Because there is less atmospheric pressure at high altitudes and the air is thinner, water boils at a lower temperature. This means that it can be impossible to cook food at the correct temperature and that the water tends to evaporate very quickly.
Whether you live at a high altitude or sea level, the boiling point of a pressure cooker remains fairly constant. It means that you can prepare beans without presoaking, roast cuts of meat, create casseroles and make anything you want in a fraction of the time of conventional cooking.
Although steam engines and machinery are now largely redundant, it is a marvel that the pressure cooker which was developed using the same technology in the 17th century is still in daily use today. You can greatly increase the boiling point of water by boiling it in a pressure cooker, although that may not be what you had in mind.
Because the boiling point of water increases as the pressure increases, the pressure built up inside the cooker allows the liquid in the pot to rise to a higher temperature before boiling thus cooking the food faster than usual. At 15 psi (the highest rated home kitchen pressure cooker) the boiling temperature of water is 250 degrees F.
Technically, it can turn to steam, but the water itself can not become hotter than its boiling point. If the questioner meant the boiling point at normal atmospheric pressure then you could make it boil at a higher temperature by heating it in a pressure vessel with a release valve, such as in an old-fashioned pressure cooker.
The origins of the pressure cooker can be traced to a 17th-century French physicist and mathematician named Denis Pain. Pain, who shared notes with such legendary brains as Christian Huygens, Gottfried Leibniz, and Robert Boyle, is best known for his 1679 invention of the “steam digester,” the precursor to both the pressure cooker and the steam engine.
As food and water heated up, the vessel trapped steam, raising the pot's internal pressure. Pain’s initial designs didn’t include any pressure -release mechanism, which resulted in various explosions early on.
Fortunately, Pain subsequently invented a steam-release valve to keep such accidents from happening. Some cookers don’t even release any steam while cooking; instead, they have an indicator that displays the pressure level.
View of the locking pin on a Seville Fast Slow Pro, an example of the safety features commonly found on third-generation pressure cooker models. As the US entered World War II, the government promoted self-sufficiency programs, which encouraged canning home-grown produce.
After the war, demand for pressure cookers was at an all-time high, precipitating a boom in production. Manufacturers began pumping out pressure cookers, but at the expense of materials, construction, and overall safety.
For instance, models from the '50s had a single, poorly constructed weighted valve that easily clogged with debris. As pressure built to an extreme, the gasket would blow, and water or steam would spew from the top; in some cases, the lid would just fly right off.
Fortunately, manufacturing and design practices have improved considerably, and today’s pressure cookers feature several fail-safe mechanisms to ensure safety, such as multiple valves, dual pressure regulators, and spring-loaded lid locks. A pressure cooker is a sealed chamber that traps the steam generated as its contents are heated.
As steam builds, pressure increases, driving the boiling point of water past 212 °F. In general, this higher temperature shortens cooking times and, due to a lack of evaporation, extracts flavor more efficiently from foods.
The Science of Pressure Cookers Time for a quick high school chemistry refresher: The pressure cooker can be best explained by the “ideal gas law” (or “general gas equation”), which describes the behavior of most gases under most conditions. We can explain this increase in pressure another way, too: As the system heats up, there is more energy supplied to molecules of water vapor, which causes them to bounce around and collide randomly both with each other and against the walls of the container.
The force of these collisions against the walls is one definition of pressure, based on the “kinetic model of gases.” Consider, for a moment, a pressure cooker containing water and chicken bones for making stock.
In the absence of a valve, the water would continue to heat up, building pressure indefinitely. We see this in the form of steam escaping slightly, making the pressure -regulating valve rattle as our chicken stock cooks.
For newer, third-generation electric models, the cooker detects both pressure and temperature and regulates the amount of heat supplied by the heating element, so you don’t see much steam escaping or hear much rattling. What It All Boils Down To Practically speaking, what all that science amounts to is this: In a sealed pressure cooker, the boiling point of water goes up as pressure increases.
And, because the vessel is sealed, it also limits evaporation of critical volatile flavor and aroma compounds. An added plus: the contents of a pressure cooker go relatively undisturbed, since the liquid never effectively boils.
You might be aware that general cooking times and temperatures for certain recipes differ in places like Denver, CO, or high up in the Andes. In this case, the boiling point of water in a sealed chamber cooking at high pressure will be 244.8 °F, almost 6 degrees lower than the same system at sea level.
Here in America, you have a greater choice to make when it comes to pressure cookers: electric or stove top? Natural release involves taking the cooker off heat and allowing the temperature to gradually decrease until the spring-loaded lock disengages.
Quick release, as the name implies, involves removing the weighted juggler or pressing a button to allow steam inside the cooker to escape. Doing so allows you to stop the cooking immediately, but it also means that the contents of the pressure cooker will boil vigorously.
Kenji takes advantage of that boiling to effectively blend his pressure cooker split pea soup without using a blender. On the other hand, this method doesn’t cause the contents to vigorously boil, which might be desirable for a given recipe.
As the writer Andrew Smith once said, “People fear what they don’t understand (and anything that might blow up in their faces). “*** Hopefully this article has convinced you a pressure cooker won’t blow up in your face, and given you some useful information about how they operate and why they deserve a place in your kitchen.
As human beings, we need to eat to survive, and with the modern-day convenience of packaged foods at grocery stores, as well as sprawling restaurants and eateries, we often don’t really need to know how to cook in order to keep ourselves fed. When growing up, you might not even tinker with cooking until you leave home for college or start an independent career.
Upon receiving this heat energy, the bonds holding the water molecules together begin to break. Although the boiling point of water being 100oC is correct, this only holds true if you are at sea level.
So, if you reach the mountainous regions of Colorado, for example, your school teacher’s lesson of 100oC as the boiling point of water becomes false! Now, the higher the boiling point of water, the more heat the food could absorb, resulting in a faster rate of cooking.
They force the water in the cooker to boil at a higher temperature by increasing the internal pressure and helping us cook delectable meals much more quickly! Now that you understand the basics of boiling and its relation with pressure, let’s take a closer look at the internal structure and function of a pressure cooker.
A pressure cooker is essentially a vessel of stainless steel or aluminum alloy. It has a lid fitted with a safety valve at the top to prevent the internal pressure from becoming greater than the vessel can bear.
A rubber ring is fixed at the junction of the vessel, which prevents the steam from leaking out. This escaping produces a whistling sound that users of pressure cookers are surely familiar with.
This also implies that the pressure inside is regulated, so there is no risk of the pressure cooker bursting. A pressure cooker is a useful domestic appliance, especially for those who like to cook his/her own food, but may not have as much free time as they would like.
If there is no hissing or whistling after the cooker has been on the stove for some time, the valve should be slightly shaken to ensure that the hole is not obstructed in some way. The valve should be slightly lifted with the help of tongs before opening the lid and allowing the steam to escape.