What would a recipe be like if we didn’t have onions? The distinctive pungent smell and taste of onions round out the flavors of almost any cuisine. For centuries, the onion has added value to our cuisine and has also been thought to have therapeutic properties.
The word onion comes from the Latin word unio for “only” or “one” because the onion produces only one bulb. The name also suggests the union of the many separate concentrically arranged layers of the onion. Onions are native to Asia and the Middle East and are believed to have been cultivated for over five thousand years; they were highly prized by the ancient Egyptians. Often the ancient Egyptians used them as currency to pay the workers who built the pyramids, and they also placed them in the tombs of the kings (Tutankhamen) so that the kings could carry them as gifts in the afterlife. In India, in the 6th century, onions were used as medicine. The ancient Greeks and Romans often dressed onions with additional seasonings in their cooking because they didn’t find them spicy enough. Many European countries during the Middle Ages served onions as a classic healthy breakfast. It should be noted that Christopher Columbus brought onions to the West Indies and from there spread their cultivation throughout the Western Hemisphere. Today the main onion producers are China, the United States, Russia and Spain, among others.
Onions are available in fresh, frozen, canned, and dried forms. They can be used in almost any type of food, cooked, in fresh salads or as a garnish, and they are usually chopped or sliced. Onions are primarily used as an accompaniment to a main dish and are rarely eaten alone. There are many different types of onions ranging from hot and spicy to mild and sweet.
Depending on the variety, onions vary in size, color, and flavor. Generally, there are two types of large balloon-shaped onions, classified as spring / summer or storage onions. The spring / summer class includes onions that are grown in warm climates and have characteristic mild or sweet flavors. This group includes the Maui sweet onion (in the April-June season), Vidalia (in the May-June season), and Walla Walla (in the July-August season). Storage onions are grown in cooler climates and can be dried after harvest for a period of several months. They generally have a spicier flavor and are named for their color: white, yellow, or red. Spanish onions are classified as storage onions. There are also smaller varieties of onions, such as green onion (also called chives) and pearl onions.
Onions are members of the Allium family and are rich in powerful sulfur-containing compounds that are responsible for their pungent odors and many beneficial health effects. When an onion is cut, the cells break down, allowing enzymes called alliinases to break down sulfides and generate sulfenic acids (amino acid sulfoxides). Sulfenic acids are unstable and decompose to produce a gas called syno-propanetial-S-oxide. This gas then reaches the eye and reacts with the water in the eye to form a dilute sulfuric acid solution that irritates the nerve endings in the eye. Your eye then produces tears to dilute and remove the irritating substance. This is what makes your eyes itch and water when you cut onions.
Eye irritation can be reduced by supplying a large amount of water to the reaction, which prevents the gas from reaching the eyes. That is why it is believed that it is useful to cut the onions under running water or submerge them in a container of water. It can also be helpful to rinse the onion and leave it wet while you cut it. Other tips to help reduce eye irritation are to freeze the onions, which prevents the enzymes from activating, limiting the amount of gas that is generated. Also, using a very sharp knife when cutting will limit cell damage, thus reducing the amount of enzymes released. The lemon will help eliminate the characteristic smell of the onion.
As mentioned above, onions are believed to produce many health benefits. Onions are a good source of chromium, the mineral component of glucose tolerance factor, a molecule that helps cells respond to insulin. Clinical studies in diabetes have shown that the chromium produced by onions can lower fasting blood glucose levels, improve glucose tolerance, lower insulin levels, and lower total cholesterol and triglyceride levels, as well as increase good HDL cholesterol levels.
One cup of raw onion contains more than 20% of the daily value for chromium. Since chromium levels are lowered by consumption of refined sugars, white flour products, and lack of exercise, marginal chromium deficiency is common in the United States.
A case-control study of southern European populations suggests that making onions and garlic a staple in your diet can greatly reduce your risk of several common cancers. Eating onions two or more times a week is associated with a significantly reduced risk of developing colon cancer. Additionally, regular consumption of onions has been shown to reduce high cholesterol levels and high blood pressure, both of which help prevent atherosclerosis and diabetic heart disease, and reduce the risk of heart attack or stroke.
Onions can also help maintain healthy bones. A recently identified compound in onions, gamma-L-glutamyl-trans-S-1-propenyl-cysteine sulfoxide (GPCS) inhibits the activity of osteoclasts (the cells that break down bone). This can be especially beneficial for women who are at higher risk for osteoporosis as they go through menopause.
Other potential health benefits of onions include various anti-inflammatory agents that reduce the severity of symptoms associated with the pain and swelling of osteo-rheumatoid arthritis, the allergic inflammatory response of asthma, and respiratory congestion associated with the common cold. Additionally, quercithin and other flavonoids found in onions work with vitamin C to help kill harmful bacteria and are helpful when added to soups and stews during cold and flu season.
In many parts of the underdeveloped world, onions are also helpful in curing blisters and boils. Onion extract (Mederma) is used in the United States in the treatment of topical scars.
When choosing onions, choose onions that are clean, have no neck opening, and have a crisp, dry outer skin. Avoid onions that have sprouted, have signs of mold, or have soft spots, damp neck, and dark spots that may indicate signs of decay. When choosing chives, choose those with a green, fresh-looking top that is crisp and tender. They should be white in 2-3 “along the bottom. Avoid chives that appear wilted or have a yellowish top.
Store onions at room temperature, away from bright light, and in a well-ventilated area. Ideally, hang them in a wire basket or perforated container for ventilation. Onions that have a spicier flavor, such as yellow onions, can be stored for longer periods than the sweeter variety of onions, such as white onions. Chives should be stored in a plastic bag in the refrigerator and will keep well for about a week. Store all onions away from potatoes as onions will absorb moisture from potatoes and make them go bad more easily. Cut onions should be wrapped tightly in plastic wrap or sealed in a container, and should be used within a couple of days as they tend to rust and lose their nutritional value quickly. To keep the best flavor of cooked onions, they should be stored in an airtight container and used within a few days. Never put cooked onions in a metal container, as this will cause discoloration. Peeled and chopped onions can be frozen raw, but this can cause them to lose some of their flavor.
Onions can be eaten raw or cooked in almost any way imaginable: roasted, boiled, baked, creamed, fried, fried, or pickled. They are excellent in soups, stews and combined with meats and vegetables. They add a versatility to your dishes that is hard to beat.