Since I wrote about my new favorite kitchen appliance, the Instant Pot pressure cooker, I’ve gotten a lot of comments and questions about if pressure cooking is a healthy way to cook food or if it destroys nutrients.
It is certainly a logical and valid question… in fact it was the question that kept me from trying a pressure cooker for years until I finally decided to research it, and what I found was fascinating.
Growing up, I considered a pressure cooker an antiquated kitchen tool that elderly relatives used and that was most useful for canning. Some pressure cookers can double as a canner, which is probably why my elderly relatives used their pressure cooker more than those in my generation, but it turns out I had missed out on a lot of important points in my quick judgement!
How Does a Pressure Cooker Work?
A pressure cooker is a pressurized (of course) pot that cooks food using a combination of heat and steam. While it would seem that high heat is required, the steam and pressure actually provide much of the cooking power. A pressure cooker has a valve that seals in the steam, creating a high-pressure environment. This is beneficial because it increases the boiling point of the water or liquid in the pot and forces moisture into the food in the form of steam. Both of these help the food cook much more quickly.
How does this work?
Consider this- water boils at a lower temperature at higher altitudes. This is because the lack of pressure allows the water to boil at a lower temperature. You may have noticed special high-altitude cooking instructions on certain recipes and this is partially why. The lower the temperature at which water boils, the faster foods start to dry out and the more difficult it can be to cook. This is also why it takes longer to cook food at higher altitude.
Pressure cooking essentially does the opposite of altitude, it increases the boiling point of water and decreases the cooking time. Since steam can’t escape from the pressure cooker, you avoid water-loss and are able to cook foods without losing heat.
One big advantage of a pressure cooker is that it can cook foods much more quickly and energy efficiently than other methods like stove top, the oven, or even a slow-cooker.
Does Pressure Cooking Use Really High Heat?
This is where some of the confusion starts to come in. Many people assume that since pressure cooking cuts down the cook time so dramatically, it must use a much higher heat. This isn’t the case at all.
As described above, the shortened cooking time is a product of the increased pressure, not increased temperature at all. When researching, the highest recorded boiling point of water in a pressure cooker I could find was 250 degrees. That is still lower than the temperature that most foods are prepared at in the oven or stove top and about the same as a slow-cooker.
In other words, a pressure cooker may cook foods at a lower temperature than most other cooking methods, utilizing the pressure to improve cooking time and efficiency.
Does a Pressure Cooker Destroy Nutrients?
I completely understand this question, as I had the same one. At first glance, the idea of cooking foods more quickly seems too good to be true and it just seems logical that there is a downside, such as a loss of nutrients.
Fortunately, in researching this question, I found that the reverse is actually true!
Readers have asked if a pressure cooker uses high heat (see above) and if this creates the similar negative effects of high-heat methods like grilling and broiling. Again, it makes sense until we delve into the science of heat and pressure and understand that the increased pressure is what creates the faster cooking environment, not higher heat.
To reiterate, pressure cookers actually cook at a lower temperature than most other methods (steaming, roasting, etc.) but do it more efficiently. All cooking methods reduce nutrients to some degree, but I was surprised how much of a difference the cooking method could make!
In fact, a 1995 study found that pressure cooking preserved nutrients in food more than other cooking methods. Another study measured levels of Vitamin C and B-Vitamins in food and found these levels of vitamin retention (the amount remaining in food after cooking):
- Boiling reduced nutrients the most with a range of 40-75% retained (up to a 60% loss of nutrients!)
- Roasting and steaming preserved up to 90% of nutrients (but in some measurements, almost half of nutrients were lost!)
- Pressure cooking did the best job at preserving nutrients with a 90-95% retention rate
This makes sense when you think about it. Since pressure cooking doesn’t require a much higher temperature and shortens the cooking time, there is less time for nutrient loss. For this reason, pressure cooking may actually preserve nutrients better than other methods of cooking.
There are a couple of notable exceptions to this rule:
Pressure cooking does seem to deactivate certain properties in food like phytic acid. I explained in this post about traditional preparation methods for grains how reducing phytic acid and lectins makes the nutrients in foods like grains and beans more absorbable and less likely to irritate the digestive system. Pressure cooking seems to do a better job of deactivating these substances than other cooking methods.
An Important Caveat
There have been conflicting studies that showed that higher levels of nutrients were lost with pressure cooking, but follow up research revealed that most of the nutrients were actually just transferred to the cooking liquid.
For this reason, I make a conscious effort to use only as much cooking liquid as is needed when using a pressure cooker and to re-use the liquid in the meal by making a gravy, drinkable broth or sauce of some kind.
What Can You Cook?
I’ve personally only experimented with roasts, broth, meats, soups, stews, vegetables and rice in the pressure cooker (this is the one I use), but there are instructions and recipes for cooking virtually everything in a pressure cooker (including cheesecake and hard-boiled eggs!).
Many people love the ability to cook rice or beans in under an hour in a pressure cooker but I love that I can prepare a roast in under an hour!
Pressure Cooking: Bottom Line
Like any method of cooking, pressure cooking does destroy some of the nutrients in food, but it actually preserves more than any other cooking method.
With newer electric pressure cookers (like the Instant Pot), pressure cooking is a convenient and healthy way to get food on the table for your family more quickly and easily while still preserving the nutrients in your food.
Do you use a pressure cooker? What is your favorite way to use it?