A white onion is a type of root vegetable often recognized by the white coloration of its layers and the soft “paper” that surrounds it. It is one of the most common types of onions and has a fairly strong balance of harshness and sweetness when eaten raw. These onions can be cooked, often in some oil or butter, to caramelize the sugars within them and give them a sweeter flavor. A white onion is a fairly good source of dietary fiber and vitamin C, though cutting it can release gases that cause eye irritation.
Also called a common onion or Allium cepa, a white onion is one of the most frequently eaten types of onions available. It is, as its name suggests, generally white in color both inside and out. The outside of a white onion is surrounded by a soft layer of “paper” that is flaky and easy to remove without a knife or other utensil. Within this covering are numerous layers of “flesh” that are quite tender and can be easily separated and cut with a knife.
The flavor of a white onion is fairly mild, though it can be far too acrid for some eaters, especially when raw. It is not as sweet as some varieties, such as Spanish or Vidalia onions, though its general sweetness can vary from one sample to another. White onion is often cooked so that the sugars that are naturally found within it can caramelize, allowing it to become sweeter. When used raw, it is typically diced or otherwise cut small in size so that it can be eaten with other ingredients without being the major component in a bite of food.
White onion has a number of nutritional benefits, especially when eaten raw. Primarily, it is an excellent source of dietary fiber and vitamin C. It also contains a substantial amount of vitamin B6 and a decent amount of potassium, though other fruits and vegetables can certainly provide greater quantities.
One of the major drawbacks to cooking with white onion, however, is the volatile gas that is released by the vegetable when it is cut. Damage to cell walls within the onion causes the release of various chemicals that combine to create gas. As this gas reaches a person’s eyes, it can cause a great deal of irritation that leads to reddening and watering. Although a few different methods can be used to avoid this problem, such as cutting onions under running water, the surest way to avoid irritation is to wear goggles while cutting them.