Boiling water is 212° F
Boiling water is 212° F at sea level. The liquid will have many bubbles bursting all over the surface, and a steady cloud of steam is visible. For a brief science lesson, heating water causes the water to turn to a gas, and the bubbles are the gas rising to the surface.
Altitude Effects Boiling Point
The temperature of boiling water varies based on the elevation. A decrease in atmospheric pressure causes a lower boiling point because it takes less energy for the gas to come to the surface and escape. Water at higher elevations may boil at 200° F rather than at 212° F, for example. According to FSIS, each 500 feet increase in altitude causes a drop of about 1° in the boiling point of water.Turning up the burner will not increase the temperature of the liquid. Once a liquid has reached its boiling point, the liquid changes to steam so turning up the burner will only cause the water to evaporate faster.
Altitude Effects Cooking Time
Because the liquid is cooler at higher elevations, the cooking time will need to be increased to get the food completely cooked. A recipe that states to cook for 10 minutes may take 12 or more minutes to cook. The cooking time may increase from 4 to 11 percent depending on the food.The boiling point of other liquids may vary from that of water, but the same effects caused by elevation occurs. Pressure cookers are used by many who live at high altitudes because the water can reach temperatures above 212°.
Foods that are boiled
The term boiling is sometimes misused. Few foods are actually boiled to the stage of being done. Many foods are placed in boiling water briefly before the heat is turned down including hard boiled egg. High protein foods such as meat and fish should not be boiled.
Pastas and grains
Foods frequently boiled are dry ingredients such as pasta and some grains. The dry ingredients should be put in the pot after the water is boiling. When you add room temperature ingredients, the water will stop boiling as it heats the food. This can cause the ingredients to get water-soaked before they begin to cook.
Ways to reduce the effects of adding food to boiling water:
- Using a big pot and lots of water.
- Introducing the dry food slowly to the pot and allowing it to reach boiling point between adding more.
- Another way to get the temperature up quickly is to cover the pot. Remove the lid when water returns to boiling.
Beans and Starchy Vegetables/Fruits
Unlike dry ingredients, starchy vegetables/fruits and most dry beans are started in cold water and then the food is brought to a boil. Hot water causes the starch on the surface of starchy foods (i.e. potatoes) to swell and cook rapidly. The exterior of the food is lumpy and sticky while the inside is under cooked. When the food is just tender-al Dente, drain. Do not allow these starchy foods to sit in the water or broth after finish cooking. The starchy food will continue to swell as it absorbs water.
There are exceptions to the rule. Green vegetables are placed in hot water. This makes the vegetables bright green and maintains their crunch. Watch the food as over cooking will quickly make green vegetables limp and olive green.
Steaming vs Boiling
Research has shown nutrients lost during boiling is the same as those lost when steaming vegetables.
Parboiling and Blanching
Parboiling -Briefly boiling vegetables until they begin to get tender. The vegetables are then cooked using a different method such as sauteing, stir frying, grilling etc.
Blanching -The vegetables are briefly cooked then shocked. A vegetable is shocked by removing it from the hot water then immediately plunging it into ice water to stop the cooking. This technique is used to take the bite out of onions or to make vegetables easier to peel by putting in boiling water for 30 seconds.
Other factors that may influence boiling point
Hillman notes several factors that influences boiling point.
- Salt may increase the boiling point by 1° F. This change has a barely noticeable effect on cooking times.
- Sugar-another soluble-has a noticeable effect when used in heavy sugar solutions.
- Soluble minerals found in hard water may also increase the boiling point one or two degrees.
- High humidity on stormy days will reduce the boiling point by a degree or two
James Petersen,Cooking,(Berkley;Ten Speed Press,2007).
Mark Bittman,How to Cook Everything,(Hoboken, New Jersey;John Wiley & Sons, Inc.,2008).
Harold McGee,On Food and Cooking,(New York;Scribner)
Howard Hillman,The New Kitchen Science,(New York;Houghton Mifflin company,2003).