason pasta takes longer to cook at higher altitudes is that water boils at a lower temperature due to decreased air pressure.
As you gain elevation in the mountains, there are fewer molecules of air pressing down per square inch. This lower air pressure causes water to require less heat in order to reach its boiling point.
As air pressure decreases with increasing altitude, the water molecules do not move as fast and collide with each other less vigorously. This means they need less thermal (heat) energy to reach the point where they escape from the liquid and form bubbles that constitute boiling.
- At sea level, water boils at 100°C (212°F). This is the temperature required for the starches in pasta to gelatinize and soften the noodles.
- But as altitude increases, the boiling point of water drops. At 5,000 feet, water boils at around 94°C (201°F). At 10,000 feet, it boils at 90°C (194°F).
Since pasta cooks in the boiling water, it will heat up more slowly the lower that boiling temperature is. This means it takes significantly longer for the pasta to absorb enough heat and moisture to become al dente.
In general, for every 1,000 feet of increased elevation, the boiling point drops by 1°C (1.8°F). So at 5,000 feet, water boils around 6°C (10°F) lower than at sea level.
Pasta cooking times can increase by 25% to 50% or more when going from sea level to elevations of 5,000 to 10,000 feet, depending on pasta shape and size.
The decrease in boiling point and corresponding slower heating of pasta as altitude increases is the primary factor contributing to mountaintop pasta taking much longer to become perfectly al dente.
2. Slower Evaporation
Another factor that contributes to pasta taking longer to cook at high altitudes is the slower rate of evaporation. While this effect is smaller than the impact of lower boiling points, it does play a role.
When water is boiling, some of it transforms from a liquid to a gas state through evaporation. This evaporation process requires heat energy, which is drawn from the remaining liquid water.
As water evaporates from the boiling pasta pot, it transfers heat to the surrounding air and carries away some of the thermal energy sustaining the boil. This evaporation helps keep the temperature of the boiling water from exceeding the boiling point too much.
However, evaporation occurs more slowly at higher altitudes due to lower air pressure and lower water vapor content in the thinner air. There are simply fewer gas molecules for the water molecules to collide and interact with as they transition to vapor.
With a reduced rate of evaporative heat loss from the boiling pot, the temperature of the water is able to remain closer to the lower boiling point for a longer period of time. While still technically “boiling,” the water is actually maintaining a lower temperature over an elongated time span.
This has two effects that contribute to slower pasta cooking:
- First, the lower overall temperature of the boiling water at altitude means the pasta heats up more gradually as it absorbs thermal energy. Since the water is boiling at a temperature like 87°C (189°F) rather than 100°C (212°F), the pasta is unable to quickly come up to its optimal gelatinization temperature range.
- Secondly, slower evaporation from the pot means less steam generation around the pasta itself. Pasta cooks not just from boiling water contacting its surface, but also from steam capturing trapped air pockets within its structure and replacing that air with hot moisture. With reduced steam production at altitude, this process is somewhat delayed.
While these evaporation-related factors play a secondary role to the decreased boiling point, they do enhance the effect of slower cooking times at higher elevations. Together, lower boiling points and reduced evaporation rates create a “double whammy” that makes achieving perfectly al dente pasta in the mountains much more difficult – unless you adjust by extending cooking times by 25% to 50% or more.
Tips for Cooking Pasta at High Altitudes
To properly cook pasta at elevations of 5,000 feet or higher, follow these recommendations:
- Increase cooking time significantly. As a starting point, add 25% to 50% more time to the cooking instructions on the pasta package. For example, if the package says to cook for 8 to 10 minutes, start with 10 to 15 minutes at 5,000 feet and up to 15 to 20 minutes at 10,000 feet.
- Check the pasta frequently. Start checking the pasta a few minutes before you think it might be done. Pasta can overcook quickly at high altitudes, so checking it often is critical.
- Taste test sooner. Start tasting smaller pieces of pasta a few minutes earlier than you normally would to get an idea of how long it will actually take to achieve the doneness you want.
- Use a timer. To ensure you don’t under or overcook the pasta, set a timer and check the pasta at regular intervals once the time is up.
- Add salt to the water.Adding 1 to 2 tablespoons of salt per 4 quarts (1 liter) of water will help the pasta absorb water faster, shortening cooking time slightly. But don’t skip increasing time overall.
- Increase the water temperature.Bringing the water to a full, rolling boil before adding the pasta can help it heat up faster. But again, still plan to increase total cook time by at least 25%.
- Use fresh water. The lower boiling point of water at high altitude means it takes longer for the water to come back to a full boil after adding cold pasta. Use fresh water for each batch.
- Stir the pasta occasionally.Gently stirring the pasta with a fork or tongs once or twice during cooking helps it heat more evenly and prevents sticking.
- Undercook the pasta at first. If you find your pasta is still too firm even after the maximum recommended time, next time undercook it slightly and toss it with sauce in a pan over low heat to soften further.
With practice and patience, these strategies will help you achieve perfectly “al dente” pasta when cooking above 5,000 feet. The tricky part is unlearning how long it “should” take at sea level!
Navigating the confounding world of high-altitude pasta cooking can be frustrating at first. But by understanding that decreased air pressure causes lower boiling points and slower heating, extending cooking times significantly, checking the pasta frequently and making minor adjustments to your cooking process, you can master the art of the perfect mountain pasta. With patience and practice, soon you’ll wonder what all the fuss was about – until you try cooking pasta at sea level again!
1. Does boiling point decrease linearly with altitude?
No, the boiling point does not decrease linearly with increasing elevation. The decrease is more rapid at first, then slows at higher altitudes.
2. How long should I increase cooking time at altitude?
In general, start by increasing pasta cooking time by 25% to 50% or more at elevations between 5,000 and 10,000 feet. But continue checking the pasta frequently and adjusting from there based on your desired doneness.
3. Will salting the water help at high altitude?
While adding salt to the cooking water can aid pasta’s absorption of water slightly, it is not enough to compensate for lower boiling points at altitude. You still must increase cooking time by at least 25% for properly cooked results.