There are a couple of reasons why you want to use cold, not hot water. First, because of the higher temperatures involved, the hot water in the pipes can actually allow or encourage any gunk that's in those pipes to loosen and dissolve into the water, and you certainly don't want any pipe gunk in your cooking water. Second, root vegetables tend to be very hard, and take longer to cook, if you start with hot water, the outside of the vegetables are likely to cook a lot faster than the interior, and you don't want that either. Uniform cooking rates are better.
Depending on the vegetables, you can steam them or Blanche them. (Where you put vegetables in boiling water, then put them in ice cold water)
shocking.
Blanching works by quickly cooking the food and then quickly stopping the cooking progress. This is usually stopped using ice water.
Fruit and vegetables should always be washed under a running cold water tap before eating or cooking.
Parboiling is typically done with boiling water, which is hot. The process involves partially cooking food, usually vegetables or grains, by immersing them in boiling water for a short period before further cooking. This method helps to enhance the texture and flavor while reducing overall cooking time.
If you are looking at decreasing cooking time you would use cold water. Thermal exchange causes the water temperature to have a drastic increase. If you are just cooking the egg then it doesn't really matter.
start out in cold water so that the potato isn't "shocked" and all of the potatoes get the same cooking time.
Cooking is made generally with hot water.
just very cold water,just ice cold water,also needed when making pie crusts,cold temperature helps with the consistency
When steaming greens, their prime texture is often reached and quickly destroyed into mush, we cold-shock vegetables to hault the cooking process. and add extra color.
The boiling water is to cook the vegetables. It also serves to sterilize them and make sure no germs are passed on. The ice water afterwards helps to maintain the bright colors and stop the cooking so they don't get too soggy. In some cases, especially with fruits, it is a way to make it easier to peel off the skin of the fruits. Peaches and tomatoes are much easier to skin when this is done.
To prevent fresh pasta from sticking together after cooking, make sure to stir it frequently while cooking, add a little oil to the cooking water, and rinse the pasta with cold water after cooking.