(Also scallion, spring onion, salad onion)

The onion, known scientifically as Allium cepa, is, on the surface, a humble brown, white or red, paper-thin skinned bulb that despite its plain looks, has an intense flavor and is a beloved part of the cuisine of almost every region of the world. The word onion comes from the Latin word unio for single, or one, because the onion plant produces a single bulb, unlike its cousin, the garlic, that produces many small bulbs. The name also describes the onion bulb when cut down the middle; it is a union (also from unio) of many separate, concentrically arranged layers.

Onions range in size, color and taste depending upon their variety. There are generally two types of large, globe-shaped onions, classified as spring/summer or storage onions. The former class includes those that are grown in warm weather climates and have characteristic mild or sweet tastes. Included in this group are the Walla Walla, Vidalia and Maui Sweet onion. Storage onions are grown in colder weather climates and, after harvesting, are dried out for a period of several months, attaining dry, crisp skins. They generally have a more pungent flavor and are usually named by their color: white, yellow or red. Spanish onions fall into this classification. In addition to these large onions, there are also smaller varieties such as the green onion, or scallion, and the pearl onion.

Taxonomically, a green onion is the same species as a common onion and a sweet onion. Or it is a different species, Allium fistulosum. Or it is a cross of the two. This definition is as clear as the distinction between green onion and scallion. It depends upon whom you ask and the purpose of the use. In the marketplace, the terms green onion and scallion generally designate slim, bulbless green onions—despite the fact that in all current American and British dictionaries the first definition for scallion is shallot. The terms spring onion and salad onion are more likely to describe a later stage of the same onions, green topped with more developed bulbs. Both the bulbless and the bulbing forms come from the same seed as common storage onions, planted in tight quarters and harvested very young.

Definitions aside, you will receive some beautiful green onions this week, as well as some bulb onions. We hope you enjoy them.

History

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 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 were an indispensable vegetable in the cuisines of many European countries during the Middle Ages and later even served as a classic healthy breakfast food. Christopher Columbus brought onions to the West Indies, and from there, their cultivation spread throughout the Western Hemisphere. Today China, India, the United States, Russian, and Spain are among the leading producers of onions.

Nutritional benefits

Onions, like garlic, are members of the Allium family, and both are rich in powerful sulfur-containing compounds that are responsible for their pungent odors and for many of their health-promoting effects. Onions are a major source of both phenols and flavonoids, phytonutrients that numerous population studies have shown are protective against both cardiovascular disease and cancer. Onions contain allyl propyl disulphide, while garlic is rich in allicin, diallyl disulphide, diallyl trisulfide and others. In addition, onions are very rich in chromium, a trace mineral that helps cells respond to insulin, plus vitamin C, and numerous flavonoids, most notably, quercitin.

Research published in the November 2004 issue of the Journal of Agricultural and Food Chemistry shows that the variety of onions you choose and the way you prepare them can make a huge difference in the amount of beneficial compounds, and the antioxidant and anti-cancer effects, they deliver. According to the study, the most pungent onions deliver many times the benefits of their milder cousins. Shallots have the most phenols, 6 times the amount found in Vidalia onion, the variety with the lowest phenolic content. Shallots also had the most antioxidant activity, followed by Western Yellow, New York Bold, Northern Red, Mexico, Empire Sweet, Western White, Peruvian Sweet, Texas 1015, Imperial Valley Sweet, and Vidalia. Western Yellow onions had the most flavonoids, 11 times the amount found in Western White, the variety with the lowest flavonoid content. For all varieties of onions, the more phenols and flavonoids they contained, the more antioxidant and anti-cancer activity they provided.

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. 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 at room temperature, away from bright light, and in a manner where they are well ventilated. To do this, either 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, can stay 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.

The remainder of cut onions should be wrapped tightly in plastic or in a sealed container and should be used 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.

Tips for Preparing Onions
The onion is famous for brining a tear or two to the eyes. The compound that causes this burn is a phytochemical known as allyl sulfate that is produced when sulfur-compounds released by the onion’s ruptured cells are exposed to air.

If cutting onions irritates your eyes, there are a few tricks that you can employ. Chill the onions for an hour or so before cutting. This will slow the activity of the enzyme that produces the allyl sulfate and is a better choice than the traditional method of cutting onion under running water. This latter process may dilute the amount of allyl sulfate, which, while it may be irritating to the eyes, is actually one of the phytochemicals most responsible for onions significant health benefits. Use a very sharp knife and always cut the onions while standing; that way your eyes will be as far away as possible. If cutting onions really makes you cry, consider wearing glasses or goggles.