The steaming versus pressure cooker debate yields two winners, since both methods preserve their vegetables’ maximum nutritional benefits and color intensity, cut cooking times considerably, and require little attention from a cook other than setting the process in motion. While both techniques cook by steaming, the main difference between the two is how long the process takes. Pressure cookers use high pressure water vapor at temperatures up to 250 degrees Fahrenheit to accelerate cooking, whereas all conventional steamers cook at 212 degrees, water’s boiling point.
How Steaming and Pressure Cooking Work
Just as water boils below its normal boiling point in the low-pressure environment of a mountaintop, for example, it exceeds boiling point in the sealed surroundings of a pressure cooker, with the added bonus of forcing moisture into the food. The fastest cooking times for pressure cookers are those which maintain a pressure of 15psi. Those that operate at a lower pressure will involve longer cooking times. For example, a cooker at 12 psi will typically require 20 percent longer cooking times. Steamers, on the other hand, cook at a uniform temperature whether they are stove-top or electric.
Pressure Cooking Advantages
A pressure cooker can be up to ten times faster than other cooking methods. At high pressure, cooking times can range from around one minute for leafy vegetables such as cabbage, spinach and greens, through a couple of minutes for winter and spring vegetables such as carrots, peas and broccoli, up to 10 minutes for tubers and root vegetables such as beets and large potatoes. However, pressure cooking is a fairly aggressive method that can be rough on delicate vegetables. Place the vegetables in a steamer basket on top of a trivet and add 1/2 cup for vegetables with short cooking times, doubling the water level for those that cook for longer than five minutes.
Cooking vegetables in a steamer allows a chef time to simultaneously prepare a main protein, such as a chop or steak, which would be harder to achieve with a pressure cooker. Steam the vegetables either by placing them in a wire sieve or rack over boiling water and covering with a lid, or by using a dedicated steamer that heats water with an element, sending the vapor up through stacked plastic tiers. Chopping the vegetables before steaming can decrease the cooking time by increasing their surface area. Steaming times are not drastically different to pressure cooker times for leafy brassicas, which are done within five minutes, but larger tubers and roots will take considerably longer, sometimes up to half an hour.
With both steamers and pressure cookers, take care when removing the lid at the end of cooking, as the steam can scald exposed skin. For vegetables with short cooking times in a pressure cooker, the secret is to work quickly and not to leave them in the cooker longer than necessary to avoid overcooking. Leave greens too long, for example, and they will lose some of their color. Running the pressure cooker under cold water before you open it helps equalize the pressure quickly, allowing you to remove the basket from inside and serve.