Onions are generally classified by color.
Yellow: These full-flavored cultivars make up 87 percent of the U.S. crop of full-size onions. Cooking brings out their natural nutty sweetness. Yellow onions give French onion soup its tang.
White: A traditional Mexican favorite, these mild onions account for 5 percent of the national crop. They're naturally sweet and preferred for salads or white sauces. Their cell structure is more compact and holds less water; hence, these onions do not keep as long in storage.
Red/purple: Gaining popularity in restaurants, these represent about 8 percent of the total crop. Treasured for their bright color and full flavor, they're often eaten raw, but are great grilled, charbroiled or roasted.
Green: Also called scallions, these are immature onions, picked when stems are still green and the bulbs are small. Some bunching varieties are grown specifically for green onions. Available all year, they're usually used raw or stir-fried.
Shallots: An onion cousin and chef's favorite, these small pointy bulbs are milder than most onions, yet offer more antioxidants.
Coping mechanisms for onions
No more tears: When pierced, onions release sulfur compounds that can irritate eyes and cause tears. Most of those compounds are concentrated in the root end of the bulb.
To cut down on tears while cutting onions, try this tip: Chill the onion at least 30 minutes. Use a very sharp knife.
No onion breath: To counter bad breath from those same sulfur compounds, try munching a piece of parsley. It neutralizes the scent.
Nutrition: One cup of raw, chopped onions contains 64 calories. Onions are high in vitamin C and B6, and fiber and manganese. They add a lot of flavor with no fat, cholesterol or sodium.
Their antioxidant value varies greatly. The more pungent the onion, the better it is for you. Yellow onions have 11 times the amount of flavonoids as white onions. Shallots have six times the disease-fighting phenols as Vidalias. So far, research shows that mild-tasting cultivars (such as Vidalia) show little cancer-fighting ability.
Selection: Dry-bulb onions should feel firm and have little or no scent. Avoid onions with cuts, bruises, blemishes or soft spots.
Storage: Onions must be kept dry. In the right conditions, they'll keep for weeks. Whole, unpeeled bulb onions prefer a cool, dark place with plenty of air circulation. Don't store them in a plastic bag.
Whole sweet onions (especially spring onions with higher water content) can be stored in the refrigerator, but put them in the crisper drawer with a low humidity setting. Green onions should be refrigerated. A cut onion can keep seven days, refrigerated and stored in a sealed container.
Onions can be chopped (or sliced into rings) and frozen for later use.
Distributed by Scripps Howard News Service.