One of the pure treasures of winter is a big, juicy orange.

Years ago, when seasonal food wasn’t always available everywhere and anytime, winter meant citrus.

Citrus, well known for its vitamin C content, is at its prime during the cold and flu season. That makes it an even more important food to include in a diet. Fresh citrus builds a body’s immunities – which, in turn, helps ward off colds – and also is a good source of fiber.

Here are a few varieties of oranges to enjoy while they are at their juiciest:

Satsumas

These oranges are part of the mandarin family, which also includes tangerines and clementines. Satsumas are one of the sweeter citrus varieties, with a meltingly tender texture. Their moderately thick skin peels off readily and, with easy-to-separate segments, they make convenient and healthful snacks.

Because they share a similar size and appearance, satsumas often are confused with tangerines and clementines. The main difference is satsumas feature thin membranes filled to capacity with liquid, which means less pulp and more of the prized juice.

Look for satsumas with firm, tight peels (avoid those with hollow-feeling or dented spots); heavier ones are generally juicier. Store at room temperature or in the refrigerator. While refrigeration might prolong storage, it also can dry them out. Fresh satsumas are most enjoyable so use within four or five days.

Clementines

We can thank Spain for the country’s most exquisite export – the fragrant, brightly colored mandarin oranges known as clementines. The fruits were named after Father Clément, the priest who began cultivating them in Algeria at the start of the 20th century.

Clementines have an utterly seductive flavor that is at once intensely citrusy and supremely sweet. The flavor is the result of making a hybrid between the mandarin orange and the bitter Seville.

But the appeal goes further. Like tangerines, to which they are related, clementines are very easy with which to work. Their skin is loose and easy to peel, and the silky flesh inside is virtually seedless (although accidental cross-pollination with seeded fruits can produce the occasional clementine with seeds).

There’s a nutritional payoff, too: An average clementine packs up to half of the recommended dietary allowance for vitamin C and is also a good source of fiber.

Most clementines that are sold during the peak season are packed in charming wooden or cardboard crates with exotic labels and bright- orange netting over the top. Since they generally come packaged this way, it’s not possible to pick individual pieces of fruit. But for the most part, a bag of fruit in season will be ripe and ready to eat.

Kumquats

Tiny and oval-shaped, the kumquat is about the size of a large cherry. Choose firm kumquats that are bright orange in color; avoid those with a greenish tint. Kumquats generally keep at room temperature for up to three days; they can last up to two weeks in the fridge.

For those unfamiliar with the fruit, it might seem odd to eat the entire thing – skin and all – though some will want to pass on the seeds. Kumquats often are found in preserves or fruit salads. They make a nice addition to chutneys or marinades for beef, pork or chicken. Kumquats are also available canned.

Blood oranges

Because blood orange trees can produce flowers, fruit and foliage simultaneously, these succulent fruits have long been associated with fertility. Although some blood oranges are grown in California, most come from Mediterranean countries. They are considered to be among the finer dessert oranges.

Blood oranges feature a thin, red-blushed orange skin, with flesh that ranges in color from pink to brilliant red and burgundy. Taste-wise, they are tart-sweet and slightly berry- like. Choose those that are firm to the touch and heavy for their size. Although bits of green and rough, brownish areas on the skin have no effect on flavor or quality, avoid any fruits with mold or spongy spots. Note: One pound equals about three medium oranges and 1 cup of juice.

To keep these ruby gems fresh longer, choose refrigeration over the fruit bowl. They’ll last only a couple of days at room temperature but up to two weeks in the fridge.

Blood oranges are best eaten fresh out of hand but are delicious cut into salads or turned into salsas or marmalades. Recipes might call for sectioning the fruit. To do so, peel the orange, cut between the white membranes to expose the flesh and remove the sections.