Citrus fruits originated thousands of years ago in southeast Asia, then expanded naturally through other Asian countries until they reached the Mediterranean basin, where the climate was favorable for the seeds, spread by migratory birds, to grow.

Their cultivation began very early in their countries of origin, probably more than 3,000 years ago. It was not until the Middle Ages that the travelers of the time brought them back from their distant journeys and introduced their cultivation to the countries of the Mediterranean basin.

Until the 16th century, the crews of on ships undertaking long-distance voyages were decimated by scurvy, until an English seafarer, Sir Richard Hawkins, showed that lemons were effective protection from this terrible and highly fatal disease. Little by little, it became customary to carry citrus on long sea voyages. It was not until the early 20th century that vitamin C, essential for life, was actually identified and isolated.

Citrus crossed the Atlantic as part of the Conquistadors' rations. They gradually gained a foothold there. Large-scale growing did not begin until the 18th century and it boomed in the 19th.

Once rare outside the producing countries and long considered to be exotic, citrus fruits spread to every country in the world in the 20th century with the development of international freight transport, and have now become commonplace. 

Whichever type it is, a citrus fruit should always be firm and without any traces of mold.

Many are treated to prevent mold growth.

If the zest is going to be used, untreated citrus is preferable by far. 

All citrus fruits are sold whole.

Their flesh, except for that of the kumquat, is made into different juices (natural, concentrated, frozen) and their rinds dehydrated to make powder. You can also find them in frozen or dried slices.

All citrus fruits can be candied. 

Citrus fruits should be stored at ambient temperature in a cool and dry place, but also in the refrigerator or cool room at 4ºC.

All citrus fruits are high in vitamin C, which is their great nutritional feature. They contain some carbohydrate, but no protein or fat.

They also contain antioxidants, minerals, and B vitamins.