Its about most universal food. The United Nations Organization estimates that of the approximately 200 countries in the world 175 produce onion, twice as many wheat producers. It is not surprising, therefore, that it is present in the vast majority of gastronomic traditions, and for millennia.
Already on some clay tablets originating in Mesopotamia, which contain the oldest known text on cooking (dated approximately 1750 BC, at the time of Hammurabi), there is talk of onions, leeks, garlic and shallots, and their use is distinguished for different preparations.
Nor today, almost 4000 years later, is it difficult to differentiate these species from the alliaceae family (which has 500 species, 20 of them important as food) but it is not so easy to distinguish the different types of onion, which correspond to the species Allium cepa, and know how to take advantage of all its qualities.
Not counting easily distinguishable varieties such as chives, calçots or pearl onions, in Spain we find four main types: yellow, white, red and Vidalia type or sweet. These are their differences and their most important applications in the kitchen:
Yellow onion: the quintessential onion
The conventional onion, which we all have at home, is the one that, traditionally, grew during the summer and was harvested already ripe in the autumn. That is why, although it is sold all year round, it is at this time when they taste sweeter.
It is rich in sulfur compounds, drier and easier to store in a cool and dry place, without the need for refrigeration, for several months.
Although it is acceptable raw, it is the onion par excellence for cooking. Depending on age, it itches more or less, but it always becomes softer when warming up. It is the ideal variety to prepare the base of any dish and also to caramelize.
White onion: the friend of your salads
These onions were the spring ones, as they were planted in the form of shoots in late autumn and harvested before they were fully ripe, in the following spring and early summer. Today they are found all year round and their flavor does not differ too much between seasons. However, they are conserved worse. They can also be stored in a cool and dry place, but they hold less than conventional onions.
This type of onion it is ideal to consume raw, because its flavor is softer and its texture is more crunchy than that of the yellow variety. Thinly sliced, it is the ideal onion to add to a salad, but it is also great when you need to cook quickly, such as a pizza -[la clásica fugazzeta](https://www.directoalpaladar.com/recetas-de-panes/receta-de-pizza-de-onion is prepared with this type of onion) – or for dishes where we want a milder and sweeter flavor, such as case of onion soup. It is also a variety especially popular in Latin America.
Red onion: a note of color
The red onion is similar to the white one, but it is pigmented by water soluble anthocyanins, which gives it its characteristic color. This, in any case, is only present in the superficial layers of each leaf scale and when cooked its color is diluted and turns off.
In terms of flavor and conservation they are similar to white onions, although slightly stronger and spicier. They are found all year round, but in summer and early fall they have a milder flavor as their acidity intensifies throughout winter.
It does not make much sense to use this onion for hot preparations, for which we will obtain better results with the yellow variety, but works wonders in salads or to make pickles or macerations, such as ceviche, where its presence is mandatory.
Vidalia onion: the sweetest variety
The Vidalia onion owes its surname to the town of the same name, in the state of georgia (USA). It is actually a spring onion that is grown in low sulfur soils and that, therefore, it has half, or less, the usual amounts of chemical defenses based on compounds of this mineral. This makes her much softer and sweeter. Although, again, it is available all year round, the ideal is to buy them between the end of April and the beginning of September.
Although its flavor is more similar to that of the white onion, its external appearance makes it easily confused with the conventional yellow onion, although it is usually somewhat more flattened. In Spain it is usually marketed with the label of “sweet onion”. It is important not to confuse it with flat onion, very typical in Galicia, which is actually a yellow onion, nothing to do with this variety.
It is a great option for eat raw, as it is the least strong option, and it is also the ideal variety to make onion rings.
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