Vidalia, Walla Walla and Maui are familiar sweet onions. They are useful when you want a mild onion flavor in salads, sandwiches or other dishes where the onion is eaten raw.
An onion can taste sweet because it has less of the sharp, pungent flavor that masks its natural sugars. The name on the label is more useful than color alone when you are choosing a sweet onion.
This guide compares common sweet onions with yellow, red and white onions, and explains how to store them.
Do All Onions Have Sugar?
Onions contain natural sugars, but sugar is only part of how they taste. Their sharpness comes from sulfur-containing compounds, and the balance varies with the variety and growing conditions.
The University of Georgia onion guide describes differences in both sugar content and pungency among varieties. So a sweeter-tasting onion does not, by itself, tell you how much sugar it contains.
Yellow Onions
Yellow onions are the most popular and commonly used variety of onions. They are abundantly available and inexpensive.
These onions have a rich ivory color beneath their thick brown skin. They have a balanced flavor that’s both pungent and sweet.
Yellow onions often have a stronger raw flavor, which is why they are a common choice for cooked dishes. Whether you enjoy them raw depends on the onion and your taste.
However, these onions caramelize beautifully and add more flavor to dishes.
Heat brings out their sweetness. Cooking them also cuts their pungency and allows the rest of their flavors to shine.
Red Onions
Red onions have red-purple skin and pale flesh with colored rings. Their flavor can range from mild to quite sharp, so red skin alone does not guarantee a sweet onion.
They add color and crunch to salads and sandwiches, but they also work well cooked. The National Onion Association recommends red onions for grilling and roasting as well as fresh uses.
White Onions
White onions have white skin and flesh. They can have a sharp flavor, so do not assume they will be milder than a red or yellow onion.
They are often used in salsa and other fresh dishes, and they also become sweet and golden when sautéed. Choose them for the flavor you want in the recipe rather than a fixed sweetness ranking.
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Sweet Onions
Sweet onions are sold for their mild flavor, which makes them useful in salads, sandwiches and burgers. Vidalia, Maui and Walla Walla are familiar examples. Their size and shape vary, so check the label rather than relying only on a flat shape or light skin.
Many sweet onions have more water and thinner skins than storage onions. That helps explain why they do not keep as long; it is not simply a matter of containing more sugar.
For longer storage, the National Onion Association recommends wrapping whole sweet onions in paper towels and refrigerating them. Keep them dry. You do not need to peel a whole onion just to put it in the refrigerator.
Once you have peeled or cut an onion, keep it refrigerated. Store cut pieces in a closed container, and keep the refrigerator at 40°F (4°C) or below.
Shallots
Shallots are small members of the onion family with a sweet, delicate flavor and a hint of garlic. Their sharpness can vary, so they do not belong at a fixed point above red or yellow onions on a sweetness scale.
Use them when you want their particular flavor in a dressing, sauce or cooked dish.
Why Are Vidalia Onions Sweet?
Vidalia onions are grown in a designated region of South Georgia. The varieties and growing conditions help produce their mild flavor.
The University of Georgia explains that soils in the growing area are naturally low in sulfur, and sulfur management affects pungency. A milder flavor allows the onion’s natural sweetness to stand out, although the flavor and sugar content can still vary.
What Onions Are Sweeter – Red Or Yellow?
There is no reliable sweetness ranking based on red or yellow skin alone. Variety, growing conditions and how you prepare the onion all affect the flavor.
If you want a mild onion to eat raw, choose one labelled sweet. Yellow onions are a versatile choice for cooking, while red onions can be used raw, grilled or roasted. If you compare nutrition figures, make sure they refer to the same serving size and the same form of onion, such as raw or cooked.
Related: What Can You Use Instead of Vidalia Onions?
Which Onions Are Sweeter When Cooked?
Onions become softer and can taste sweeter as they cook. Yellow onions are a common choice for a deeply browned onion flavor, but red, white and sweet onions can also be cooked.
For deeper browning, allow time and control the heat instead of expecting the color to change immediately. Oregon State University Extension recommends longer cooking at lower heat for golden-brown onions. Stir as needed and reduce the heat if they begin to burn.
The result depends on the onion, how thickly it is sliced and how it is cooked. You do not need to add sugar simply to make onions brown.
