The flavonoids in onion tend to be more concentrated in the outer layers of the flesh. To maximize your health benefits, peel off as little of the fleshy, edible portion as possible when removing the onion’s outermost paper layer. Even a small amount of “overpeeling” can result in unwanted loss of flavonoids. For example, a red onion can lose about 20% of its quercetin and almost 75% of its anthocyanins if it is “over-peeled.”
With their unique combination of flavonoids and sulfur-containing nutrients, the allium vegetables—such as onions—belong in your diet on a regular basis. There’s research evidence for including at least one serving of an allium vegetable—such as onions—in your meal plan every day.
The outstanding polyphenol content of onions (including their rich concentration of flavonoid polyphenols) is probably the most overlooked nutrient content of these allium vegetable. Among the flavonoids, onions also provide a particularly large amount of quercetin. Onions are a very good source of biotin. They are also a good source of manganese, vitamin B6, copper, vitamin C, dietary fiber, phosphorus, potassium, folate, and vitamin B1.
Onions, like garlic, are members of the Allium family, and both are rich in sulfur-containing compounds that are responsible for their pungent odors and for many of their health-promoting effects.Onions are an outstanding source of polyphenols, including the flavonoid polyphenols. Within this flavonoid category, onions are a standout source of quercetin.
How to Select and Store
Choose onions that are clean, well shaped, have no opening at the neck, and feature crisp, dry outer skins. Avoid those that are sprouting or have signs of mold. In addition, onions of inferior quality often have soft spots, moisture at their neck, and dark patches, which may all be indications of decay. As conventionally grown onions are often irradiated to prevent them from sprouting, purchase organically grown varieties whenever possible to avoid onions that have undergone this process. When purchasing scallions, look for those that have green, fresh-looking tops that appear crisp yet tender. The base should be whitish in color for two or three inches. Avoid those that have wilted or yellowed tops.
Onions should be stored in a well ventilated space at room temperature, away from heat and bright light. With the exception of green onions, do not refrigerate onions. Place them in a wire hanging basket or a perforated bowl with a raised base so that air can circulate underneath. The length of storage varies with the type of onion. Those that are more pungent in flavor, such as yellow onions, should keep for about a month if stored properly. They will keep longer than those with a sweeter taste, such as white onions, since the compounds that confer their sharp taste help to preserve them. Scallions should be stored in a plastic bag in the refrigerator where they will keep for about one week. All onions should be stored away from potatoes, as they will absorb their moisture and ethylene gas, causing them to spoil more readily.
Store cut onions by placing in a sealed container; use them within a day or two since they tend to oxidize and lose their nutrient content rather quickly. Cooked onions will best maintain their taste in an airtight container where they can be kept for a few days; they should never be placed in a metal storage container as this may cause them to discolor. Although peeled and chopped onions can be frozen (without first being blanched), this process will cause them to lose some of their flavor.
Onions are native to Asia and the Middle East and have been cultivated for over five thousand years. Onions were highly regarded by the Egyptians. Not only did they use them as currency to pay the workers who built the pyramids, but they also placed them in the tombs of kings, such as Tutankhamen, so that they could carry these gifts bestowed with spiritual significance with them to the afterlife.
Onions have been revered throughout time not only for their culinary use, but also for their therapeutic properties. As early as the 6th century, onions were used as a medicine in India. While they were popular with the ancient Greeks and Romans, they were oftentimes dressed with extra seasonings since many people did not find them spicy enough. Yet, it was their pungency that made onions popular among poor people throughout the world who could freely use this inexpensive vegetable to spark up their meals.
Onions, chopped, cooked
|1.00 cup | 210.00 g | Calories: 92
|Vitamin K||1.05 mcg||1|
|Vitamin C||10.92 mg||15|
|Vitamin A||0.21 mcg||0|
|Vitamin E||0.04 mg|
|Vitamin B1||0.09 mg||8|
|Vitamin B2||0.05 mg||4|
|Vitamin B3||0.35 mg||2|
|Vitamin B6||0.27 mg||16|
|Lutein and Zeaxanthin||8.40 mcg|
|Omega-6 Fatty Acids||0.15 g||0|
Percent Daily Values (%DV) are for adults or children aged 4 or older, and are based on a 2,000 calorie reference diet. Your daily values may be higher or lower based on your individual needs.
Preparing and Cooking with Onions
The healthiest way of cooking Onions
Cut onions into 1/4-inch slices to cook them evenly and quickly. Let them sit for at least 5 minutes to help enhance their health-promoting benefits.
While many people love to eat onions, most dread cutting them since this process usually brings a tear or two to the eyes. The substance that causes the eyes to burn is a special gas that has been named lachrymatory factor (LF). (The full chemical name for this gas is propanthial S-oxide, and it is made from a naturally occurring compound in onion called 1-propenyl-L-cysteine sulphoxide.)
If cutting onions irritates your eyes, there are a few tricks that you can employ. Use a very sharp knife and always cut the onions while standing; that way your eyes will be as far away as possible. Consider cutting onions by an open window. If cutting onions really makes you cry, consider wearing glasses or goggles. Chill the onions for an hour or so before cutting; this practice can slow down the onion’s metabolism and thereby lessen the rate of LF gas production. Cutting onions under cold, running water is a method that is often used to cut back on eye irritation, but it’s a method we view as a second-best choice since some of the nutrients found in onion can be lost into the flow of water.
Related: Easy and Healthy Onion Soup
Tips for Preparing Onions
- Combine chopped onions, tomatoes, avocado, and jalapeno for an all-in-one guacamole salsa dip.
- To perk up plain rice, top with green onions (scallions) and sesame seeds.
- Healthy Sauteed chopped onions can enhance the flavor or almost any vegetable dish.
- Enjoy a classic Italian salad—sliced onions, tomatoes, and mozzarella cheese drizzled with olive oil.
The Healthiest Way of Cooking With Onions read: Recipes.