ONION

While we may not usually think about them in this way, onions are a food of astonishing diversity. They are enjoyed in virtually all parts of the world—and so much so that you will find countries in Asia (including China and India), Southeast Asia (including Indonesia and Myanmar), the Middle East (like Turkey and Iran), South America (Brazil), and Russia all being included among the major onion-producing countries of the world. But even this level of diversity fails to tell the full story, since the top onion-consumingcountries in the world are also found in North America (the United States), Northern Africa (Libya and Algeria), and Europe (the United Kingdom and France).

Given this remarkable diversity, it is also not surprising that onions can be classified in so many different ways. In the grocery store, perhaps the most common classification system is by color. It is easy to recognize the difference between reds and yellows and whites (at least when considering the root portion of the onions (bulbs).

By contrast, the color green is typically used not to describe the root/bulb portion of the plant. Instead, "green onion" is a term usually used to refer to the stalk portion of the plant. However, this term is often used quite loosely, and it can gloss over some interesting underlying differences that can take place in the world of "green onions." Many varieties of onions that will eventually form a large bulb can be harvested quite early in the growth process so that the large bulb has not had time to form. Sometimes you will find early harvested onions being sold as "green onions." Other varieties of onions either form a very small bulb regardless of their age, or they even never form a bulb at all.

You may also find these varieties being sold in the grocery as "green onions." When varieties only form a very small bulb or no bulb at all, they are typically also described as "bunching onions" as well as "scallions." Different plant experts use this term "scallions" in different ways, however, and some experts only use the word "scallion" if the onion variety is non-bulb-forming. All of the varieties referred to above fall into the same scientific genus/species of Allium cepa. In addition, most of the varieties referred to above fall into the subspecies Allium cepa var cepa.

Two further important notes about "green onions." First, they are not always green! Apache onions, for example, are scallions with bright green stalks and very small vibrant purple/red bulb portions. Second, "green onions" also include one species not described above, namely Allium fistulosum. Green onions in this group are often referred to either as Welsh onions or Japanese bunching onions.

Shallots (Allium cepa var. ascalonicum), as you will find them in the grocery, are sometimes confused with garlic. That's because the dried bulb portion of the plant is what you typically see on display, and this variety of onion forms a cluster of small bulbs instead of one single bulb. So this dried cluster of bulbs can look like a bulb of garlic with its collection of cloves. Still, as you can see from their science name, shallots belong to the exact same genus and species of plant (Allium cepa) as all of the onions described above.

Onions can also be classified according to differences in taste. The basic dividing line here is between strong flavored and mild/sweet. As a very general rule, the softer varieties of onion are milder and sweeter in taste and the harder varieties are more pungent and strongly flavored. This distinction between strong/pungent and mild/sweet can sometimes overshadow distinctions involving color. For example, you may hear the term "sweet onions" being used to differentiate these varieties from either yellow or red or white onions.

Taste differences in onions may sometimes be related to day length. In the United States, for example, "long-day" onions commonly grown in Washington, Illinois, and New York often include well-known (and much loved) sweet varieties. "Intermediate-day" onions grown in Northern California and Colorado also include many sweet varieties. "Short-day" onions more common to southern California, southern Texas, and southern Georgia tend to have fewer representatives in the sweetness category, but there are also plenty of exceptions. For example, the pungency of onions is not only related to day length but also to many other factors including the mildness of the climate and the mineral content of the soil. In some areas with heavy annual rainfall, for example, sulfur can be leached out of the soil in amounts conducive to the creation of sweet onions. One famous example here are Vidalia onions grown in the southern half of Georgia.

You may also hear onions being referred to as "early bulb" or "late bulb." Like this terminology suggests, the varieties involved differ in their speed of bulb formation.

Onions varieties can differ in their perishability, and this perishability is not always predictable based on color, taste, or other easily-detected differences. For example, we have come across research studies on one variety of red onions called "Breme" onions that are only grown on a 25-acre plot of land in northwestern Italy and that are only distributed locally, partially due to their delicate nature. Of course, most of the onions that you will find in the supermarket are not highly perishable in this same way and do not need to be used right away unless they are cut open. For cut, chopped, and diced onions, we always recommend refrigeration in a covered container and use the next day, or two days later at the most.

As you can see from all of the examples above, geography, climate, and timing can make for important differences in the life of an onion, and these types of impacts may be particularly true for sweet onions. It is perhaps for this reason that some sweet onions are very closely linked to a very limited season of harvest. Maui Sweet Onions are known for their peak season between April and June, Vidalia onions for their peak season between April and late August, and Walla Walla Sweets for their peak season between mid-June and mid-August.

Specific varieties of red onions that you might find at a farmer's market or in a supermarket include Redwing, Red River, Red Zeppelin, Red Creole, Southern Belle Red, Red Grano, Red Granex, and California Early Red. Yellow varieties include Yellow Sweet Spanish, Fiesta, Stockton Yellow Globe, Highlander, Copra, and Texas Legend. White varieties include Sterling, Texas Early White, and Ringmaster White Spanish.

HISTORY

As mentioned earlier in the Description section, onions are a remarkable food in terms of their worldwide geography, and this feature of onions is quickly visible in their history. Most researchers point to Central Asia as the original birthplace of onions; included in this area would be the present-day countries of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan, and Afghanistan. Along with the countries of Northern Africa—including Algeria, Morocco, and Egypt—these Central Asian countries still serve as one of the largest onion-growing regions in the world. However, joining these countries as major onion producers have been countries like Myanmar and South Korea in southeast Asia, as well as Brazil in South America and the United States in North America. In fact, today it has become somewhat difficult to find a widely adopted cuisine that does not feature onions in some form or other.

Within the United States, California is by far the largest onion-producing state, followed by Washington, Oregon, Texas, and Georgia. At the same time, however, onions are now grown commercially in over 15 different states. And while far more onions are consumed per capita in the countries of Libya, Albania, Tajikistan, Uzbekistan, and Algeria than in the United States, the U.S. still ranks in the world's Top 10 onion-consuming countries, and in some surveys, onions rank as the third most consumed vegetables in terms of volume, following tomatoes and potatoes. (Here it would be important to note, however, that consumption of these vegetables does not necessarily mean that they have been consumed in their fresh, whole food form.) Research estimate suggest that in the U.S., the average per capita intake of onions in all forms is about 25 pounds per year, or roughly ½ pound per week.

On a worldwide basis, the top onion-producing countries in the world include China, India, the United States, Iran, Turkey, Egypt, Pakistan, Bangladesh, Indonesia, Myanmar, Russia, and Brazil.

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 at the very most 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 AND COOKING

Cut onions into 1/4-inch slices to cook them evenly and quickly.

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.) Recent research has shown that LF gas is not produced through activity of onion's alliinase enzyme, but rather through the activity of a special enzyme named lachrymatory-factor synthase. Interestingly, even though lachrymatory-factor synthase is the enzyme responsible for production of LF gas, the alliinase enzyme must still be present in order for LF gas production to occur.

Of course, no sooner had this new tear-producing enzyme been discovered than researchers began looking for ways to switch off the gene that served as the blueprint for this enzyme. However, "silencing" the gene without compromising the health benefits of the onion turned out to be a difficult task. Even though researchers in Japan succeeded in shutting down the gene and preventing production of lachrymatory-factor enzyme (thereby paving the way for a genetically engineered onion that would not produce LF gas and cause tearing), they also determined that the shutdown of the gene caused significant (and mostly unwanted) changes in the overall mixture of sulfur-containing molecules in onion.

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.

The Nutrient-Rich Way of Cooking Onions

Although onions are most often used as a seasoning, we want to share with you how to enjoy them as a healthy side dish. For great flavor and nutrition we recommend Healthy Sautéeing sliced onions.

Healthy SautéQuick Steaming—similar to Quick Boiling and Quick Steaming, our other recommended cooking methods—follows three basic cooking guidelines that are generally associated in food science research with improved nutrient retention. These three guidelines are: (1) minimal necessary heat exposure; (2) minimal necessary cooking duration; (3) minimal necessary food surface contact with cooking liquid.

Heat 2 TBS vegetable or chicken broth over medium heat in a stainless steel skillet. When broth begins to steam, add onions and cover for 3 minutes. The onions will release a small amount of liquid. Uncover, add another 2 TBS broth, and continue to stir for 4 minutes, leaving the lid off. Toss with our Mediterranean Dressing and top with your favorite optional ingredients.

HOW TO ENJOY

A Few Quick Serving Ideas

• 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.

NUTRITIONAL PROFILE

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. A wide variety of allyl sulfides are found in onion, including the four major diallyl sulfides: DMS (diallyl monosulfide), DDS (diallyl disulfide), DTS (diallyl trisulfide), and DTTS (diallyl tetrasulfide). Also present are a wide variety of sulfoxides, including (+) S-methyl-L-cysteine sulfoxide (MCSO), (+)-S-(1-propenyl)-L-cysteine sulfoxide (PRENCSO), S-methyl-l-cysteine sulfoxide, S-propyl-l-cysteine sulfoxide, and S-propenyl-l-cysteine sulfoxide.

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.

Sources :

http://www.whfoods.com/genpage.php?tname=foodspice&dbid=45

https://thesecretyumiverse.wonderhowto.com/how-to/9-ways-cut-onion-without-shedding-tears-0147230/